Identification of miRNAs Involved in Male Fertility and Pollen Development in Brassica oleracea var. capitata L. by High-Throughput Sequencing

Abstract

MicroRNAs (miRNAs) are endogenously expressed, non-coding RNAs that play essential roles in numerous developmental and physiological processes in plants. However, there is a lack of data available on regulating fertility in cabbage (Brassica oleracea var. capitata L.). This study examined the expression of miRNAs during cabbage pollen development using high-throughput sequencing. Two small RNA libraries were constructed from flower buds from the cytoplasmic male-sterile (CMS) line and its maintainer fertile (MF) linee of cabbage, resulting in over 10 million sequence reads. A total of 211 new miRNAs and 7 conserved miRNAs were discovered. Eight randomly chosen miRNAs were found to have differential expression between CMS and MF, as determined by stem-loop quantitative real-time PCR (qRT-PCR). The expression patterns were similar to those detected with Illumina sequencing. Moreover, the possible targets of these putative miRNAs were inferred using a BlastX search and Gene Ontology (GO) analysis. The majority of targets have been indicated to be essential for the development of pollen or other plant parts. The discovery and characterization of miRNAs involved in pollen development in CMS and MF cabbage lines might drive research on the regulatory mechanisms of male sterility, leading to a better understanding of the crucial roles performed by miRNAs in this process.