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Spatial gradients in cell wall composition and transcriptional profiles along elongating maize internodes.

Zhang Q, Cheetamun R, Dhugga KS, Rafalski JA, Tingey SV, Shirley NJ, Taylor J, Hayes K, Beatty M, Bacic A, Burton RA, Fincher GB - BMC Plant Biol. (2014)

Bottom Line: Elongating internodes can be divided into four developmental zones, namely the basal intercalary meristem, above which are found the elongation, transition and maturation zones.Rather, transcript levels of many of these genes were low in the meristematic and elongation zones, quickly increased to maximal levels in the transition zone and lower sections of the maturation zone, and generally decreased in the upper maturation zone sections.The data indicated that the enzymic products of genes involved in cell wall synthesis and modification remain active right along the maturation zone of elongating maize internodes, despite the fact that corresponding transcript levels peak earlier, near or in the transition zone.

View Article: PubMed Central - HTML - PubMed

Affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, 5064 Adelaide, South Australia, Australia. geoff.fincher@adelaide.edu.au.

ABSTRACT

Background: The elongating maize internode represents a useful system for following development of cell walls in vegetative cells in the Poaceae family. Elongating internodes can be divided into four developmental zones, namely the basal intercalary meristem, above which are found the elongation, transition and maturation zones. Cells in the basal meristem and elongation zones contain mainly primary walls, while secondary cell wall deposition accelerates in the transition zone and predominates in the maturation zone.

Results: The major wall components cellulose, lignin and glucuronoarabinoxylan (GAX) increased without any abrupt changes across the elongation, transition and maturation zones, although GAX appeared to increase more between the elongation and transition zones. Microarray analyses show that transcript abundance of key glycosyl transferase genes known to be involved in wall synthesis or re-modelling did not match the increases in cellulose, GAX and lignin. Rather, transcript levels of many of these genes were low in the meristematic and elongation zones, quickly increased to maximal levels in the transition zone and lower sections of the maturation zone, and generally decreased in the upper maturation zone sections. Genes with transcript profiles showing this pattern included secondary cell wall CesA genes, GT43 genes, some β-expansins, UDP-Xylose synthase and UDP-Glucose pyrophosphorylase, some xyloglucan endotransglycosylases/hydrolases, genes involved in monolignol biosynthesis, and NAM and MYB transcription factor genes.

Conclusions: The data indicated that the enzymic products of genes involved in cell wall synthesis and modification remain active right along the maturation zone of elongating maize internodes, despite the fact that corresponding transcript levels peak earlier, near or in the transition zone.

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Concentrations of crystalline cellulose and lignin in sections of the elongating maize internode. Cellulose (% by weight) was assayed using the acetic acid/nitric acid method of Updegraff [28] from three biological replicates. Lignin was assayed after the AIR was hydrolysed with 25% acetyl bromide in acetic acid and the residual lignin materials were weighed on filter paper and absorbance measured at 280 nm (Hatfield et al.) [29]. The data are means of three biological replicates and standard errors are indicated. Lignin was not measured in Sections S1, S3, S5, S7 or S9.
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Figure 1: Concentrations of crystalline cellulose and lignin in sections of the elongating maize internode. Cellulose (% by weight) was assayed using the acetic acid/nitric acid method of Updegraff [28] from three biological replicates. Lignin was assayed after the AIR was hydrolysed with 25% acetyl bromide in acetic acid and the residual lignin materials were weighed on filter paper and absorbance measured at 280 nm (Hatfield et al.) [29]. The data are means of three biological replicates and standard errors are indicated. Lignin was not measured in Sections S1, S3, S5, S7 or S9.

Mentions: Crystalline cellulose, as determined by acetic-nitric acid analyses [28] was relatively low in Section S1 of the elongating internode, with a value of about 20% (w/w) of the de-starched alcohol-insoluble residue (AIR) of the cell walls (Figure 1). Thereafter crystalline cellulose concentration increased to 25% w/w in Section S2 and continued to increase to about 40% w/w in the distal sections of the internode (Figure 1). Lignin concentrations followed a similar pattern along the elongating internode, showing a steady increase from about 16% w/w in the meristematic zone to about 32% w/w in the maturation zone (Figure 1). Thus, although the lignin and crystalline cellulose approximately doubled on a weight basis from the base to the top of the internode, no dramatic increases in crystalline cellulose or lignin were observed in particular regions of the internode (Figure 1). However, there was an apparent flattening of the curve between Sections S3 and S4, and the rate of increase of crystalline cellulose appeared to taper off after Section S6 (Figure 1).


Spatial gradients in cell wall composition and transcriptional profiles along elongating maize internodes.

Zhang Q, Cheetamun R, Dhugga KS, Rafalski JA, Tingey SV, Shirley NJ, Taylor J, Hayes K, Beatty M, Bacic A, Burton RA, Fincher GB - BMC Plant Biol. (2014)

Concentrations of crystalline cellulose and lignin in sections of the elongating maize internode. Cellulose (% by weight) was assayed using the acetic acid/nitric acid method of Updegraff [28] from three biological replicates. Lignin was assayed after the AIR was hydrolysed with 25% acetyl bromide in acetic acid and the residual lignin materials were weighed on filter paper and absorbance measured at 280 nm (Hatfield et al.) [29]. The data are means of three biological replicates and standard errors are indicated. Lignin was not measured in Sections S1, S3, S5, S7 or S9.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3927872&req=5

Figure 1: Concentrations of crystalline cellulose and lignin in sections of the elongating maize internode. Cellulose (% by weight) was assayed using the acetic acid/nitric acid method of Updegraff [28] from three biological replicates. Lignin was assayed after the AIR was hydrolysed with 25% acetyl bromide in acetic acid and the residual lignin materials were weighed on filter paper and absorbance measured at 280 nm (Hatfield et al.) [29]. The data are means of three biological replicates and standard errors are indicated. Lignin was not measured in Sections S1, S3, S5, S7 or S9.
Mentions: Crystalline cellulose, as determined by acetic-nitric acid analyses [28] was relatively low in Section S1 of the elongating internode, with a value of about 20% (w/w) of the de-starched alcohol-insoluble residue (AIR) of the cell walls (Figure 1). Thereafter crystalline cellulose concentration increased to 25% w/w in Section S2 and continued to increase to about 40% w/w in the distal sections of the internode (Figure 1). Lignin concentrations followed a similar pattern along the elongating internode, showing a steady increase from about 16% w/w in the meristematic zone to about 32% w/w in the maturation zone (Figure 1). Thus, although the lignin and crystalline cellulose approximately doubled on a weight basis from the base to the top of the internode, no dramatic increases in crystalline cellulose or lignin were observed in particular regions of the internode (Figure 1). However, there was an apparent flattening of the curve between Sections S3 and S4, and the rate of increase of crystalline cellulose appeared to taper off after Section S6 (Figure 1).

Bottom Line: Elongating internodes can be divided into four developmental zones, namely the basal intercalary meristem, above which are found the elongation, transition and maturation zones.Rather, transcript levels of many of these genes were low in the meristematic and elongation zones, quickly increased to maximal levels in the transition zone and lower sections of the maturation zone, and generally decreased in the upper maturation zone sections.The data indicated that the enzymic products of genes involved in cell wall synthesis and modification remain active right along the maturation zone of elongating maize internodes, despite the fact that corresponding transcript levels peak earlier, near or in the transition zone.

View Article: PubMed Central - HTML - PubMed

Affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, 5064 Adelaide, South Australia, Australia. geoff.fincher@adelaide.edu.au.

ABSTRACT

Background: The elongating maize internode represents a useful system for following development of cell walls in vegetative cells in the Poaceae family. Elongating internodes can be divided into four developmental zones, namely the basal intercalary meristem, above which are found the elongation, transition and maturation zones. Cells in the basal meristem and elongation zones contain mainly primary walls, while secondary cell wall deposition accelerates in the transition zone and predominates in the maturation zone.

Results: The major wall components cellulose, lignin and glucuronoarabinoxylan (GAX) increased without any abrupt changes across the elongation, transition and maturation zones, although GAX appeared to increase more between the elongation and transition zones. Microarray analyses show that transcript abundance of key glycosyl transferase genes known to be involved in wall synthesis or re-modelling did not match the increases in cellulose, GAX and lignin. Rather, transcript levels of many of these genes were low in the meristematic and elongation zones, quickly increased to maximal levels in the transition zone and lower sections of the maturation zone, and generally decreased in the upper maturation zone sections. Genes with transcript profiles showing this pattern included secondary cell wall CesA genes, GT43 genes, some β-expansins, UDP-Xylose synthase and UDP-Glucose pyrophosphorylase, some xyloglucan endotransglycosylases/hydrolases, genes involved in monolignol biosynthesis, and NAM and MYB transcription factor genes.

Conclusions: The data indicated that the enzymic products of genes involved in cell wall synthesis and modification remain active right along the maturation zone of elongating maize internodes, despite the fact that corresponding transcript levels peak earlier, near or in the transition zone.

Show MeSH