Identification of miRNAs Interacting with Abscisic Acid to Regulate Fatty Acid Metabolism

Abstract

Fatty acids are synthesized and stored in seeds during development in Brassica napus. Understanding the molecular mechanism behind fatty acid biosynthesis during seed development is a crucial research objective. In this study, we proved that exogenous application of abscisic acid (ABA) to the siliques can efficiently improve unsaturated fatty acid content in rapeseeds. Then we identified a total of 97 novel microRNAs (miRNAs) and 211 known miRNAs in the seeds of B. napus by high-throughput sequencing. Among them, a total of 23 differentially expressed miRNAs were observed between siliques treated with ABA and the control group. These 23 miRNAs regulated target genes that were involved in lipid metabolism through the integration of gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations. Moreover, we validated selected members from these miRNAs and their predicted targets through quantitative RT-PCR. Among these, miR172a, miR395a, and novel13 were significantly down-regulated after ABA treatment, while novel3 was significantly up-regulated. Notably, the predicted target genes of miR172a and miR395a, namely, KAS I and DGAT, play crucial roles in fatty acid synthesis and exhibit up-regulated expression in response to ABA. Our findings suggest that a variety of miRNAs interact with ABA to regulate fatty acid biosynthesis, highlighting the important roles played by miRNAs in the process of fatty acid biosynthesis during seed development.