Transcriptome and Metabolomics Integrated Analysis Reveals MdMYB94 Associated with Esters Biosynthesis in Apple (Malus x domestica)

Volatile esters are major aromas contributing to theorganolepticquality of apple fruit. However, the molecular mechanisms underlyingthe regulation of volatile ester biosynthesis in apple remain elusive.This study investigated the volatile profiles and transcriptomes of'Qinguan' (QG) apple fruit during development and/orpostharvest storage. Although the constitution of volatiles variedwidely between the peel and flesh, the volatile profiles of the peeland flesh of ripening QG fruit were dominated by volatile esters.WGCNA results suggested that 19 genes belonging to ester biosynthesispathways and 11 hub transcription factor genes potentially participatedin the biosynthesis and regulation of esters. To figure out key regulatorsof ester biosynthesis, correlation network analysis, dual-luciferaseassays, and yeast one-hybrid assay were conducted and suggested thatMdMYB94 trans-activated the MdAAT2 promoter and participatedin the regulation of ester biosynthesis. This study provides a frameworkfor understanding ester biosynthesis and regulation in apple.

Automated summary

Volatile esters play a significant role in the aroma of apple fruit, but the molecular mechanisms regulating their biosynthesis in apple remain unclear. This study investigated the volatile profiles and transcriptomes of 'Qinguan' apple fruit during development and postharvest storage. The results suggest that several genes and transcription factors are involved in the biosynthesis and regulation of esters. MdMYB94 was identified as a key regulator, as it trans-activated the MdAAT2 promoter and participated in the regulation of ester biosynthesis. This study provides insights into the biosynthesis and regulation of esters in apple.