Poplar carbohydrate-active enzymes. Gene identification and expression analyses

Area of Science:

• Plant genomics
• Biochemistry
• Molecular biology

Background:

• Carbohydrate-active enzymes (CAZymes) are essential for modifying carbohydrate structures.
• The Populus trichocarpa genome contains a large repertoire of CAZyme genes.
• Comparative analysis with Arabidopsis reveals unique adaptations in poplar's CAZyme gene families.

Purpose of the Study:

• To identify and annotate all carbohydrate-active enzyme (CAZyme) genes in the Populus trichocarpa genome.
• To analyze the expression patterns of CAZyme genes across various poplar tissues.
• To compare poplar CAZyme gene complements and expression with those of Arabidopsis.

Main Methods:

• Genome-wide identification and annotation of CAZyme genes using sequence homology.
• Analysis of expressed sequence tags (ESTs) and microarray data for gene expression profiling.
• Comparative genomics between Populus and Arabidopsis.

Main Results:

• Over 1,600 CAZyme genes were identified in Populus, 1.6 times more than in Arabidopsis.
• Poplar exhibits an overrepresentation of GT1 family genes and underrepresentation of xylan/pectin families compared to Arabidopsis.
• CAZyme gene expression is widespread across tissues, with specific enrichment in wood-forming tissues for xylogenesis-related enzymes.
• Starch metabolism genes are downregulated during wood formation but upregulated in dormant meristems.

Conclusions:

• Poplar's CAZyme gene repertoire is expanded and differentially regulated compared to Arabidopsis, reflecting adaptations to woody growth.
• CAZymes play a vital role in cell wall matrix metabolism throughout poplar tissues, particularly during xylogenesis.
• Distinct transcriptomic profiles highlight tissue-specific functions and seasonal regulation of CAZymes in poplar.