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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 ZmCesA genes involved in primary (A) and secondary (B) cell wall synthesis in the elongating maize internode. The data are averages of four biological replicates with indications of standard errors. Uniprot accession numbers for the genes are indicated in brackets. Cellulose levels in the individual sections are also indicated.
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Figure 4: Transcript levels of ZmCesA genes involved in primary (A) and secondary (B) cell wall synthesis in the elongating maize internode. The data are averages of four biological replicates with indications of standard errors. Uniprot accession numbers for the genes are indicated in brackets. Cellulose levels in the individual sections are also indicated.

Mentions: The maize genome contains at least 12 CesA genes, some of which are believed to be involved in cellulose synthesis during primary cell wall deposition (group 1), while others are involved in cellulose synthesis during secondary wall deposition (group 2) [4]. The transcript levels of representative ZmCesA genes from the primary wall group 1 were generally quite low compared with those of the secondary cell wall group 2 genes (Figure 4A cf. Figure 4B) and did not change much from the bottom to the top of the internode (Figure 4A). However, transcripts of the ZmCesA7 gene were detected at levels similar to those for the other primary wall CesA genes in the meristematic and lower elongation zone sections, but increased to relatively high levels in the transition zone and remained high throughout the maturation zone (Figure 4A).


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 ZmCesA genes involved in primary (A) and secondary (B) cell wall synthesis in the elongating maize internode. The data are averages of four biological replicates with indications of standard errors. Uniprot accession numbers for the genes are indicated in brackets. Cellulose levels in the individual sections are also indicated.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Transcript levels of ZmCesA genes involved in primary (A) and secondary (B) cell wall synthesis in the elongating maize internode. The data are averages of four biological replicates with indications of standard errors. Uniprot accession numbers for the genes are indicated in brackets. Cellulose levels in the individual sections are also indicated.
Mentions: The maize genome contains at least 12 CesA genes, some of which are believed to be involved in cellulose synthesis during primary cell wall deposition (group 1), while others are involved in cellulose synthesis during secondary wall deposition (group 2) [4]. The transcript levels of representative ZmCesA genes from the primary wall group 1 were generally quite low compared with those of the secondary cell wall group 2 genes (Figure 4A cf. Figure 4B) and did not change much from the bottom to the top of the internode (Figure 4A). However, transcripts of the ZmCesA7 gene were detected at levels similar to those for the other primary wall CesA genes in the meristematic and lower elongation zone sections, but increased to relatively high levels in the transition zone and remained high throughout the maturation zone (Figure 4A).

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