Systematic identification and characterization of long non-coding RNAs involved in cytoplasmic male sterility in pepper (Capsicum annuum L.)

Long non-coding RNAs (lncRNAs) participate in many biological processes and play extremely important regulatory roles in animals and plants. However, little is known about lncRNAs and their functions in cytoplasmic male sterility (CMS) during the developmental process of floral buds in pepper. In the present study, we systematically identified lncRNAs in the pepper CMS line (9704A) and maintainer line (9704B) using high-throughput sequencing and bioinformatic analyses. A total of 10,655 putative lncRNAs were identified during the developmental process of floral buds, and 262, 298 and 905 differentially expressed lncRNAs (DELs) were obtained in three stages, respectively. Moreover, 1137 unique DELs were identified between 9704A and 9704B, and their cis and trans target protein-coding genes were predicted. We used Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses to decipher the potential functions of DELs. The cell and cellular process GO terms were significantly enriched, and KEGG pathway analysis showed enrichments in the pathways for starch and sucrose metabolism genes, pentose and glucuronate interconversions, all of which were highly associated with pollen development. Besides, a regulatory network about the lncRNAs and the protein-coding genes involved in the formation of CMS was constructed. Our findings laid a foundation for further studies on the function of lncRNAs in pollen development and provided valuable insights into the regulatory mechanism underlying CMS.