Expression Characteristics Analysis of CesA/Csl genes in Flax During the Fast Growing Stage

Expression characteristics of predicted CesA/Csl genes of fiber flax variety ‘Diana’ were investigated using RNA-seq data obtained during the fast-growing stage. First, flax stem anatomic analysis revealed differing developmental processes from bottom to top, with middle and lower stem fiber cells exhibiting significantly thickened cell walls. Moreover, stem cellulose/hemicellulose content exhibited positional biases, with a top-to-bottom increase in cellulose content and bottom-to-top increase in hemicellulose content observed. Most CesA/Csl genes were predominantly expressed in stems, roots, and less in leaves. The correlations between the expression levels of CesA/Csl genes and the contents of cellulose and hemicellulose were analyzed. The expression levels of LuCesA4, LuCesA8A and LuCesA8B genes showed significantly positive correlations with cellulose content (P < 0.05), while expression levels of two LuCesA3, three LuCesA6, two LuCslA2, and four LuCslC genes revealed significantly positive correlations with hemicellulose content (P < 0.05). CesA/Csl protein interaction network analysis revealed five transcription factors (TFs) that had high protein–protein interaction (PPI) scores with CesA/Csl proteins: LuNAC10 (Lus10015392), LuNAC12 (Lus10001664), LuNAM (Lus10017915), LuMyb42 (Lus10038913), LuMyb46 (Lus10027369). Therefore, these TFs may play critical regulatory roles in cellulose/hemicellulose synthesis. This study provides a theoretical foundation for investigating flax fiber cell wall synthesis and regulatory mechanisms.