Genome-wide analysis of lncRNAs points to their roles in the modulation of developmental regulator expression during plant male germline development

Abstract

AbstractLncRNAs can function in regulating of gene expression, but their roles as essential regulators of developmental processes and organismal phenotypes remain largely unclear. Especially the roles of lncRNAs in plants are largely unexplored. However, it has been proposed that plant lncRNAs act as regulators of protein-coding genes during development and that the similar roles of animal and plant lncRNAs result from convergent evolution. Since pollen development follows an established program with well-defined and characterized stages, we have used it as a model for studying plant lncRNAs and their roles in reproductive development. We investigated of lncRNA expression and function during pollen formation in field mustard (Brassica rapa). Reference-based transcriptome assembly performed to update the existing genome annotation identified novel expressed protein-coding genes and long non-coding RNAs (lncRNAs), including 4,347 long intergenic non-coding RNAs (lincRNAs, 1058 expressed) and 2,045 lncRNAs overlapping protein-coding genes on the opposite strand (lncNATs, 780 expressed). The analysis of expression profiles reveals that lncRNAs are significant and stage-specific contributors to the gene expression profile of developing pollen. Gene co-expression networks accompanied by genome location analysis identified 38 cis-acting lincRNA, 31 cis-acting lncNAT, 7 trans-acting lincRNA and 14 trans-acting lncNAT to be substantially co-expressed with target protein-coding genes involved in biological processes regulating pollen development and male lineage specification. These findings provide a foundation for future research aiming at developing strategies to employ lncRNAs as regulatory tools for gene expression control during reproductive development.