Integration of transcriptomics and metabolomics reveals the mechanism of aroma formation during apricot fruit development

• A total of 536 volatile metabolites spanning 16 categories were identified in apricot fruits, among which terpenes were the major volatile components. • The terpenoid and phenylpropanoid biosynthesis pathways are activated during aroma formation. • Fifteen key characteristic aroma components were identified. • Three transcription factors may be involved in the regulation of the volatile aroma components of these apricot fruits. Aroma is a crucial index of fruit quality. However, the regulatory mechanism of aroma formation during the ripening of apricot fruit has not been elucidated. Here, qualitative and quantitative studies of the metabolomes and transcriptomes of the Luntaibaixing and Suogejianali apricot cultivars, which have different aromas, were conducted at five developmental stages (S1-S5). A total of 536 volatile metabolites were detected; among them, the contents of (3Z,6Z)-nona-3,6-dienal, (Z)-non-6-enal, thiophene-2-ylmethanethiol and phenylmethanethiol significantly differed between the two cultivars, and we infer that these substances play decisive roles in aroma formation. Additionally, analysis of the differentially expressed genes (DEGs) among the different developmental stages of the two cultivars led to the identification of the key genes HCT-1, 4CL-1, TPS-1, IDI and HMGR-1 . We also found that the transcription factors MYB12, AP2/ERF32 and NAC15 might be involved in the synthesis of apricot aroma components. These results reveal the key metabolites and regulatory genes closely related to apricot fruit aroma, which provides a solid theoretical reference for the subsequent regulation of apricot fruit quality and cultivar selection.