Abstract
Background: Mature cotton fiber secondary wall comprises largely of cellulose (>90%) and small amounts of xylan and lignin. Little is known about the cotton fiber xylan biosynthesis by far. Results: To comprehensively survey biosynthetic enzymes involved in xylan biosynthesis in cotton fiber, the combination of the phylogenetic analysis with expression profile analysis and co-expression analyses allowed us to identify five IRX9, five IRX10, one IRX14, six IRX15, two FRA8, one PARVUS, eight GUX, four GXM, two RWA, two AXY9, 13 TBL genes. In addition, we also identified two GT61 members, two GT47 members, and two DUF579 family members whose homologs in Arabidopsis were not functionally characterized. These 55 genes were regarded as the most probable genes to be involved in fiber xylan biosynthesis. Further experimental validation of one IRX10 like and two FRA8 related genes by complementation analysis indicated that these three genes are able to partially recover the irregular xylem phenotype conferred by the xylan deficiency in the respective Arabidopsis mutant. We presume that these genes are functional orthologs of respective genes that are implicated in GX biosynthesis. Conclusion: The list of 55 cotton genes presented here provides not only a solid basis to uncover the biosynthesis of xylan in cotton fiber, but also a genetic resource potentially useful for future studies aiming at fiber improvement via biotechnological approaches.
Global identification of genes associated with xylan biosynthesis in cotton fiber
