Subunits of Cellulose Synthase Are Preferentially Co-expressed in Storage Parenchyma and Rind of Sugarcane With Transcripts for Specific COBRA-like and Other Cell-Wall Metabolism-Related Proteins

Sugarcane accumulates high concentrations of sucrose in the mature stem, with numerous physiological processes in maturing stem tissue both directly and indirectly involved. A considerable portion of carbohydrate metabolism is also devoted to cell wall synthesis and fibre production. We have previously identified differentially expressed transcripts correlated with sucrose accumulation and fibre production in various internodes of the sugarcane stem. In this study, we have extended this work further by profiling dissected tissues of stem sucrose storage parenchyma, vascular bundles and rind from field-grown commercial sugarcane harvested at maturity. Significant differences in the expression of transcripts corresponding to various subunits of cellulose synthase between these different tissues are reported and these are correlated with differential expression patterns for transcripts of specific COBRA-like proteins and other proteins with acknowledged roles in cell wall metabolism. We also report an unexpected paucity in expression of these transcripts in vascular bundles. The different cell wall structure and time of development in each of the three tissues profiled is of increasing interest as the fibre component of sugarcane is explored for commercial value. Additional insights into the transcript activity of these tissues within the maturing stem of sugarcane will also be discussed.