Comparative Transcriptome Analysis Reveals the Molecular Mechanisms Underlying Male Sterility in Autotetraploid Watermelon

Plant male sterility not only has important theoretical value in the study of plant development, but also has important application value in the utilization of heterosis in crops and fruits. However, the molecular mechanism of male sterility in watermelon, especially in artificially created autotetraploid watermelon, is still unclear. In the present study, we performed comparative transcriptome analysis between two normal fertile autotetraploid watermelon W59 and N14 and a male sterile autotetraploid watermelon N14-MS. A total of 1,045 differentially expressed genes (DEGs) related to the male sterility were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment of the DGEs showed that pathways of lipid metabolism and flavonoid biosynthesis were significantly enriched. Moreover, a number of DEGs related to male sterility were identified, including the CER1, FAR, LOX2S, HPL, OPR, CHS and F3H gene. Also, DEGs directly regulate anther cuticle development and pollen wall development were detected, such as the BAHD acyltransferase gene, GDSL esterase/lipase gene, and jasmonic acid-amino synthetase. Furthermore, a number of differentially expressed transcription factors including the MYBs, WRKYs, MADS, and bHLHs were identified. Our research provides a basis for further studies of molecular mechanism of male sterility in watermelon and related cucurbit plants.