Transcriptome sequencing and de novo analysis of a recessive genic male sterile line in cabbage (Brassica oleracea L. var. capitata)

Recessive genic male sterility (RGMS) is common in plants and has been widely applied as an effective and economic system for hybrid seed production in many crops. However, little is known regarding the molecular mechanisms of RGMS in cabbage (Brassica oleracea L. var. capitata) due to limited transcriptomic and genomic data. Comparative transcriptomic analyses were performed on the sterile (RGMS632-MS) and fertile plants (RGMS632-SF) of a RGMS line (RGMS632) using second-generation Illumina sequencing to identify critical genes and pathways associated with male sterility. A total of approximately 109 million sequencing reads was obtained using RNA-seq. Abundance analysis identified a total of 5107 unigenes that showed significant differences between the two kinds of plants. Among these, 1558 genes were upregulated while 3549 genes were downregulated by more than twofold in RGMS632-MS compared to RGMS632-SF. KEGG pathway enrichment analysis revealed changes in the transcript abundance of genes involved in the metabolism and signal transduction of various phytohormones. The majority of hormone signalling pathways were downregulated in RGMS632-MS. Furthermore, a set of potential candidate genes involved in the formation or abortion of pollen were investigated. These results increased our understanding of the molecular mechanisms and biological processes in RGMS plants.