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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 involved in sugar nucleotide interconversions in the elongating maize internode. These include UDP-xylose synthase (UXS), UDP-glucose epimerase (UGE) and UDP-glucose pyrophosphorylase (UGPP) genes. Cellulose levels are also indicated.
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Figure 8: Transcript levels of genes involved in sugar nucleotide interconversions in the elongating maize internode. These include UDP-xylose synthase (UXS), UDP-glucose epimerase (UGE) and UDP-glucose pyrophosphorylase (UGPP) genes. Cellulose levels are also indicated.

Mentions: Biosynthesis of the major cell wall polysaccharides in maize stalks requires sugar nucleotides such as UDP-Glc, UDP-GlcA, UDP-Xyl and UDP-Ara, and the transcript levels of important genes in the interconversion pathways were therefore examined in the maize internode sections. The UDP-Glc pyrophosphorylase (UGPP) enzyme controls the entry of carbon into the sugar nucleotide pools through the formation of UDP-Glc from glucose 1-phosphate and UTP. Transcript levels of one of the maize UGPP genes (Q6Y643) was very high in the meristematic tissues of Section S1, and increased substantially in Sections S2–S4 of the elongation and transition zones (Figure 8). Another important gene in the sugar nucleotide interconversion pathways is UDP-Xyl synthase (UXS), which catalyses the irreversible decarboxylation of UDP-GlcA to form UDP-Xyl. The UXS enzyme therefore commits carbon to the formation of pentose sugars, which are major constituents of the maize GAX polysaccharide. Transcript levels of one of UXS genes (Q6J683) were about 5-fold lower than those for the UGPP gene, but showed a similar pattern along the internode. The UXS gene transcripts also peaked in Sections S3 and S4 of the transition zone (Figure 8).


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 involved in sugar nucleotide interconversions in the elongating maize internode. These include UDP-xylose synthase (UXS), UDP-glucose epimerase (UGE) and UDP-glucose pyrophosphorylase (UGPP) genes. Cellulose levels are also indicated.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 8: Transcript levels of genes involved in sugar nucleotide interconversions in the elongating maize internode. These include UDP-xylose synthase (UXS), UDP-glucose epimerase (UGE) and UDP-glucose pyrophosphorylase (UGPP) genes. Cellulose levels are also indicated.
Mentions: Biosynthesis of the major cell wall polysaccharides in maize stalks requires sugar nucleotides such as UDP-Glc, UDP-GlcA, UDP-Xyl and UDP-Ara, and the transcript levels of important genes in the interconversion pathways were therefore examined in the maize internode sections. The UDP-Glc pyrophosphorylase (UGPP) enzyme controls the entry of carbon into the sugar nucleotide pools through the formation of UDP-Glc from glucose 1-phosphate and UTP. Transcript levels of one of the maize UGPP genes (Q6Y643) was very high in the meristematic tissues of Section S1, and increased substantially in Sections S2–S4 of the elongation and transition zones (Figure 8). Another important gene in the sugar nucleotide interconversion pathways is UDP-Xyl synthase (UXS), which catalyses the irreversible decarboxylation of UDP-GlcA to form UDP-Xyl. The UXS enzyme therefore commits carbon to the formation of pentose sugars, which are major constituents of the maize GAX polysaccharide. Transcript levels of one of UXS genes (Q6J683) were about 5-fold lower than those for the UGPP gene, but showed a similar pattern along the internode. The UXS gene transcripts also peaked in Sections S3 and S4 of the transition zone (Figure 8).

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