Key Stages of Flax Bast Fiber Development Through the Prism of Transcriptomics

Abstract

AbstractTranscriptome profiling is a powerful modern tool for investigating biological processes in depth. Based on genome-wide RNA-Seq data obtained for bast fibers and other tissues of growing flax plants, we characterize two key stages of fiber development—the intrusive elongation and the formation of the tertiary cell wall. The peculiarities of general cell metabolism and the molecular players that are essential for each or both of these stages are revealed. The analysis is largely based on the online platform FIBexDB that permits to characterize individual genes, compare their expression in numerous samples, and build the coexpression networks. The genes with fiber-specific and stage-specific character of expression include the genes for cell wall-related products, cytoskeleton proteins, transporters, transcription factors, and others. Well-known participants and new players involved in the biosynthesis of rhamnogalacturonan I and cellulose, components of the tertiary cell wall, are discussed in detail. Genes for proteins that could be considered specific markers of the tertiary cell wall deposition in flax fibers are presented, such as fasciclin-like arabinogalactan proteins, chitinase-like proteins, galactosidases, and rhamnogalacturonan lyases. The possible association of fiber yield and quality with the expression levels of genes for defined products is outlined. The levels of various miRNAs are discussed in relation to their potential target amounts. The accumulated and systemized information in this chapter provides indispensable knowledge to understand fiber development at the molecular level in order to harness the plant for the design of desirable traits and to advance fundamental aspects of plant cell growth and cell wall formation study.KeywordsFlaxFiberTranscriptomeIntrusive growthTertiary cell wallRhamnogalacturonan ICelluloseTranscription factorsmiRNA