Identification of differentially expressed miRNAs between male sterile and fertile floral buds in watermelon (Citrullus lanatus L.) via high-throughput sequencing

Many studies have shown that MicroRNAs are a type of endogenously expressed non-coding small RNAs, and they regulate target genes expression to influence anther or pollen development in various plants. However, their roles in watermelon anther or pollen development have not been rarely reported. To identify the types and expression patterns of miRNAs, small RNA sequencing was conducted using for watermelon male sterile buds MSB and fertile buds MFB. Differentially expressed miRNAs analysis showed that 36 miRNAs were discovered between MSB and MFB, and 7 DEMs were up-regulated while 29 DEMs were down-regulated. Target genes analysis showed that the 36 DEMs were predicted to target 577 genes, and these targets might participate in various biological processes, such as response to metal ion, floral organ development, stamen development, anther development, pollen maturation, and programmed cell death. Moreover, the pathway analysis indicated that these genes were mainly enriched in purine metabolism, starch and sucrose metabolism, RNA transport and other pathways. Besides, the 55 miRNA-target modules, including 3 known and 16 novel miRNAs with 30 target genes, might be related to watermelon anther or pollen development. Our findings point to some important miRNA-target modules related to watermelon pollen development, which will lay the foundation for later biological functional analysis.