We are thankful to Sabin Russell for editing assistance. This work was part of the DOE Joint BioEnergy Institute (http://www.jbei.org) supported by the U. S. Department of Energy, Office of Science, Office of Biological and Environmental Research, through contract DE-AC02-05CH11231 between Lawrence Berkeley National Laboratory and the U.S. Department of Energy.

1. Stem Embedding
<ol>
	<li>Make a 7% agarose solution in water (7 g of electrophoresis-grade agarose in 100 ml distilled water). Dissolve the agarose by autoclaving for 20 min or by microwaving for 20 min at lowest intensity (e.g., 10% intensity of a 1,250 watt&#160;microwave).</li>
	<li>Prepare a homemade mold for embedding the stems using plastic vials.
	<ol>
		<li>Using a razor blade, cut off the conical bottom of a 2 ml screw-cap microcentrifuge tube (Part A). With a syringe needle, puncture a hole in the...

<ol>
	<li>Boerjan, W., Ralph, J., Baucher, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lignin+biosynthesis.">Lignin biosynthesis.</a> Annual review of plant biology. 54, 519-546 (2003).</li><li>Vanholme, R., Demedts, B., Morreel, K., Ralph, J., Boerjan, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lignin+biosynthesis+and+structure.">Lignin biosynthesis and structure.</a> Plant physiology. 153, 895-905 (2010).</li><li>Humphreys, J. M., Chapple, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rewriting+the+lignin+roadmap.">Rewriting the lignin roadmap.</a> Current opinion in plant biology. 5, 224-229 (2002).</li><li>Adler, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lignin+chemistry&#8212;past,+present+and+future.">Lignin chemistry&#8212;past, present and future.</a> Wood Sci. Technol. 11, 169-218 (1977).</li><li>Brien, T. P., Feder, N., 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=Polychromatic+Staining+of+Plant+Cell+Walls+by+Toluidine+Blue.">Polychromatic Staining of Plant Cell Walls by Toluidine Blue.</a> 59, 368-373 (1964).</li><li>Mori, B., Bellani, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+staining+for+cellulosic+and+modified+plant+cell+walls.">Differential staining for cellulosic and modified plant cell walls.</a> Biotechnic &amp; histochemistry: official publication of the Biological Stain Commission. 71, 71-72 (1996).</li><li>Maeda, H., Ishida, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specificity+of+binding+of+hexopyranosyl+polysaccharides+with+fluorescent+brightener.">Specificity of binding of hexopyranosyl polysaccharides with fluorescent brightener.</a> Journal of biochemistry. 62, 276-278 (1967).</li><li>Wood, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specificity+in+the+interaction+of+direct+dyes+with+polysaccharides.">Specificity in the interaction of direct dyes with polysaccharides.</a> Carbohydrate Research. 85, 271-287 (1980).</li><li>Hughes, J., 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=The+use+of+an+optical+brightener+in+the+study+of+plant+structure.">The use of an optical brightener in the study of plant structure.</a> Stain technology. 50, 319-329 (1975).</li><li>Verbelen, J. P., Kerstens, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polarization+confocal+microscopy+and+congo+red+fluorescence:+a+simple+and+rapid+method+to+determine+the+mean+cellulose+fibril+orientation+in+plants.">Polarization confocal microscopy and congo red fluorescence: a simple and rapid method to determine the mean cellulose fibril orientation in plants.</a> Journal of microscopy. 198, 101-107 (2000).</li><li>Anderson, C. T., Carroll, A., Akhmetova, L., Somerville, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+imaging+of+cellulose+reorientation+during+cell+wall+expansion+in+Arabidopsis+roots.">Real-time imaging of cellulose reorientation during cell wall expansion in Arabidopsis roots.</a> Plant physiology. 152, 787-796 (2010).</li><li>Liljegren, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phloroglucinol+Stain+for+Lignin.">Phloroglucinol Stain for Lignin.</a> Cold Spring Harbor Protocols. , (2010).</li><li>Nakano, J., Meshitsuka, G., lin, S., Dence, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Detection of Lignin Methods in Lignin Chemistry. , (1992).</li><li>Sibout, R., 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=CINNAMYL+ALCOHOL+DEHYDROGENASE-C+and+-D+are+the+primary+genes+involved+in+lignin+biosynthesis+in+the+floral+stem+of+Arabidopsis.">CINNAMYL ALCOHOL DEHYDROGENASE-C and -D are the primary genes involved in lignin biosynthesis in the floral stem of Arabidopsis.</a> The Plant cell. 17, 2059-2076 (2005).</li><li>Teather, R. M., Wood, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+Congo+red-polysaccharide+interactions+in+enumeration+and+characterization+of+cellulolytic+bacteria+from+the+bovine+rumen.">Use of Congo red-polysaccharide interactions in enumeration and characterization of cellulolytic bacteria from the bovine rumen.</a> Applied and environmental microbiology. 43, 777-780 (1982).</li><li>Yeung, 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+beginner's+guide+to+the+study+of+plant+structure.">A beginner's guide to the study of plant structure.</a> Proceedings of the 19th Workshop/Conference of the Association for Biology Laboratory Education (ABLE. 19, 365-36 (1998).</li><li>Turner, S. R., Somerville, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collapsed+xylem+phenotype+of+Arabidopsis+identifies+mutants+deficient+in+cellulose+deposition+in+the+secondary+cell+wall).">Collapsed xylem phenotype of Arabidopsis identifies mutants deficient in cellulose deposition in the secondary cell wall).</a> The Plant Cell Online. 9, 689-701 (1997).</li><li>Iiyama, K., Pant, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mechanism+of+the+M&#228;ule+colour+reaction.+Introduction+of+methylated+syringyl+nuclei+into+softwood+lignin.">The mechanism of the M&#228;ule colour reaction. Introduction of methylated syringyl nuclei into softwood lignin.</a> Wood Sci. Technol. 22, 167-175 (1988).</li><li>Yang, F., 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=Engineering+secondary+cell+wall+deposition+in+plants.">Engineering secondary cell wall deposition in plants.</a> Plant biotechnology journal. 11, 325-335 (2013).</li><li>Zhong, R., Ripperger, A., Ye, Z. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ectopic+deposition+of+lignin+in+the+pith+of+stems+of+two+Arabidopsis+mutants.">Ectopic deposition of lignin in the pith of stems of two Arabidopsis mutants.</a> Plant physiology. 123, 59-70 (2000).</li><li>Chapple, C. C., Vogt, T., Ellis, B. E., Somerville, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Arabidopsis+mutant+defective+in+the+general+phenylpropanoid+pathway.">An Arabidopsis mutant defective in the general phenylpropanoid pathway.</a> The Plant cell. 4, 1413-1424 (1992).</li><li>Fagard, M., 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=PROCUSTE1+Encodes+a+Cellulose+Synthase+Required+for+Normal+Cell+Elongation+Specifically+in+Roots+and+Dark-Grown+Hypocotyls+of+Arabidopsis.">PROCUSTE1 Encodes a Cellulose Synthase Required for Normal Cell Elongation Specifically in Roots and Dark-Grown Hypocotyls of Arabidopsis.</a> The Plant Cell Online. 12, 2409-2423 (2000).</li></ol>

A. thaliana stem sections are widely used to study the organization of the cells in the secondary cell wall and to qualitatively examine the differences between wild type and transgenic plants. The commonly used techniques for sectioning the specimens are direct hand cutting; or when specimens are embedded in agarose or fixative, sectioning can be done with a vibratome or microtome. In contrast to hand cutting, the last two allow reducing the risk of producing inaccurate differences between samples that would be...

The plant cell wall holds a plethora of information within its various components: lignin, cellulose, hemicelluloses (xylan, glucuronoxylan, xyloglucan, arabinoxylan, mixed linkage glucan, or glucomannan), and pectin. Histological techniques provide important visual cues in studying differences within the secondary cell walls at organizational and cellular levels. Various histological techniques were developed and can be found in the literature, but these techniques can be challenging and time-consuming for beginners because very detailed protocols with simple visual instructions are seldom if ever available. The goal of this study is to provide simple guidelines for histological staining techniques to obtain high-quality images.
Sectioning the stem tissue is the first step in visualization of cell walls and cell shapes. Although hand-cut sections are inexpensive and take less time to prepare, use of a vibratome offers consistency and yields high-quality images. Using a vibratome allows producing better data quality by generating even sections with the same thickness, which helps to produce sharp images and reduces significantly the risk of producing inaccurate differences between samples that would be simply caused by a bad sample preparation. Using resins to fix fresh specimens can be a challenge for beginners and may still be time-consuming even for experts when an analysis needs to be done quickly. In addition, it becomes impossible to measure any biological activity with the sample when it has been embedded in a resin. One simple technique that employs agarose and a homemade mold is helpful for embedding stem tissues, and it can also be utilized in other applications requiring dissection of soft tissues. Compared to embedding specimens in resin, this method has the advantage of keeping the tissues alive and reducing sample manipulation. Sectioning tissues via a vibratome is highly precise and generates homogenous sections, which, depending on the goal of the study, can then be used with several different staining techniques.
The simplest methods to visualize lignin and other aromatics employ ultraviolet (UV) light. Excitation of aromatic-based molecules by UV light is an old technique, but it is still one of the quickest approaches for visualization of lignin. However, UV visualization actually is not ideal for lignin detection because UV light will excite other aromatics. Lignin is made up primarily of three building blocks, the monolignols (hydroxycinnamyl alcohols: coniferyl alcohol,&#160;sinapyl alcohol,&#160;and p-coumaryl alcohol)1-3. Phloroglucinol stain can provide clues to the extent of cinnamaldehydes present in the xylem, fiber, and tracheal tissues4. Phloroglucinol is a good indicator of general cinnamaldehydes and can differentiate between cinnamaldehydes and other aromatics. The sinapyl alcohol monomers can be detected and differentiated by the use of M&#228;ule stain. Toluidine blue O is a polychromatic dye and therefore has the ability to stain different elements of the cell wall in different colors5,6. The primary use of toluidine blue O is to detect pectin and lignin5,6. The advantage of using toluidine blue O is that many elements of the cell wall can be visualized in a single step. Both calcofluor white and congo red are easy to work with and can be used to visualize cellulose. Calcofluor white stains cellulose, callose, and other non-substituted or weakly substituted &#946;-glucans6-9, whereas congo red stains directly to &#946;-(1&#8594;4)-glucans and particularly to cellulose10,11. The goal of this study is to provide simple guidelines for the use of the aforementioned staining techniques to obtain high-quality images from A. thaliana stems.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>&#160;Agarose</td>
			<td>EMD</td>
			<td>MERC2125</td>
			<td>CAS Number: 9012-36-6</td>
		</tr>
		<tr>
			<td>Phloroglucinol</td>
			<td>Sigma</td>
			<td>P 3502</td>
			<td>1,3,5-trihydroxybenzene [CAS Number: 108-73-6]</td>
		</tr>
		<tr>
			<td>Hydrochloric Acid</td>
			<td>EMD</td>
			<td>HX0603-75</td>
			<td>CAS Number: 7647-01-0</td>
		</tr>
		<tr>
			<td>Ammonium hydroxide</td>
			<td>EMD</td>
			<td>AX1303-6</td>
			<td>CAS Number: 1336-21-6</td>
		</tr>
		<tr>
			<td>Toulidine Blue O</td>
			<td>Sigma</td>
			<td>T3260</td>
			<td>Blutene chloride, Tolonium Chloride [CAS Number 92-31-9]&#160;</td>
		</tr>
		<tr>
			<td>Potassium permanganate</td>
			<td>Sigma</td>
			<td>223468</td>
			<td>CAS Number 7722-64-7&#160;</td>
		</tr>
		<tr>
			<td>Ethanol 190 proof</td>
			<td>KOPTEC</td>
			<td>V1401</td>
			<td>CAS Number: 64-17-5</td>
		</tr>
		<tr>
			<td>Congo Red</td>
			<td>Sigma&#160;</td>
			<td>C6277</td>
			<td>Disodium 3,3&#39;-[[1,1&#39;-biphenyl]-4,4&#39;-diylbis(azo)]bis(4-aminonaphthalene 1-sulphonate) [CAS Number 573-58-0 ]</td>
		</tr>
		<tr>
			<td>Fluorescent Brightener 28/ Calcofluor White Stain</td>
			<td>Sigma</td>
			<td>F3543&#160;</td>
			<td>4,4&#39;-Bis[4-[bis(2-hydroxyethyl)amino]-6-anilino-1,3,5-triazin-2-yl]amino]stilbene-2,2&#39;-disulphonic acid [CAS Number 4404-43-7]&#160;</td>
		</tr>
		<tr>
			<td>Vibratome</td>
			<td>Leica</td>
			<td>Leica Vibrating blade microtome VT1000S</td>
			<td>http://www.leicabiosystems.com/products/sectioning/vibrating-blade-microtomes/details/product/leica-vt1000-s/</td>
		</tr>
		<tr>
			<td>Razor</td>
			<td>American Safety razor company</td>
			<td>Item # 60-0139-0000&#160;</td>
			<td>Stainless Steel Double Edge Blade (Personna Super)</td>
		</tr>
		<tr>
			<td>Screw Cap Microcentrifuge Tubes (2ml)</td>
			<td>VWR</td>
			<td>16466-044</td>
			<td></td>
		</tr>
		<tr>
			<td>Microcentrifuge Tubes (0.6ml)</td>
			<td>Axygen Scientific</td>
			<td>MCT-060-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Mitt</td>
			<td>Bel-Art</td>
			<td>380000000</td>
			<td>SCIENCEWARE&#160; Hot Hand Protector Mitt</td>
		</tr>
		<tr>
			<td>Tissue adhesive&#160;</td>
			<td>Ted Pella Inc</td>
			<td>10033</td>
			<td>Store at 4&#176;C or 20&#176;C for 3 months or longer&#160; storage&#160;</td>
		</tr>
		<tr>
			<td>Microwave</td>
			<td>Panasonic</td>
			<td>NN-SD762S</td>
			<td>PELCO Pro CA 44 Instant tissue adhesive&#160;</td>
		</tr>
		<tr>
			<td>Camera with CCD chip with no mechanical shutter&#160;</td>
			<td>Hamamatsu</td>
			<td>C4742-95</td>
			<td></td>
		</tr>
		<tr>
			<td>High speed color camera&#160;&#160;&#160;</td>
			<td>QImaging</td>
			<td>MicroPublisher 5.0 RTV</td>
			<td></td>
		</tr>
		<tr>
			<td>Camera software&#160;</td>
			<td>&#160;Molecular Devices</td>
			<td>MetaMorph version 7.7.0.0</td>
			<td></td>
		</tr>
		<tr>
			<td>Imagining anaylsis&#160;</td>
			<td>Adobe&#160;</td>
			<td>Photoshop CS4</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro Cover Glasses, Square, No.1</td>
			<td>VWR</td>
			<td>48366-067</td>
			<td>22 x 22 mm (7/8 x 7/8&#34;)-Cover glasses are corrosion-resistant and uniformly thick and flat. No. 1 thickness is 0.13 to 0.17mm.&#160;</td>
		</tr>
		<tr>
			<td>Frosted Micro Slides, 1mm</td>
			<td>VWR</td>
			<td>48312-003</td>
			<td>75 x 25 mm- 1mm</td>
		</tr>
		<tr>
			<td>TX2 Filter cube</td>
			<td>Leica</td>
			<td>11513851/11513885</td>
			<td>Filter used for Congo red analysis with a band-pass of 560/40.</td>
		</tr>
		<tr>
			<td>Parafilm M</td>
			<td>Alcan packaging</td>
			<td>BRNDPM998</td>
			<td></td>
		</tr>
	</tbody>
</table>

histochemical staining of arabidopsis thaliana secondary cell wall elements

Arabidopsis thaliana is a model organism commonly used to understand and manipulate various cellular processes in plants, and it has been used extensively in the study of secondary cell wall formation. Secondary cell wall deposition occurs after the primary cell wall is laid down, a process carried out exclusively by specialized cells such as those forming vessel and fiber tissues. Most secondary cell walls are composed of cellulose (40&#8211;50%), hemicellulose (25&#8211;30%), and lignin (20&#8211;30%). Several mutations affecting secondary cell wall biosynthesis have been isolated, and the corresponding mutants may or may not exhibit obvious biochemical composition changes or visual phenotypes since these mutations could be masked by compensatory responses. Staining procedures have historically been used to show differences on a cellular basis. These methods are exclusively visual means of analysis; nevertheless their role in rapid and critical analysis is of great importance. Congo red and calcofluor white are stains used to detect polysaccharides, whereas M&#228;ule and phloroglucinol are commonly used to determine differences in lignin, and toluidine blue O is used to differentially stain polysaccharides and lignin. The seemingly simple techniques of sectioning, staining, and imaging can be a challenge for beginners. Starting with sample preparation using the A. thaliana model, this study details the protocols of a variety of staining methodologies that can be easily implemented for observation of cell and tissue organization in secondary cell walls of plants.

Stem Embedding and Sectioning: 
The use of the homemade plastic mold to embed the stems in 7% agarose proved to be fast and easy (Figure 1). The two parts (A and B; Figure 1) of the embedded vial system make it simple to easily release the stem embedded in agarose as the agarose does not stick to the vial parts that are inert, keeping the system clean. The vials can be reused multiple times for years. The convenience of storing the embedded stem also makes the next steps easier. In ...

Watch this Scientific Journal Video about Histochemical Staining of Arabidopsis thaliana Secondary Cell Wall Elements at JoVE.com

Histochemical Staining of Arabidopsis thaliana Secondary Cell Wall Elements

Plant cell wall composition varies between tissue types and can include lignin, cellulose, hemicelluloses, and pectin. Various staining techniques have been developed to visualize differences at the cell-type level. This paper is a compilation of commonly used cell wall staining techniques.

Histochemical Staining of Arabidopsis thaliana Secondary Cell Wall Elements

Arabidopsis thaliana is a model organism commonly used to understand and manipulate various cellular processes in plants, and it has been used extensively ...

histochemical-staining-arabidopsis-thaliana-secondary-cell-wall

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39.9K visualizações.  Joint Bioenergy Institute. Plant cell wall composition varies between tissue types and can include lignin, cellulose, hemicelluloses, and pectin. Various staining techniques have been developed to visualize differences at the cell-type level. This paper is a compilation of commonly used cell wall staining techniques.