Identification and profiling of microRNAs and differentially expressed genes during anther development between a genetic male-sterile mutant and its wildtype cotton via high-throughput RNA sequencing

Genetic male sterility (GMS) facilitates hybrid seed production in crops including cotton (Gossypium hirsutum). However, the genetic and molecular mechanisms specifically involved in this developmental process are poorly understood. In this study, small RNA sequencing, degradome sequencing, and transcriptome sequencing were performed to analyze miRNAs and their target genes during anther development in a GMS mutant (‘Dong A’) and its fertile wildtype (WT). A total of 80 known and 220 novel miRNAs were identified, 71 of which showed differential expressions during anther development. A further degradome sequencing revealed a total of 117 candidate target genes cleaved by 16 known and 36 novel miRNAs. Based on RNA-seq, 24, 11, and 21 predicted target genes showed expression correlations with the corresponding miRNAs at the meiosis, tetrad and uninucleate stages, respectively. In addition, a large number of differentially expressed genes were identified, most of which were involved in sucrose and starch metabolism, carbohydrate metabolism, and plant hormone signal transduction based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The results of our study provide valuable information for further functional investigations of the important miRNAs and target genes involved in genetic male sterility and advance our understanding of miRNA regulatory functions during cotton anther development.