Analysis of public RNA-seq data in studies of flax fiber biogenesis

In this work we used publicly available raw RNA-seq data to elucidate mechanisms of flax fiber biogenesis by measuring expression of cell-wall related genes (cellulose synthase, cellulose synthase-like and chitinase-like genes) in stem of flax (Linum usitatissimum cv. Bethune). Using public RNA-sequence data we have quantified and characterised the expression of the specific cell-wall genes in the top, middle and bottom parts of the Bethune flax stem. The most prominent findings are: Secondary cell-wall cellulose synthase (CesA) genes are expressed differentially in phloem and xylem in all parts of Bethune stem, in contrast with primary cell-wall cellulose synthase genes. Total expression level of cellulose synthase-like (Csl) genes is tissue invariant (although, CslG and CslE are differentially expressed) and smaller than the total expression of cellulose synthase genes. The CslD2D3 subgroup dominates total expression of CslD genes in both xylem and phloem. Expression levels of all expressed chitinase-like (Ctl) genes are tissue dependent in all parts of stem. Total expression level of chitinase-like genes is much higher than expression of cellulose synthase and cellulose synthase-like genes in both tissues.