MicroRNA and regulation of auxin and cytokinin signalling during post-mowing regeneration of winter wheat (Triticum aestivum L.)

Abstract

Winter wheat not only provides adequate fresh forage grass in winter, but also ensures ample grain production in summer. The mechanisms underlying the regeneration of winter wheat after mowing or grazing are not well understood. In this study, the miRNA expression profile of winter wheat was determined using RNA sequencing and the endogenous auxin and cis-zeatin concentrations, as well as the expression of related miRNA-targeted genes, were measured. During the post-mowing regeneration of winter wheat, the concentrations of endogenous indole-3-acetic acid (IAA), methyl indole-3-acetate (ME-IAA), and indole-3-carboxaldehyde (ICA) decreased, while those of cis-zeatin (cZ) increased. Moreover, 15 novel miRNAs and three known miRNAs were found to be involved in the synthesis and signalling transduction of auxins and cytokinins (CKs). Among these miRNAs, miR1153-y, miR5059-x, miR2916-x, novel-miR1532–3p, novel-miR1060–3p, and novel-miR0890–3p, were found to be negatively correlated with the expression of their target genes including auxin response GH3.7, auxin response factor (ARF), type-A two-component response regulator (A-ARR), aldehyde dehydrogenase (ALDH), and O-glucosyltransferase (CISZOG). Furthermore, miR1153-y was identified as mediating the cleavage of GH3.7 by RACE assay. In turn, these genes inhibited the biosynthesis and signalling of IAA and activated CK signal transduction, resulting in the rapid regeneration of mowed winter wheat. This study revealed that some miRNAs exert a positive regulatory effect on the post-mowing regeneration of winter wheat by controlling the synthesis and signal transduction of IAA and CK, and our founding will aid developments in biotechnology aimed at improving the post-mowing regeneration ability of winter wheat.