Transcriptional profiling analysis of genic male sterile–fertile Capsicum annuum reveal candidate genes for pollen development and maturation by RNA-Seq technology

To identify genes involved in the pollen development and maturation, genome-wide transcriptional profiling of the flower buds from fertile and sterile plants of the genic male sterile–fertile line 114AB of Capsicum annuum was performed by the RNA-Seq approach. The results indicated that there were numerous changes in gene expression due to the gene mutation in sterile plants. A total of 668 differential expressed genes were identified. Among them, 562 were up-regulated and 106 were down-regulated genes in the fertile plants compared to those of the sterile plants, including 202 and 2 genes specifically accumulated in fertile and sterile plants, respectively. Hundreds of genes potentially involved in pollen development were identified from the genes specifically expressed in the fertile plants, including pollen coat protein, lipid binding protein, lipid transfer protein, pectin methylesterase, male sterility-related protein, anther-specific protein, pectate lyase gene and so forth. Subsequent analysis of expression patterns for a subset of these genes were verified by semi-quantitative RT-PCR and quantitative RT-PCR. Furthermore, the up-regulated genes were predicted to be associated with intracellular membrane-bounded organelle, cytoplasmic vesicle, oxidoreductase activity, metal ion binding, pollen wall assembly, pollen exine formation, starch and sucrose metabolism, and other processes through Gene ontology and KEGG enrichment analysis. Taken together, this study provides a list of candidate genes and their expression patterns for pollen development and maturation in pepper.