Comparative transcriptome analyses of fruit development and ripening in two Chinese bayberry cultivars

Chinese bayberry is an important subtropical fruits crop in China and the fruit characteristics such as drop rate were divergent between the different cultivars, however, the underlying mechanism has not been fully understood. Here, a comparative transcriptome analyses based on RNA-Seq and bioinformatic analysis have been performed on the two cultivars, providing a foundation for understanding the molecular mechanisms during the fruit development and ripening process. We observed that expressed genes in several clusters were highly associated with several developmental processes, for example, salicylic acid (SA) mediated signaling pathways and jasmonic acid mediated signaling pathways. We uncovered several key TFs in sugar-metabolism signaling pathway and hormone-mediated signaling pathways, including MYB, basic helix-loop-helix (bHLH), ethylene responsive factor (ERF), MADS-Box, WRKY, basic leucine zipper (bZIP) was detected. Heterologous overexpression of MrMYB6 in Arabidopsis indicated their effects on enhancing synthesis of SA, seed germination and leaf growth. Whereas, the RNAi of MrMYB6 inhibited plant growth and synthesis of SA. We combined gene regulatory network and DAP-seq approaches. MrMYB6 and its target, a salicylic acid 1 (SA1), were identified as an important regulatory module in the fruits development. These data provide an invaluable genetic resource for molecular breeding and postharvest storage of Chinese bayberry.