Integrated analysis of small RNA, transcriptome and degradome sequencing reveals that micro-RNAs regulate anther development in CMS cotton

Cytoplasmic male sterility (CMS) is an important phenotypic trait for heterosis utilization in cotton (Gosspium hirsutum L.). Micro-RNAs (miRNAs) play crucial roles in the pollen development of plants. To elucidate the roles of miRNA-target gene pairs in the CMS cotton line ganmian15A and its maintainer line ganmian15B, an integrated small RNA (sRNA), transcriptome, and degradome sequencing analysis of these lines at the pollen abortion stage was performed in the present research. A total of 339 known miRNAs and 961 conserved miRNAs were identified through high-throughput sequencing, among which 124 were differentially expressed between ganmian15A and ganmian15B. By comprehensive analysis of miRNA, transcriptome, and degradome sequencing, we identified 11 pairs of miRNAs/target genes at the pollen abortion stage. Among them, 9 miRNAs (4 novel and 5 known) were found for the first time to be associated with the occurrence of male sterility in cotton. The target genes of miRna-38 and miRna-23 were linked to cell wall development at the pollen stage. They may play an imperative role in CMS cotton by delaying the degradation of tapetal cells. Our findings revealed new insights into the genetic control of CMS occurrence, which will support the breeding of new sterile lines of cotton in the future.