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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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Transcript levels of genes implicated in GAX synthesis, including families GT43 (A), GT8, GT47 and GT61 (B) in the elongating maize internode. Statistical treatment was as for Figure 4.
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Figure 6: Transcript levels of genes implicated in GAX synthesis, including families GT43 (A), GT8, GT47 and GT61 (B) in the elongating maize internode. Statistical treatment was as for Figure 4.

Mentions: In addition to the GT2 genes described in the sections above, several other glycosyl transferase (GT) gene families have been implicated in cell wall polysaccharide biosynthesis. In particular, members of the GT8, GT43, GT47 and GT61 (http://www.cazy.org/) [35] families of genes are believed to be involved in GAX synthesis in higher plants [36-41]. Accordingly, members of these gene families that were represented on the microarray were monitored in the ten sections along the 10th maize internode. Of these, transcript levels were highest for the two GT43 genes (Figure 6A) and transcript abundance generally peaked in Sections S4 to S6, which include the elongation and transition zones, but in some cases transcripts were high in the lower sections (Figure 6A). Levels of transcripts for the GT8, GT47 and GT61 genes were relatively low in all sections of the internode (Figure 6B).


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)

Transcript levels of genes implicated in GAX synthesis, including families GT43 (A), GT8, GT47 and GT61 (B) in the elongating maize internode. Statistical treatment was as for Figure 4.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Transcript levels of genes implicated in GAX synthesis, including families GT43 (A), GT8, GT47 and GT61 (B) in the elongating maize internode. Statistical treatment was as for Figure 4.
Mentions: In addition to the GT2 genes described in the sections above, several other glycosyl transferase (GT) gene families have been implicated in cell wall polysaccharide biosynthesis. In particular, members of the GT8, GT43, GT47 and GT61 (http://www.cazy.org/) [35] families of genes are believed to be involved in GAX synthesis in higher plants [36-41]. Accordingly, members of these gene families that were represented on the microarray were monitored in the ten sections along the 10th maize internode. Of these, transcript levels were highest for the two GT43 genes (Figure 6A) and transcript abundance generally peaked in Sections S4 to S6, which include the elongation and transition zones, but in some cases transcripts were high in the lower sections (Figure 6A). Levels of transcripts for the GT8, GT47 and GT61 genes were relatively low in all sections of the internode (Figure 6B).

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