Name: lateral root inducible system in arabidopsis and maize
Uploaded: 2016-01-14T16:00:00
Description: Watch this Scientific Journal Video about Lateral Root Inducible System in Arabidopsis and Maize at JoVE.com

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 ...

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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

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 ...

The overall goal of the lateral root inducible system is to synchronously induce the initiation of lateral roots in plants using hormone treatments. Plant roots are the hidden and are known to be extremely difficult to study. We have developed an in vitro system that allows to study the process of lateral root initiation on a cytological, histological, and molecule level.Generally, scientists new to this method might struggle because the plants have not grown into proper contact with the medium, preventing a homogenous induction of the lateral roots. Visual demonstration of this method helps showing the critical steps that should be taken into account to ensure a homogenous induction. Although this system was originally developed in a little plant Arabidopsis, it can also be applied to other systems such as maize, rice, or barley.To begin, apply a 20-micron nylon mesh to NPA-supplemented growth medium using a pair of sterile tweezers. Gently push the mesh onto the growth medium using a drigalski to make sure it is in good contact with the medium. Next, pinch a sterile toothpick into the agar to create a sticky surface on the toothpick.Use the toothpick to evenly distribute a batch of gas-sterilized seeds onto the prepared plates. Seal the plates with breathable adhesive tape and store them at four degrees Celsius in the dark for at least two days and a maximum of one week. This is needed for stratification and ensures synchronized and efficient germination.On the third day, move the plates to the growth room for two days of germination followed by three days of growth at an angle of 80 to 90 degrees. On day eight, identify the roots that have grown entirely in contact with the mesh and on the contrary, roots that are not in contact with the mesh. Remove all the seedlings which roots are not in contact with the mesh.Transfer the seedling-containing meshes to plates supplemented with 10 micromolar NAA. Once on the plate, skim the mesh over the medium surface if necessary to make sure that it is in good contact with the growth medium. To ensure a homogenous induction in all seedlings, it is important to discard the seedlings that have not grown into contact with the mesh on NPA-supplemented medium and to properly skim the mesh if necessary on NAA-supplemented medium.Seal the new plates with breathable tape and place them in the growth room in a vertical position for the desired amount of time after induction. When ready to collect the samples, 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. We will now show some steps of the lateral root inducible system in maize.Begin by sterilizing the maize kernels by first placing the necessary number of kernels into a sterile glass beaker. Then, add 100 milliliters of 6%sodium hypochlorite in water to the beaker and add a magnetic stir bar. Place the beaker on a magnetic stirrer and stir at a low speed for five mintues at room temperature.Gently remove the bleach solution. Replace it with 100 milliliters of fresh sterile water and rinse the kernels for five minutes. Repeat this step five times.Put on a pair of gloves and tear off two stretches of hand paper towels, placing them on top of each other on a clean surface. Then, fold the sheets double over the length. Use tweezers to distribute 10 kernels approximately two centimeters from the top, over the entire length of the paper while keeping an interspace distance of eight centimeters between each kernel and eight centimeters free at both ends.Make sure the radical of the kernel is facing down and toward the paper. Gently roll the paper over the length while keeping the seeds in place. Spraying the paper with sterile water can facilitate this step if necessary.Put the rolls into sterilized glass tubes and combine additional tubes into the rack. Pour 125 milliliters of a 50 micromolar NPA solution over the paper roll in the tube. The paper roll will absorb the solution and become completely soaked.Place the paper roll system in a growth cabinet for three days. Make sure that the paper rolls remain soaked during incubation by adding extra NPA solution as needed. To ensure homogenous induction of lateral root initiation, it is important to check that the paper rolls remain moisturized in NPA solution, but that the roots are not submerged in the liquid itself.After three days on NPA, the maize seedling has a small shoot and a root of approximately two to three centimeters. On day four, gently squeeze out most of the remaining NPA solution from the paper rolls and place the rolls in sterile water until they become saturated. After about five minutes, gently squeeze out most of the water from the paper rolls.Repeat the wash step three times. Following the final rinse, squeeze out most of the water and place it back into the tube. Pour a 50 micromolar solution of NAA over the paper rolls in the tubes until they become completely soaked.Then, place the paper roll system in the growth cabinet for the desired duration after induction. In comparison to oxen response marker line pDR5-GUS seedlings that haven't grown on NAA or have grown for one hour on NAA, the seedlings grown for two hours on NAA show an oxen response which is one of the first events triggering lateral root initiation. These divisions start moving up from the tip starting at around two hours, and increase with prolonged exposure to NAA.Using the cell cycle marker line pCYCB1;1-Gus, the first cell divisions that lead to lateral root formation can be seen starting at around six hours after the start of NAA treatment. Microarrays and quantitative rt-PCR can be used to evaluate expression of various genes throughout the different regions of the Arabidopsis and maize roots during lateral root induction. In both Arabidposis and maize, when the plants grow for a longer time, the induced divisions will give rise to the development and outgrowth of lateral roots.As proof of concept for the system on maize, here are seedlings grown under different conditions for comparison. Seedlings grown for 10 days on water have lateral roots that didn't initiate synchronously and are widely spaced along the axis. Seedlings grown for 10 days on NPA contain no lateral roots at all.Seedlings grown for three days on NPA, followed by an NAA treatment, show a massive and synchronized induction of lateral roots. In this video we have shown you how to set up a lateral root inducible system that has turned out to be very essential in the discovery of fundamental new insights into the process of root branching. We have shown you how it works for Arabidopsis and maize, but it can easily be adapted to other plant species of choice.Good luck.

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SCIENTISTS IN ACTION

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 ...

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 ...

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 ...

Visualization of Cellular Interactions Between the Maize Sheaths and Fungi

Detached Maize Sheaths for Live-Cell Imaging of Infection by Fungal Foliar Maize Pathogens

We have optimized a protocol to inoculate maize leaf sheaths with hemibiotrophic and necrotrophic foliar pathogenic fungi. The method is modified from one originally applied to rice leaf sheaths and allows direct microscopic observation of fungal growth and development in living plant cells. Leaf sheaths collected from maize seedlings with two fully emerged leaf collars are inoculated with 20 &#181;L drops of 5 x 105 spores/mL fungal spore suspensions and incubated in humidity chambers at 23 &#176;C under continuous fluorescent light. After 24-72 h, excess tissue is removed with a razor blade to leave a single layer of epidermal cells, an optically clear sample that can be imaged directly without the necessity for chemical fixation or clearing. Plant and fungal cells remain alive for the duration of the experiment and interactions can be visualized in real-time. Sheaths can be stained or subjected to plasmolysis to study the developmental cytology and viability of host and pathogen cells during infection and colonization. Fungal strains transformed to express fluorescent proteins can be inoculated or co-inoculated on the sheaths for increased resolution and to facilitate the evaluation of competitive or synergistic interactions. Fungal strains expressing fluorescent fusion proteins can be used to track and quantify the production and targeting of these individual proteins in planta. Inoculated sheath tissues can be extracted to characterize nucleic acids, proteins, or metabolites. The use of these sheath assays has greatly advanced the detailed studies of the mechanisms of fungal pathogenicity in maize and also of fungal protein effectors and secondary metabolites contributing to pathogenicity.

Author Spotlight: Investigating Fungal Pathogenicity Mechanisms in Maize 

This manuscript details an optimized inoculation protocol that uses detached maize leaf sheaths for reproducible cytological, physiological, and molecular studies of maize interactions with fungal plant pathogens. The leaf sheaths facilitate real-time observation of cellular interactions between the living plant and fungus in unfixed tissues.

We have optimized a protocol to inoculate maize leaf sheaths with hemibiotrophic and necrotrophic foliar pathogenic fungi. The method is modified from one ...

Semihydroponic Glass Jar System for Exudate Analysis in Multiple Plant Species

A Versatile Glass Jar System for Semihydroponic Root Exudate Profiling

Root exudates shape the plant-soil interface, are involved in nutrient cycling&#160;and modulate interactions with soil organisms. Root exudates are dynamic and shaped by biological, environmental, and experimental conditions. Due to their wide diversity and low concentrations, accurate exudate profiles are challenging to determine, even more so in natural environments where other organisms are present, turning over plant-derived compounds and producing additional compounds themselves. The semihydroponic glass jar experimental system introduced here allows control over biological, environmental, and experimental factors. It allows the growth of various phylogenetically distinct plant species for up to several months with or without microbes, in a variety of different growth media. The glass-based design offers a low metabolite background for high sensitivity and low environmental impact as it can be reused. Exudates can be sampled nondestructively, and conditions can be altered over the course of an experiment if desired. The setup is compatible with mass spectrometry analytics and other downstream analytical procedures. In summary, we present a versatile growth system suited for sensitive root exudate analysis in a variety of conditions.

Author Spotlight: Exploring Plant-Microbe Interactions Through Root Exudates in a Novel Growth System 

We present a protocol for a glass-based, semihydroponic experimental system supporting the growth of a variety of phylogenetically distinct plants with or without microbes. The system is compatible with different growth media and permits nondestructive root exudate sampling for downstream analysis.

Root exudates shape the plant-soil interface, are involved in nutrient cycling&#160;and modulate interactions with soil organisms. Root exudates are ...

Agrobacterium-Mediated Hairy Root Induction and Regeneration in Plants

Hairy Root Transformation and Regeneration in Arabidopsis thaliana and Brassica napus

Hairy root transformation represents a versatile tool for plant biotechnology in various species. Infection by an Agrobacterium strain carrying a Root-inducing (Ri) plasmid induces the formation of hairy roots at the wounding site after the transfer of T-DNA from the Ri plasmid into the plant genome. The protocol describes in detail the procedure of the injection-based hairy root induction in Brassica napus DH12075 and Arabidopsis thaliana Col-0. The hairy roots may be used to analyze a transgene of interest or processed for the generation of transgenic plants. Regeneration medium containing cytokinin 6-benzylaminopurine (5 mg/L) and auxin 1-naphthaleneacetic acid (8 mg/L) successfully elicits shoot formation in both species. The protocol covers the genotyping and selection of regenerants and T1 plants to obtain plants carrying a transgene of interest and free of T-DNA from the Ri plasmid. An alternative process leading to the formation of a composite plant is also depicted. In this case, hairy roots are kept on the shoot (instead of the natural roots), which enables the study of a transgene in hairy root cultures in the context of the whole plant.

Author Spotlight: Optimizing Hairy Root-Based Transformation Protocols for Enhanced Efficiency in Brassicaceae

The protocol describes hairy root induction using Arabidopsis primary inflorescence stems and Brassica napus hypocotyls. The hairy roots can be cultured and used as explants to regenerate transgenic plants.

Hairy root transformation represents a versatile tool for plant biotechnology in various species. Infection by an Agrobacterium strain carrying a ...

High-Resolution Imaging of Chlorophyll Biosynthesis in Arabidopsis Seedling

Non-invasive Assay for Chlorophyll Biosynthesis Kinetics Determination during Early Stages of Arabidopsis De-etiolation

Chlorophyll biosynthesis is a hallmark of de-etiolation, one of the most dramatic stages in the plant life cycle. The tightly controlled and highly dynamic process of chlorophyll biosynthesis is triggered during the shift from the dark to the light in flowering plants. At the moment when etiolated seedlings are exposed to the first traces of sunlight, rapid (in order of seconds) conversion of protochlorophyllide into chlorophyllide is mediated by unique light-accepting protein complexes, leading via subsequent metabolic steps to the production of fully functional chlorophyll. Standard techniques for chlorophyll content analysis include pigment extraction from detached plant tissues, which does not apply to studying such fast processes. To investigate chlorophyll kinetics in vivo with high accuracy and spatiotemporal resolution in the first hours after light-induced de-etiolation, an instrument and protocol were developed. Here, we present a detailed procedure designed for statistically robust quantification of chlorophyll in the early stages of Arabidopsis de-etiolation.

Author Spotlight: Non-Invasive High-Resolution Measurement of Chlorophyll Synthesis During De-Etiolation

Here, we describe an advanced tool designed for chlorophyll biosynthesis monitoring during the early stages of Arabidopsis seedling de-etiolation. The novel methodology provides non-invasive real-time chlorophyll fluorescence imaging at high spatial and temporal resolution.

Chlorophyll biosynthesis is a hallmark of de-etiolation, one of the most dramatic stages in the plant life cycle. The tightly controlled and highly ...

Hydroponic System Preparation and Root Exudate Collection in Plants for Root Profiling

To begin, add 150 milliliters of clean five-millimeter glass beads to the clean jar and close the lid. Cover the closed jar with enough aluminum foil to conceal the lid to jar junction and autoclave at 121 degrees Celsius for 20 minutes. When the seedlings are ready to transfer into the jar on the sterile bench, remove the aluminum foil and lid of the jar.Add 35 milliliters of half-strength Murashige and Skoog medium of pH 5.7 to 5.9 to the jar, and stir the beads to coat evenly with the medium. Introduce three to five seedlings into the jar, ensuring the root systems are placed between the glass beads. Adjust the beads with sterile forceps or spoons to cover the roots and lift the leaves out of the medium.Secure two strips of 1.25 centimeter micropore tape across the top of the jar and gently place the lid on top. Seal the gap between the lid and jar with 2.5-centimeter micropore tape to maintain sterility while permitting air exchange, and place the jar into a growth chamber. When the plants reach the desired age, remove the micropore tape and lid from the jar.Aliquot 20 microliters of growth medium onto LB Agar Plate for sterility testing. Using a 25-milliliter volumetric pipette, remove as much growth medium as possible without damaging the roots. Add 50 milliliters of collection medium along the jar wall to prevent wetting the leaves.Close the jar with a lid and incubate in sterile conditions for two hours. After incubation, remove the desired amount of collection medium into tubes. Measure the weight of the root and shoot from the plant in one jar to normalize the root exudates by plant weight.Arabidopsis thaliana plants looked healthy across two different laboratories. The glass jar system proved adaptable for various plant species and developmental stages. Wheat had the highest chute weights, followed by sorghum and tomato.While sorghum had the highest root weights, followed by wheat and Medicago truncatula. Inoculation of Arabidopsis thaliana with commensal bacteria did not alter the plant phenotype, and inoculated bacteria persisted in the system for at least 12 days with a slight increase in colony-forming units.