The authors thank Davy Opdenacker for technical assistance and photography. We greatly thank Dr. Annick Bleys for helpful suggestions to improve the manuscript. This work was financed by the Interuniversity Attraction Poles Programme IUAP P7/29 'MARS' from the Belgian Federal Science Policy Office, by the FWO grant G027313N and by the Agency for Innovation by Science and Technology, IWT (IR).

1. Arabidopsis LRIS Protocol
Note: The text refers to &#34;small&#34; or &#34;large&#34; scale experiments. Small scale experiments, such as marker line analysis and histological staining6, 14, require only a few samples. Large scale experiments, such as quantitative real-time qRT-PCR, micro-arrays9-11 or RNA sequencing, require a larger amount of samples. As such, an amount of ~1000 seedlings per sample was used by Vanneste et al.11 to perform microarray experiment after root segment dissection.
DAY 1
<ol>
	<li>Sterilization of Arabidopsis Seeds 
	Note: Select one of the following procedures for seed sterilization. Any of them is suitable for the next steps of the protocol. Gas sterilization (1.1.2) presents two main advantages over liquid sterilization (1.1.1): it takes less time when handling a large number of seeds, since no pipetting has to occur for the individual samples; and the sterilized seeds can be stored for a longer period. However, it requires a desiccator and careful handling.
	<ol>
		<li>Liquid sterilization
		<ol>
			<li>Pour the desired number of seeds in micro-centrifuge tubes. Use up to 20 mg (~800 seeds) in a 1.5&#160;ml&#160;tube or 40 mg (~1600 seeds) in a 2 ml&#160;micro-centrifuge tubes.</li>
			<li>Add 1 ml of 70% ethanol. Invert or gently shake for 2 min.</li>
			<li>Replace the 70% ethanol with 1 ml sterilization solution for 15 min. (Prepare fresh sterilization solution: 3.85 ml sodium hypochlorite (NaOCl) stock (12%) (CAUTION: Use fume hood), 5 &#181;l&#160;Tween 20, up to 10 ml with water. Invert the tubes several times to make sure that all seeds come in contact with the solution.</li>
			<li>In a laminar air flow cabinet, replace the sterilization solution with 1 ml sterile distilled water and rinse the seeds 5 times for 5 min by repeatedly replacing with 1 ml of fresh sterile distilled water.</li>
		</ol>
		</li>
		<li>Gas Sterilization
		<ol>
			<li>Pour the desired number of seeds in a 2 ml micro-centrifuge tube. Use individual tubes when working with several independent lines, and arrange them opened in a plastic micro-centrifuge tubes box or holder. If the number of seeds in one tube exceeds 500 (12.5 mg), subdivide the seeds in the appropriate number of tubes to ensure successful sterilization.&#160;Make sure the caps of neighboring tubes do not cover each other. Fit together the lid of the box on the bottom, as it needs to be in the desiccator as well for sterilization.</li>
			<li>Place the box in the bowl of a desiccator, along with a glass beaker (CAUTION: Use fume hood).</li>
			<li>Fill the beaker with 100 ml of 12% NaOCl (CAUTION: Use fume hood). Put the lid on the desiccator, but leave a small aperture where the beaker is placed.</li>
			<li>Add 3 ml of 37% hydrochloric acid (fuming) (CAUTION: Use fume hood) to the beaker through the small aperture and quickly close the desiccator. The solution will bubble for some time due to Cl2-gas formation. Leave the system closed O/N (or at least 8 hr).</li>
			<li>Remove the lid of the desiccator. Take out the box and cover it with the lid to avoid contamination during transport.</li>
			<li>Put the box in a laminar air flow cabinet, remove the lid and leave the seeds for about 1 hr at RT&#160;to allow gas release. 
			Note: Seeds can be safely stored dry in closed micro-centrifuge tubes for up to 2 weeks at 4 &#176;C.&#160;&#160;&#160;</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Lateral Root Induction in Arabidopsis
	<ol>
		<li>Lateral Root Inhibition (NPA Treatment)
		<ol>
			<li>Prepare growth medium for in vitro growth. The medium contains half strength Murashige and Skoog salt mixture15, 0.1 g/L myo-inositol, 10 g/L sucrose, and is buffered with 0.5 g/L 2-(N-morpholino)ethanesulfonic acid (MES).</li>
			<li>Adjust the pH to 5.7 with 1 M KOH. Add 8 g/L of plant tissue agar and autoclave the medium for 20 min at 121 &#176;C.</li>
			<li>Prepare a 25 mM stock solution of NPA in dimethylsulfoxide (DMSO) (CAUTION: Use gloves). In a laminar air flow cabinet, cool the autoclaved medium down to approximately 65 &#176;C (which is the temperature at which the bottle can be held by hand), and add 25 mM NPA stock solution to obtain a final concentration of 10 &#181;M NPA.</li>
			<li>Homogenize upon addition by gently shaking the bottle for 10 sec. Pour 50 ml of medium per square petri dish (12 cm x 12 cm). 
			Note: In case of large scale experiment, apply a nylon mesh (20 &#181;m) to ensure easy transfer. Prepare a mesh (9 cm x 9 cm) for autoclaving (Figure 1A). When autoclaved, apply the mesh to the growth medium using sterile tweezers (Figure 1B). Gently push the mesh to the growth medium using a sterilized&#160;drigalsky to make sure it is in good contact with the growth medium (Figure 1B) (CAUTION: Work in sterile conditions).&#160;</li>
			<li>Sow the seeds on the NPA-plates. 
			Note: In case a large scale experiment is planned, sow 2 dense and well-aligned rows of 50 seeds to facilitate the sampling (see 1.2.2.3).
			<ol>
				<li>In case of liquid sterilization, sow the seeds on NPA-plates using a 200 &#181;l pipet. Cut off 3 - 4 mm of the end of the pipetting&#160;tips in sterile conditions (or before sterilization of the tips) in order to be able to pipet the seeds. Pipet up and down a couple of times to re-suspend the seeds, then pipet approximately 150 &#181;l sterile water with 10 - 20 seeds and wait till the seeds sediment at the bottom of the tip. (CAUTION: Work in sterile conditions) 
				Note: When touching the agar or the mesh gently with the tip, a drop of water with a seed will be released from it (Figure 1C).</li>
				<li>In case of gas sterilization, sow the seeds using autoclaved toothpicks.Pinch the toothpick into the agar before taking the seeds to ensure a sticky surface. Pick up the seeds one by one using the toothpick and distribute the seeds on the plates (Figure 1D). Alternatively, add sterile water to the seeds, and sow as described in 1.2.1.5.1 (CAUTION: Work in sterile conditions).</li>
			</ol>
			</li>
			<li>Seal the plates with breathable adhesive tape and store them plates at 4 &#176;C in the dark for at least 2 days and maximum one week. This is needed for stratification and ensures synchronized and more efficient germination. 
			Note: Alternatively, seeds can be stratified before sowing, immersed in distilled water in micro-centrifuge tubes, which requires less refrigerator space. In this case, store the tubes for at least one week at 4 &#176;C, and move the plates to the growth cabinet immediately after sowing (see 1.2.1.7). 
			DAY 3</li>
			<li>Move the plates to the growth cabinet (continuous light (110 &#181;E m-2 s-1), 21 &#176;C) for 5 days (2 days of germination and 3 days of growth) in a nearly vertical position (80 to 90 &#176;) to ensure root growth on, and not in the medium. 
			DAY 8&#160;</li>
		</ol>
		</li>
		<li>Lateral Root Induction (NAA Treatment)
		<ol>
			<li>Prepare the same growth medium as described in 1.2.1.1 and 1.2.1.2. Prepare a 50 mM stock solution of NAA in DMSO (CAUTION: Use gloves). Cool the autoclaved medium down to 65 &#176;C and add NAA solution to the medium to obtain a final concentration of 10 &#181;M NAA (CAUTION: Work in sterile conditions).
			<ol>
				<li>Homogenize upon addition by gently shaking the bottle for 10 sec. Pour 50 ml of medium per square petri dish (12 cm x 12 cm).</li>
			</ol>
			</li>
			<li>Transfer the seedlings from the plates containing growth medium supplemented with 10 &#181;M NPA to those supplemented with 10 &#181;M NAA.
			<ol>
				<li>Hook the arms of curved tweezers under the cotyledons of the seedling and gently remove it from the plate. Only transfer seedlings of which the roots have grown entirely in contact with the NPA-growth medium and preferably downwards.</li>
				<li>Skim the root over the NAA-containing growth medium surface over a small distance. Make sure that the plant roots are in good contact with the growth medium. If needed, press the root gently to the growth medium surface with the tweezers. 
				Note: In case of a large-scale experiment, remove all seedlings that are not in contact with the mesh and transfer by lifting the mesh at the two upper corners with tweezers. Make sure the mesh is in good contact with the NAA-containing medium by skimming the mesh over the agar surface over a small distance (Figure 1E).&#160;</li>
			</ol>
			</li>
			<li>Seal the new plates with breathable tape and place them in the growth cabinet (continuous light (110 &#181;E m-2 s-1), 21 &#176;C) in a vertical position for the desired time after induction until sampling. 
			Note: In case of a large-scale experiment, use a scalpel to cut the root segments all at once directly on the mesh and sample them by gently scraping the surface of the mesh.&#160;&#160;</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
2. LRIS Maize Protocol
<ol>
	<li>Stratification of Maize Kernels
	<ol>
		<li>Incubate the maize kernels at 4 &#176;C in the dark for at least 1 week. 
		Note: This protocol has been developed using the B73 maize inbred line.</li>
	</ol>
	</li>
	<li>Sterilization of Maize Kernels 
	DAY 1 
	Note: Although maize seedlings do not have to be grown in sterile conditions, it is recommended to sterilize the maize kernels and work with sterile material to prevent fungal growth in the paper roll system.
	<ol>
		<li>Put the necessary number of maize kernels in a sterilized glass beaker.</li>
		<li>Add 100 ml of sterilization solution (6% NaOCl in water) (CAUTION: Use fume hood).</li>
		<li>Add a magnetic stir bar and place the beaker on a magnetic stirrer at low stirring speed (approximately 250 rpm) at RT&#160;for 5 min.</li>
		<li>Rinse five times for 5 min by replacing the solution with 100 ml of fresh sterile water.</li>
	</ol>
	</li>
	<li>&#160;Sowing Maize Kernels
	<ol>
		<li>Put on gloves to reduce the risk of contamination, and take a roll of paper towels.</li>
		<li>Tear off two stretches of hand towel paper with a total length of two sheets (approximately 92 cm x 24 cm) and place them on top of each other on a clean surface (Figure 2A).</li>
		<li>Fold the sheets double over the length (approximately 92 cm x 12 cm) (Figure 2A).</li>
		<li>Use tweezers to distribute 10 kernels at approximately 2 cm from the top over the entire length of the paper, while keeping an interspace of 8 cm between each kernel and 8 cm free at both ends (Figure 2B). Make sure the radicle of the kernel is facing down and toward the paper (Figure 2B).</li>
		<li>Gently roll the paper over the length, while keeping the seeds in place (Figure 2B). To facilitate the rolling, it is optional to first spray the paper with sterile water.</li>
		<li>Put the paper rolls in sterilized glass tubes of approximately 6 cm diameter and 14 cm height (e.g., 250 ml centrifuge tubes) and place them in a rack (Figure 2C).</li>
	</ol>
	</li>
	<li>Lateral Root Induction in Maize
	<ol>
		<li>Prepare a 50 mM NPA stock solution (dissolved in DMSO) (CAUTION: Use gloves).</li>
		<li>For each tube, make a 50 &#181;M NPA solution by adding 125 &#181;l from the 50 mM NPA stock solution to 125 ml sterile water in a sterilized glass beaker.</li>
		<li>Mix well and pour 125 ml of the 50 &#181;M NPA solution over the paper roll in the tube. The paper roll will absorb the solution and become completely soaked. 
		Note: When using paper rolls and tubes with other dimensions, adjust the volume accordingly. The liquid should reach halfway the tube to ensure sufficient uptake.</li>
		<li>Place the paper roll system in a growth cabinet for three days (27 &#176;C, continuous light, 70% relative humidity). Make sure that the paper rolls remain soaked by adding extra 50 &#181;M NPA solution, since the solution evaporates over time (Figure 2D). 
		DAY 4</li>
		<li>Prepare a 50 mM NAA stock solution (dissolved in DMSO) (CAUTION: Use gloves).</li>
		<li>For each tube, prepare a 50 &#181;M NAA solution by adding 125 &#181;l from the 50 mM NAA stock to 125 ml sterile water in a sterilized glass beaker.</li>
		<li>Gently squeeze out most of the remaining NPA solution from the paper rolls and place them in sterile water for 5 min to wash it out (CAUTION: Use gloves). Gently squeeze out most of the water from the paper rolls. Repeat this washing step three times.</li>
		<li>Mix well and pour the 50 &#181;M NAA solution over the paper rolls in the tubes. Make sure they are completely soaked.</li>
		<li>Place the paper roll system in the growth cabinet (27 &#176;C, continuous light, 70% relative humidity) for the desired duration after induction.</li>
	</ol>
	</li>
	<li>Lateral Root Induction in Adventitious Crown Roots of Maize 
	Note: The LRIS as described above induces lateral roots in the primary root. However, in maize and other monocotyledons, the primary root and the embryonic seminal roots, together with their lateral roots, are mainly important during seedling development. At a later stage in plant growth, the post-embryonic adventitious roots arise on the stem and also develop lateral roots to form a new root system16. The LRIS can also be used to induce lateral roots on these post-embryonic adventitious crown roots by following some minor adjustments to the LRIS on the embryonic primary root.
	<ol>
		<li>To make the paper rolls, create a sandwich of papers with respectively two layers of hand towel paper on the outer side, and two layers of germination paper within. Place the sterilized kernels (see steps 2.1 to 2.2) in between the two sheets of germination paper. Germination paper, compared to hand towel paper, will be less prone to be penetrated by root hairs and lateral roots, which will make the opening of the paper rolls easier later on. On the other hand, the two external layers of hand towel paper will facilitate absorption of the liquid.</li>
		<li>Insert the rolls in 700 ml glass tubes and pour sterile water without NPA over them. Make sure they are completely soaked.</li>
		<li>Germinate the sterilized kernels in the growth cabinet (see step 2.4.9).</li>
		<li>Grow the seedlings till the adventitious crown roots start to emerge (6 days for B73). Make sure the paper rolls are kept wet at all times by adding sterile water when necessary.</li>
		<li>Transfer to a 25 &#181;M NPA solution for 4 days (see steps 2.4.1 to 2.4.4), followed by a similar induction of lateral root initiation by replacing the NPA solution with a 50 &#181;M NAA solution after a washing step (see step 2.4.5 to 2.4.9).</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Van Norman, J. M., Xuan, W., Beeckman, T., Benfey, P. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=To+branch+or+not+to+branch:+the+role+of+pre-patterning+in+lateral+root+formation.">To branch or not to branch: the role of pre-patterning in lateral root formation.</a> Development. 140, 4301-4310 (2013).</li><li>Dolan, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+organisation+of+the+Arabidopsis+thaliana+root.">Cellular organisation of the Arabidopsis thaliana root.</a> Development. 119, 71-84 (1993).</li><li>Bell, J. K., McCully, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+histological+study+of+lateral+root+initiation+and+development+in+Zea+mays.">A histological study of lateral root initiation and development in Zea mays.</a> Protoplasma. 70, 179-205 (1970).</li><li>Benkova, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Local,+efflux-dependent+auxin+gradients+as+a+common+module+for+plant+organ+formation.">Local, efflux-dependent auxin gradients as a common module for plant organ formation.</a> Cell. 115, 591-602 (2003).</li><li>Beeckman, T., Burssens, S., Inz&#233;, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+peri-cell-cycle+in+Arabidopsis.">The peri-cell-cycle in Arabidopsis.</a> J. Exp. Bot. 52, 403-411 (2001).</li><li>Himanen, K., Boucheron, E., Vanneste, S., de Almeida Engler, J., Inz&#233;, D., Beeckman, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxin-mediated+cell+cycle+activation+during+early+lateral+root+initiation.">Auxin-mediated cell cycle activation during early lateral root initiation.</a> Plant Cell. 14, 2339-2351 (2002).</li><li>Jansen, L., Parizot, B., Beeckman, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inducible+system+for+lateral+roots+in+Arabidopsis+thaliana+and+maize.">Inducible system for lateral roots in Arabidopsis thaliana and maize.</a> Methods Mol Biol. 959, 149-158 (2013).</li><li>Casimiro, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxin+transport+promotes+Arabidopsis+lateral+root+initiation.">Auxin transport promotes Arabidopsis lateral root initiation.</a> Plant Cell. 13, 843-852 (2001).</li><li>Himanen, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcript+profiling+of+early+lateral+root+initiation.">Transcript profiling of early lateral root initiation.</a> Proc. Natl. Acad. Sci. USA. 101, 5146-5151 (2004).</li><li>De Smet, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Receptor-like+kinase+ACR4+restricts+formative+cell+divisions+in+the+Arabidopsis+root.">Receptor-like kinase ACR4 restricts formative cell divisions in the Arabidopsis root.</a> Science. 322, 594-597 (2008).</li><li>Vanneste, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+cycle+progression+in+the+pericycle+is+not+sufficient+for+SOLITARY+ROOT/IAA14-mediated+lateral+root+initiation+in+Arabidopsis+thaliana.">Cell cycle progression in the pericycle is not sufficient for SOLITARY ROOT/IAA14-mediated lateral root initiation in Arabidopsis thaliana.</a> Plant Cell. 17, 3035-3050 (2005).</li><li>De Rybel, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+role+for+the+root+cap+in+root+branching+revealed+by+the+non-auxin+probe+naxillin.">A role for the root cap in root branching revealed by the non-auxin probe naxillin.</a> Nat. Chem. Biol. 8, 798-805 (2012).</li><li>Jansen, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+transcriptomics+as+a+tool+for+the+identification+of+root+branching+genes+in+maize.">Comparative transcriptomics as a tool for the identification of root branching genes in maize.</a> Plant Biotechnol. J. 11, 1092-1102 (2013).</li><li>Parizot, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diarch+symmetry+of+the+vascular+bundle+in+Arabidopsis+root+encompasses+the+pericycle+and+is+reflected+in+distich+lateral+root+initiation.">Diarch symmetry of the vascular bundle in Arabidopsis root encompasses the pericycle and is reflected in distich lateral root initiation.</a> Plant Physiol. 146, 140-148 (2008).</li><li>Murashige, T., Skoog, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+revised+medium+for+rapid+growth+and+bio+assays+with+tobacco+tissue+cultures.">A revised medium for rapid growth and bio assays with tobacco tissue cultures.</a> Physiol. Plant. 15, 473-497 (1962).</li><li>Bellini, C., Pacurar, D. I., Perrone, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adventitious+roots+and+lateral+roots:+similarities+and+differences.">Adventitious roots and lateral roots: similarities and differences.</a> Annu Rev Plant Biol. 65, 639-666 (2014).</li><li>Grunewald, W., Parizot, B., Inz&#233;, D., Gheysen, G., Beeckman, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developmental+biology+of+roots:+One+common+pathway+for+all+angiosperms?.">Developmental biology of roots: One common pathway for all angiosperms?.</a> Int. J. Plant Dev. Biol. 1, 212-225 (2007).</li><li>Parizot, B., Beeckman, T., Crespi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genomics+of+root+development.">Genomics of root development.</a> Root Genomics and Soil Interactions. , 3-28 (2012).</li><li>Bargmann, B. O., Birnbaum, K. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+activated+cell+sorting+of+plant+protoplasts.">Fluorescence activated cell sorting of plant protoplasts.</a> Journal of visualized experiments : JoVE. , (2010).</li><li>Nakazono, M., Qiu, F., Borsuk, L. A., Schnable, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser-capture+microdissection,+a+tool+for+the+global+analysis+of+gene+expression+in+specific+plant+cell+types:+identification+of+genes+expressed+differentially+in+epidermal+cells+or+vascular+tissues+of+maize.">Laser-capture microdissection, a tool for the global analysis of gene expression in specific plant cell types: identification of genes expressed differentially in epidermal cells or vascular tissues of maize.</a> Plant Cell. 15, 583-596 (2003).</li><li>Ludwig, Y., Hochholdinger, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+microdissection+of+plant+cells.">Laser microdissection of plant cells.</a> Methods Mol Biol. 1080, 249-258 (2014).</li><li>Beeckman, T., Engler, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+easy+technique+for+the+clearing+of+histochemically+stained+plant+tissue.">An easy technique for the clearing of histochemically stained plant tissue.</a> Plant Mol. Biol. Rep. 12, 37-42 (1994).</li><li>Ditengou, F. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+induction+of+lateral+root+initiation+in+Arabidopsis+thaliana.">Mechanical induction of lateral root initiation in Arabidopsis thaliana.</a> Proc. Natl. Acad. Sci. USA. 105, 18818-18823 (2008).</li><li>Lucas, M., Godin, C., Jay-Allemand, C., Laplaze, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxin+fluxes+in+the+root+apex+co-regulate+gravitropism+and+lateral+root+initiation.">Auxin fluxes in the root apex co-regulate gravitropism and lateral root initiation.</a> J. Exp. Bot. 59, 55-66 (2008).</li><li>Wang, S., Taketa, S., Ichii, M., Xu, L., Xia, K., Zhou, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lateral+root+formation+in+rice+(Oryza+Sativa.+L.):+differential+effects+of+indole-3-acetic+acid+and+indole-3-butyric+acid.">Lateral root formation in rice (Oryza Sativa. L.): differential effects of indole-3-acetic acid and indole-3-butyric acid.</a> Plant Growth Regul. 41, 41-47 (2003).</li><li>Martinez-de la Cruz, E., Garcia-Ramirez, E., Vazquez-Ramos, J. M., Reyes de la Cruz, H., Lopez-Bucio, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxins+differentially+regulate+root+system+architecture+and+cell+cycle+protein+levels+in+maize+seedlings.">Auxins differentially regulate root system architecture and cell cycle protein levels in maize seedlings.</a> J Plant Physiol. 176, 147-156 (2015).</li><li>Beyer, E. M., Morgan, P. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+ethylene+on+uptake,+distribution,+and+metabolism+of+indoleacetic+acid-1-14C+and+-2-14C+and+naphthaleneacetic+acid-1-14C.">Effect of ethylene on uptake, distribution, and metabolism of indoleacetic acid-1-14C and -2-14C and naphthaleneacetic acid-1-14C.</a> Plant Physiol. 46, 157-162 (1970).</li><li>Delbarre, A., Muller, P., Imhoff, V., Guern, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+mechanisms+controlling+uptake+and+accumulation+of+2,4-dichlorophenoxy+acetic+acid,+naphthalene-1-acetic+acid,+and+indole-3-acetic+acid+in+suspension-cultured+tobacco+cells.">Comparison of mechanisms controlling uptake and accumulation of 2,4-dichlorophenoxy acetic acid, naphthalene-1-acetic acid, and indole-3-acetic acid in suspension-cultured tobacco cells.</a> Planta. 198, 532-541 (1996).</li><li>Bailey-Serres, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microgenomics:+genome-scale,+cell-specific+monitoring+of+multiple+gene+regulation+tiers.">Microgenomics: genome-scale, cell-specific monitoring of multiple gene regulation tiers.</a> Annu Rev Plant Biol. 64, 293-325 (2013).</li><li>Perez-Torres, C. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phosphate+availability+alters+lateral+root+development+in+Arabidopsis+by+modulating+auxin+sensitivity+via+a+mechanism+involving+the+TIR1+auxin+receptor.">Phosphate availability alters lateral root development in Arabidopsis by modulating auxin sensitivity via a mechanism involving the TIR1 auxin receptor.</a> Plant Cell. 20, 3258-3272 (2008).</li></ol>

The authors have nothing to disclose.

In the Arabidopsis LRIS protocol, it is important to only transfer the seedlings that have grown entirely in contact with the NPA-containing growth medium. This ensures that lateral root initiation is blocked over the entire root length. In order to prevent wounding the plantlets during transfer, the arms of the curved forceps can be hooked under the cotyledons of the seedling. Upon transfer, make sure that the seedling roots are in sufficient contact with the NAA-containing agar medium. This can be achieved by ...

The root system is crucial for plant growth, since it ensures anchorage and uptake of water and nutrients from the soil. Because the expansion of a root system mainly relies on the production of lateral roots, their initiation and formation have been widely studied. Lateral roots are initiated in a specific subset of pericycle cells, called founder cells1. In most dicots, such as Arabidopsis thaliana, these cells are located at the protoxylem poles2, whereas in monocots, such as maize, they are found at the phloem poles3. Founder cells are marked by an increased auxin response4, followed by expression of specific cell cycle genes (e.g.,&#160;CYCLIN B1;1 / CYCB1;1), after which they undergo a first round of asymmetric anticlinal divisions5. After a series of coordinated anticlinal and periclinal divisions, a lateral root primordium is formed that finally will emerge as an autonomous lateral root. The location and timing of lateral root initiation are however not predictable, since these events are neither abundant nor synchronized. This impedes the use of molecular approaches such as transcriptomics to study this process.
To tackle this, a Lateral Root Inducible System (LRIS) has been developed6, 7. In this system, seedlings are first treated with N-1-naphthylphthalamic acid (NPA), which inhibits auxin transport and accumulation, consequently blocking lateral root initiation8. By subsequently transferring the seedling to medium containing the synthetic auxin 1-naphthalene acetic acid (NAA), the entire pericycle layer responds to the elevated auxin levels thereby massively inducing lateral root initiating cell divisions6. As such, this system leads to fast, synchronous and extensive lateral roots initiations, allowing easy collection of root samples enriched for a specific stage of lateral root development. Subsequently, these samples can be used to determine genome-wide expression profiles during lateral root formation. The LRIS has yielded already significant knowledge about lateral root initiation in Arabidopsis and maize9-13, but the need to apply this system to other plant species becomes more apparent as more genomes are sequenced and there is an increasing interest to transfer knowledge to economical important species.
Here, the detailed protocols of the Arabidopsis and maize LRISs are given. Next, an example of the use of the system is provided, by illustrating how transcriptomics data gained from the maize LRIS can be used to identify functional homologs that have a conserved function during lateral root initiation across different plant species. Finally, guidelines to optimize the LRIS for other plant species are proposed.

<table border="0" cellpadding="0" cellspacing="0" width="1258">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">ARABIDOPSIS LRIS</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td style="width:551px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Seeds</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Arabidopsis seeds</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td>Col-0 ecotype</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Gas sterilization of seeds</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">micro-centrifuge tubes 1.5 ml</td>
			<td style="width:228px;">SIGMA-ALDRICH</td>
			<td style="width:119px;">0030 125.215</td>
			<td>Eppendorf microtubes 3810X, PCR clean</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">micro-centrifuge tubes 2 ml</td>
			<td style="width:228px;">SIGMA-ALDRICH</td>
			<td style="width:119px;">0030 120.094</td>
			<td>Eppendorf Safe-Lock microcentrifuge tubes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">hydrochloric acid</td>
			<td style="width:228px;">Merck KGaA</td>
			<td style="width:119px;">1,003,171,000</td>
			<td>37% (fuming) for analysis EMSURE ACS,ISO,Reag. Ph Eu</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">glass desiccator</td>
			<td style="width:228px;">SIGMA-ALDRICH</td>
			<td style="width:119px;"></td>
			<td>Pyrex</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:361px;">glass beaker</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">plastic micro-centrifuge tubes box or holder</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Bleach sterilization of seeds</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">ethanol</td>
			<td style="width:228px;">Chem-Lab nv</td>
			<td style="width:119px;">CL00.0505.1000</td>
			<td>Ethanol, abs. 100% a.r. dilute to 70%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">sodium hypochlorite (NaOCl)</td>
			<td style="width:228px;">Carl Roth</td>
			<td style="width:119px;">9062.3</td>
			<td>12%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Tween 20</td>
			<td style="width:228px;">SIGMA-ALDRICH</td>
			<td style="width:119px;">P1379</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">sterile water</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Growth medium</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Murashige and Skoog salt mixture</td>
			<td style="width:228px;">DUCHEFA Biochemie B.V.</td>
			<td style="width:119px;">M0221-0050</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">myo-inositol</td>
			<td style="width:228px;">SIGMA-ALDRICH</td>
			<td style="width:119px;">I5125-100G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">2-(N-morpholino)ethanesulfonic acid (MES)</td>
			<td style="width:228px;">DUCHEFA Biochemie B.V.</td>
			<td style="width:119px;">M1503.0100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">sucrose</td>
			<td style="width:228px;">VWR, Internation LLC</td>
			<td style="width:119px;">27483.294</td>
			<td>D(+)-Sucrose Ph. Eur.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">KOH</td>
			<td style="width:228px;">Merck KGaA</td>
			<td style="width:119px;">1050211000</td>
			<td>pellets for analysis (max. 0.002% Na) EMSURE ACS,ISO,Reag. Ph Eur</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Plant Tissue Culture Agar</td>
			<td style="width:228px;">LabM Limited</td>
			<td style="width:119px;">MC029</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Lateral root induction chemicals</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">N-1-naphthylphthalamic acid (NPA)</td>
			<td style="width:228px;">DUCHEFA Biochemie B.V.</td>
			<td style="width:119px;">No. N0926.0250</td>
			<td>10 &#181;M (Arabidopsis)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">1-naphthalene acetic acid (NAA)</td>
			<td style="width:228px;">DUCHEFA Biochemie B.V.</td>
			<td style="width:119px;">No. N0903.0050</td>
			<td>10 &#181;M (Arabidopsis)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">dimethylsulfoxide (DMSO)</td>
			<td style="width:228px;">SIGMA-ALDRICH</td>
			<td style="width:119px;">494429-1L</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Making a mesh for transfer</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">nylon mesh</td>
			<td style="width:228px;">Prosep byba</td>
			<td style="width:119px;"></td>
			<td>Synthetic nylon mesh 20 &#181;m</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Sowing and seedling handling</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">square petri dish plates</td>
			<td style="width:228px;">GOSSELIN</td>
			<td style="width:119px;">BP124-05</td>
			<td>12 x 12 cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">50 ml DURAN tubes</td>
			<td style="width:228px;">SIGMA-ALDRICH</td>
			<td style="width:119px;">CLS430304</td>
			<td>Corning&#160;50 mL centrifuge tubes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">drigalski</td>
			<td style="width:228px;">Carl Roth</td>
			<td style="width:119px;">K732.1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">pipette</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">cut pipette tips</td>
			<td style="width:228px;">Daslab</td>
			<td style="width:119px;">162001X</td>
			<td>Universal 200, cut off 5 mm of tip before autoclaving</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">breathable tape&#160;</td>
			<td style="width:228px;">3M Deutschland GmbH</td>
			<td style="width:119px;">cat. no. 1530-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">tweezers</td>
			<td style="width:228px;">Fiers nv/sa</td>
			<td style="width:119px;">K342.1; K344.1</td>
			<td>Dumont tweezers type a nr 5; Dumont tweezers type e nr 7</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Growth conditions</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">growth room</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td>21 &#176;C, continuous light</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Materials</td>
			<td style="width:228px;">Company</td>
			<td style="width:119px;">Catalog</td>
			<td>Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">MAIZE LRIS</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Seeds</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Maize kernels</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td>B-73</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Bleach sterilization of kernels</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:361px;">glass beaker</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">magnetic stirrer&#160;</td>
			<td style="width:228px;">Fiers nv/sa</td>
			<td style="width:119px;">C267.1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">sodium hypochlorite (NaOCl)</td>
			<td style="width:228px;">Carl Roth</td>
			<td style="width:119px;">9062.3</td>
			<td>12%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">sterile water</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Lateral root induction chemicals</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">N-1-naphthylphthalamic acid (NPA)</td>
			<td style="width:228px;">DUCHEFA Biochemie B.V.</td>
			<td style="width:119px;">No. N0926.0250</td>
			<td>50 &#181;M (maize primary root), 25 &#181;M (maize adventitious root)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">1-naphthalene acetic acid (NAA)</td>
			<td style="width:228px;">DUCHEFA Biochemie B.V.</td>
			<td style="width:119px;">No. N0903.0050</td>
			<td>50 &#181;M (maize)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">dimethylsulfoxide (DMSO)</td>
			<td style="width:228px;">SIGMA-ALDRICH</td>
			<td style="width:119px;">494429-1L</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Sowing and seedling handling</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">paper hand towels</td>
			<td style="width:228px;">Kimberly-Clark Professional*</td>
			<td style="width:119px;">6681</td>
			<td>SCOTT Hand Towels - Roll / White; sheet size (24 x 46 cm)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">seed germination paper</td>
			<td style="width:228px;">Anchor Paper Company</td>
			<td style="width:119px;"></td>
			<td>10 X 15 38# seed germination paper</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">tweezers</td>
			<td style="width:228px;">Fiers nv/sa</td>
			<td style="width:119px;">K342.1; K344.1</td>
			<td>Dumont tweezers type a nr 5; Dumont tweezers type e nr 7</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">250 ml (centrifuge) tubes</td>
			<td style="width:228px;">SCHOTT DURAN</td>
			<td style="width:119px;">2160136</td>
			<td>approx. 5.6 cm diameter and 14.7 cm height&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">700 ml tubes</td>
			<td style="width:228px;">DURAN GROUP</td>
			<td style="width:119px;">213994609</td>
			<td>cylinders, round foot tube, D 60&#160; x 250</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">rack</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td>for maize tubes, home made</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">sterile water</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Growth conditions</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">growth cabinet</td>
			<td style="width:228px;"></td>
			<td style="width:119px;"></td>
			<td>27 &#176;C, continuous light, 70% relative humidity</td>
		</tr>
	</tbody>
</table>

lateral root inducible system in arabidopsis and maize

Lateral root development contributes significantly to the root system, and hence is crucial for plant growth. The study of lateral root initiation is however tedious, because it occurs only in a few cells inside the root and in an unpredictable manner. To circumvent this problem, a Lateral Root Inducible System (LRIS) has been developed. By treating seedlings consecutively with an auxin transport inhibitor and a synthetic auxin, highly controlled lateral root initiation occurs synchronously in the primary root, allowing abundant sampling of a desired developmental stage. The LRIS has first been developed for Arabidopsis thaliana, but can be applied to other plants as well. Accordingly, it has been adapted for use in maize (Zea mays). A detailed overview of the different steps of the LRIS in both plants is given. The combination of this system with comparative transcriptomics made it possible to identify functional homologs of Arabidopsis lateral root initiation genes in other species as illustrated here for the CYCLIN B1;1 (CYCB1;1) cell cycle gene in maize. Finally, the principles that need to be taken into account when an LRIS is developed for other plant species are discussed.

Application of the LRIS to Perform Comparative Transcriptomics of the Lateral Root Initiation Process
One application of the LRIS is the comparison and correlation of gene expression profiles during lateral root formation in different species. Comparative transcriptomics approaches create the possibility to pinpoint orthologous genes involved in the lateral root development process in different species. Lateral ...

Watch this Scientific Journal Video about Lateral Root Inducible System in Arabidopsis and Maize at JoVE.com

Lateral Root Inducible System in Arabidopsis and Maize | Biology | Video

Lateral Root Inducible System in Arabidopsis and Maize

The Lateral Root Inducible System (LRIS) allows for synchronous induction of lateral roots and is presented for Arabidopsis thaliana and maize.

Lateral Root Inducible System in Arabidopsis and Maize

Lateral root development contributes significantly to the root system, and hence is crucial for plant growth. The study of lateral root initiation is ...

lateral-root-inducible-system-in-arabidopsis-and-maize

Research

Education

JoVE Journal

JoVE Core

Biology

Plant Biology

Plant Structure, Growth, and Nutrition

SCIENTISTS IN ACTION

13.7K Views.  Ghent. The Lateral Root Inducible System (LRIS) allows for synchronous induction of lateral roots and is presented for Arabidopsis thaliana and maize.

Video: Lateral Root Inducible System in Arabidopsis and Maize

Preparation and Maintenance of Dorsal Root Ganglia Neurons in Compartmented Cultures

Neurons extend axonal processes that are far removed from the cell body to innervate target tissues, where target-derived growth factors are required for neuronal survival and function. Neurotrophins are specifically required to maintain the survival and differentiation of innervating sensory neurons but the question of how these target-derived neurotrophins communicate to the cell body of innervating neurons has been an area of active research for over 30 years. The most commonly accepted model of how neurotrophin signals reach the cell body proposes that signaling endosomes carry this signal retrogradely along the axon. In order to study retrograde transport, a culture system was originally devised by Robert Campenot, in which cell bodies are isolated from their axons. The technique of preparing these compartmented chambers for culturing sensory neurons recapitulates the selective stimulation of neuron terminals that occurs in vivo following release of target-derived neurotrophins. Retrograde signaling events that require long-range microtubule dependent retrograde transport have important implications for the treatment of neurodegenerative disorders.

Here we describe the technique of preparing and maintaining compartmented chambers for culturing sensory neurons of the dorsal root ganglia.

Neurons extend axonal processes that are far removed from the cell body to innervate target tissues, where target-derived growth factors are required for ...

Do-It-Yourself Device for Recovery of Cryopreserved Samples Accidentally Dropped into Cryogenic Storage Tanks

Liquid nitrogen is colorless, odorless, extremely cold (-196 &deg;C) liquid kept under pressure. It is commonly used as a cryogenic fluid for long term storage of biological materials such as blood, cells and tissues 1,2. The cryogenic nature of liquid nitrogen, while ideal for sample preservation, can cause rapid freezing of live tissues on contact - known as 'cryogenic burn'2, which may lead to severe frostbite in persons closely involved in storage and retrieval of samples from Dewars. Additionally, as liquid nitrogen evaporates it reduces the oxygen concentration in the air and might cause asphyxia, especially in confined spaces2.
In laboratories, biological samples are often stored in cryovials or cryoboxes stacked in stainless steel racks within the Dewar tanks1. These storage racks are provided with a long shaft to prevent boxes from slipping out from the racks and into the bottom of Dewars during routine handling. All too often, however, boxes or vials with precious samples slip out and sink to the bottom of liquid nitrogen filled tank. In such cases, samples could be tediously retrieved after transferring the liquid nitrogen into a spare container or discarding it. The boxes and vials can then be relatively safely recovered from emptied Dewar. However, the cryogenic nature of liquid nitrogen and its expansion rate makes sunken sample retrieval hazardous. It is commonly recommended by Safety Offices that sample retrieval be never carried out by a single person. Another alternative is to use commercially available cool grabbers or tongs to pull out the vials3. However, limited visibility within the dark liquid filled Dewars poses a major limitation in their use.
In this article, we describe the construction of a Cryotolerant DIY retrieval device, which makes sample retrieval from Dewar containing cryogenic fluids both safe and easy.

Here we present a low cost, durable cryotolerant device for sample retrieval from Dewar tanks filled with liquid nitrogen. The ease of construction and modular design of the device makes the process of sample retrieval from cryogenic tanks safe and easy.

Liquid nitrogen is colorless, odorless, extremely cold (-196 &deg;C) liquid kept under pressure. It is commonly used as a cryogenic fluid for long term ...

Using Flatbed Scanners to Collect High-resolution Time-lapsed Images of the Arabidopsis Root Gravitropic Response

Research efforts in biology increasingly require use of methodologies that enable high-volume collection of high-resolution data. A challenge laboratories can face is the development and attainment of these methods. Observation of phenotypes in a process of interest is a typical objective of research labs studying gene function and this is often achieved through image capture. A particular process that is amenable to observation using imaging approaches is the corrective growth of a seedling root that has been displaced from alignment with the gravity vector. Imaging platforms used to measure the root gravitropic response can be expensive, relatively low in throughput, and/or labor intensive. These issues have been addressed by developing a high-throughput image capture method using inexpensive, yet high-resolution, flatbed scanners. Using this method, images can be captured every few minutes at 4,800 dpi. The current setup enables collection of 216 individual responses per day. The image data collected is of ample quality for image analysis applications.

This protocol describes a process for rapid collection of images of Arabidopsis seedlings responding to a gravity stimulus using commercially-available flatbed scanners. The method allows for inexpensive, high-volume capture of high-resolution images amenable for downstream analysis algorithms.

Research efforts in biology increasingly require use of methodologies that enable high-volume collection of high-resolution data. A challenge laboratories ...

An Assay for Lateral Line Regeneration in Adult Zebrafish

Due to the clinical importance of hearing and balance disorders in man, model organisms such as the zebrafish have been used to study lateral line development and regeneration. The zebrafish is particularly attractive for such studies because of its rapid development time and its high regenerative capacity. To date, zebrafish studies of lateral line regeneration have mainly utilized fish of the embryonic and larval stages because of the lower number of neuromasts at these stages. This has made quantitative analysis of lateral line regeneration/and or development easier in the earlier developmental stages. Because many zebrafish models of neurological and non-neurological diseases are studied in the adult fish and not in the embryo/larvae, we focused on developing a quantitative lateral line regenerative assay in adult zebrafish so that an assay was available that could be applied to current adult zebrafish disease models. Building on previous studies by Van Trump et al.17&#160;that described procedures for ablation of hair cells in adult Mexican blind cave fish and zebrafish (Danio rerio), our assay was designed to allow quantitative comparison between control and experimental groups. This was accomplished by developing a regenerative neuromast standard curve based on the percent of neuromast reappearance over a 24 hr time period following gentamicin-induced necrosis of hair cells in a defined region of the lateral line. The assay was also designed to allow extension of the analysis to the individual hair cell level when a higher level of resolution is required.

Because many zebrafish models of neurological and non-neurological diseases are studied in the adult fish rather than the embryo/larvae, we developed a quantitative lateral line regenerative assay that can be applied to adult zebrafish disease models. The assay involved resolution at the 1) neuromast and 2) individual hair cell levels.

Due to the clinical importance of hearing and balance disorders in man, model organisms such as the zebrafish have been used to study lateral line ...

Measuring Spatial and Temporal Ca2+ Signals in Arabidopsis Plants

Developmental and environmental cues induce Ca2+ fluctuations in plant cells. Stimulus-specific spatial-temporal Ca2+ patterns are sensed by cellular Ca2+ binding proteins that initiate Ca2+ signaling cascades. However, we still know little about how stimulus specific Ca2+ signals are generated. The specificity of a Ca2+ signal may be attributed to the sophisticated regulation of the activities of Ca2+ channels and/or transporters in response to a given stimulus. To identify these cellular components and understand their functions, it is crucial to use systems that allow a sensitive and robust recording of Ca2+ signals at both the tissue and cellular levels. Genetically encoded Ca2+ indicators that are targeted to different cellular compartments have provided a platform for live cell confocal imaging of cellular Ca2+ signals. Here we describe instructions for the use of two Ca2+ detection systems: aequorin based FAS (film adhesive seedlings) luminescence Ca2+ imaging and case12 based live cell confocal fluorescence Ca2+ imaging. Luminescence imaging using the FAS system provides a simple, robust and sensitive detection of spatial and temporal Ca2+ signals at the tissue level, while live cell confocal imaging using Case12 provides simultaneous detection of cytosolic and nuclear Ca2+ signals at a high resolution.

Measuring Spatial and Temporal Ca2+ Signals in Arabidopsis Plants

Ca2+ signaling regulates diverse biological processes in plants. Here we present approaches for monitoring abiotic stress induced spatial and temporal Ca2+ signals in Arabidopsis cells and tissues using the genetically encoded Ca2+ indicators Aequorin or Case12.

Developmental and environmental cues induce Ca2+ fluctuations in plant cells. Stimulus-specific spatial-temporal Ca2+ patterns are sensed by cellular Ca2+ ...

High Resolution Quantification of Crystalline Cellulose Accumulation in Arabidopsis Roots to Monitor Tissue-specific Cell Wall Modifications

Plant cells are surrounded by a cell wall, the composition of which determines their final size and shape. The cell wall is composed of a complex matrix containing polysaccharides that include cellulose microfibrils that form both crystalline structures and cellulose chains of amorphous organization. The orientation of the cellulose fibers and their concentrations dictate the mechanical properties of the cell. Several methods are used to determine the levels of crystalline cellulose, each bringing both advantages and limitations. Some can distinguish the proportion of crystalline regions within the total cellulose. However, they are limited to whole-organ analyses that are deficient in spatiotemporal information. Others relying on live imaging, are limited by the use of imprecise dyes. Here, we report a sensitive polarized light-based system for specific quantification of relative light retardance, representing crystalline cellulose accumulation in cross sections of Arabidopsis thaliana roots. In this method, the cellular resolution and anatomical data are maintained, enabling direct comparisons between the different tissues composing the growing root. This approach opens a new analytical dimension, shedding light on the link between cell wall composition, cellular behavior and whole-organ growth.

High Resolution Quantification of Crystalline Cellulose Accumulation in Arabidopsis Roots to Monitor Tissue-specific Cell Wall Modifications

Crystalline cellulose is an important constituent of the plant cell wall. However, its quantification at a cellular resolution is technically challenging. Here, we report the use of polarized light technology and root cross sections to obtain information of cell wall composition at a spatiotemporal resolution.

Plant cells are surrounded by a cell wall, the composition of which determines their final size and shape. The cell wall is composed of a complex matrix ...

Micron-scale Phenotyping Techniques of Maize Vascular Bundles Based on X-ray Microcomputed Tomography

It is necessary to accurately quantify the anatomical structures of maize materials based on high-throughput image analysis techniques. Here, we provide a 'sample preparation protocol' for maize materials (i.e., stem, leaf, and root) suitable for ordinary microcomputed tomography (micro-CT) scanning. Based on high-resolution CT images of maize stem, leaf, and root, we describe two protocols for the phenotypic analysis of vascular bundles: (1) based on the CT image of maize stem and leaf, we developed a specific image analysis pipeline to automatically extract 31 and 33 phenotypic traits of vascular bundles; (2) based on the CT image series of maize root, we set up an image processing scheme for the three-dimensional (3-D) segmentation of metaxylem vessels, and extracted two-dimensional (2-D) and 3-D phenotypic traits, such as volume, surface area of metaxylem vessels, etc. Compared with traditional manual measurement of vascular bundles of maize materials, the proposed protocols significantly improve the efficiency and accuracy of micron-scale phenotypic quantification.

We provide a novel method to improve the X-ray absorption contrast of maize tissue suitable for ordinary microcomputed tomography scanning. Based on CT images, we introduce a set of image-processing workflows for different maize materials to effectively extract microscopic phenotypes of vascular bundles of maize.

It is necessary to accurately quantify the anatomical structures of maize materials based on high-throughput image analysis techniques. Here, we provide a ...

Wide-Field, Real-Time Imaging of Local and Systemic Wound Signals in Arabidopsis

Plants respond to mechanical stresses such as wounding and herbivory by inducing defense responses both in the damaged and in the distal undamaged parts. Upon wounding of a leaf, an increase in cytosolic calcium ion concentration (Ca2+ signal) occurs at the wound site. This signal is rapidly transmitted to undamaged leaves, where defense responses are activated. Our recent research revealed that glutamate leaking from the wounded cells of the leaf into the apoplast around them serves as a wound signal. This glutamate activates glutamate receptor-like Ca2+ permeable channels, which then leads to long-distance Ca2+ signal propagation throughout the plant. The spatial and temporal characteristics of these events can be captured with real-time imaging of living plants expressing genetically encoded fluorescent biosensors. Here we introduce a plant-wide, real-time imaging method to monitor the dynamics of both the Ca2+ signals and changes in apoplastic glutamate that occur in response to wounding. This approach uses a wide-field fluorescence microscope and transgenic Arabidopsis plants expressing Green Fluorescent Protein (GFP)-based Ca2+ and glutamate biosensors. In addition, we present methodology to easily elicit wound-induced, glutamate-triggered rapid and long-distance Ca2+ signal propagation. This protocol can also be applied to studies on other plant stresses to help investigate how plant systemic signaling might be involved in their signaling and response networks.

Wide-Field, Real-Time Imaging of Local and Systemic Wound Signals in Arabidopsis

Extracellular glutamate-triggered systemic calcium signaling is critical for the induction of plant defense responses to mechanical wounding and herbivore attack in plants. This article describes a method to visualize the spatial and temporal dynamics of both these factors using Arabidopsis thaliana plants expressing calcium- and glutamate-sensitive fluorescent biosensors.

Plants respond to mechanical stresses such as wounding and herbivory by inducing defense responses both in the damaged and in the distal undamaged parts. ...

Divergence of Root Microbiota in Different Habitats based on Weighted Correlation Networks

The root microbiome plays an important role in plant growth and environmental adaptation. Network analysis is an important tool for studying communities, which can effectively explore the interaction relationship or co-occurrence model of different microbial species in different environments. The purpose of this manuscript is to provide details on how to use the weighted correlation network algorithm to analyze different co-occurrence networks that may occur in microbial communities due to different ecological environments. All analysis of the experiment is performed in the WGCNA package. WGCNA is an R package for weighted correlation network analysis. The experimental data used to demonstrate these methods were microbial community data from the NCBI (National Center for Biotechnology Information) database for three niches of the rice (Oryza sativa) root system. We used the weighted correlation network algorithm to construct co-abundance networks of microbial community in each of the three niches. Then, differential co-abundance networks among endosphere, rhizoplane and rhizosphere soil were identified. In addition, the core genera in network were obtained by the "WGCNA" package, which plays an important regulated role in network functions. These methods enable researchers to analyze the response of microbial network to environmental disturbance and verify different microbial ecological response theories. The results of these methods show that the significant differential microbial networks identified in the endosphere, rhizoplane and rhizosphere soil of rice.

Network analysis was applied to evaluate the association of various ecological microbial communities, such as soil, water and rhizosphere. Presented here is a protocol on how to use the WGCNA algorithm to analyze different co-occurrence networks that may occur in the microbial communities due to different ecological environments.

The root microbiome plays an important role in plant growth and environmental adaptation. Network analysis is an important tool for studying communities, ...

A Simple Protocol for Mapping the Plant Root System Architecture Traits

Comprehensive knowledge of plant root system architecture (RSA) development is critical for improving nutrient use efficiency and increasing crop cultivar tolerance to environmental challenges. An experimental protocol is presented for setting up the hydroponic system, plantlet growth, RSA spreading, and imaging. The approach used a magenta box-based hydroponic system containing polypropylene mesh supported by polycarbonate wedges. Experimental settings are exemplified by assessing the RSA of the plantlets under varying nutrient (phosphate [Pi]) supply. The system was established to examine the RSA of Arabidopsis, but it is readily adaptable to study other plants like Medicago sativa (Alfalfa). Arabidopsis thaliana (Col-0) plantlets are used in this investigation as an example to understand the plant RSA. Seeds are surface sterilized by treating ethanol and diluted commercial bleach, and kept at 4 &#176;C for stratification. The seeds are germinated and grown on a liquid half-MS medium on a polypropylene mesh supported by polycarbonate wedges. The plantlets are grown under standard growth conditions for the desired number days, gently picked out from the mesh, and submersed in water-containing agar plates. Each root system of the plantlets is spread gently on the water-filled plate with the help of a round art brush. These Petri plates are photographed or scanned at high resolution to document the RSA traits. The root traits, such as primary root, lateral roots, and branching zone, are measured using the freely available ImageJ software. This study provides techniques for measuring plant root characteristics in controlled environmental settings. We discuss how to (1) grow the plantlets, and collect and spread root samples, (2) obtain pictures of spread RSA samples, (3) capture the images, and (4) use image analysis software to quantify root attributes. The advantage of the present method is the versatile, easy, and efficient measurement of the RSA traits.

We use simple laboratory tools to examine the root system architecture (RSA) of Arabidopsis and Medicago. The plantlets are grown hydroponically over mesh and spread using an art brush to reveal the RSA. Images are taken using scanning or a high-resolution camera, then analyzed with ImageJ to map traits.

Comprehensive knowledge of plant root system architecture (RSA) development is critical for improving nutrient use efficiency and increasing crop cultivar ...

Lateral Root Inducible System in Arabidopsis and Maize

Summary

Explore More Videos

Chapters in this video

Preparation and Maintenance of Dorsal Root Ganglia Neurons in Compartmented Cultures

Do-It-Yourself Device for Recovery of Cryopreserved Samples Accidentally Dropped into Cryogenic Storage Tanks

Using Flatbed Scanners to Collect High-resolution Time-lapsed Images of the Arabidopsis Root Gravitropic Response

An Assay for Lateral Line Regeneration in Adult Zebrafish

Measuring Spatial and Temporal Ca²⁺ Signals in Arabidopsis Plants

High Resolution Quantification of Crystalline Cellulose Accumulation in Arabidopsis Roots to Monitor Tissue-specific Cell Wall Modifications

Micron-scale Phenotyping Techniques of Maize Vascular Bundles Based on X-ray Microcomputed Tomography

Wide-Field, Real-Time Imaging of Local and Systemic Wound Signals in Arabidopsis

Divergence of Root Microbiota in Different Habitats based on Weighted Correlation Networks

A Simple Protocol for Mapping the Plant Root System Architecture Traits