PsAAT3 Drives Ester Accumulation and Fruity Aroma Formation During Ripening in Chinese Plum (Prunus salicina) Through...

Fruit volatile organic compounds (VOCs) are key determinants of plum flavor quality, and esters contribute strongly to the fruity aroma of ripe fruit. However, the molecular basis of cultivar differences in ester formation during ripening has not been systematically clarified. Here, we characterized pulp VOC profiles across ripening in three Chinese plum (Prunus salicina) cultivars ('WeiWang' (WW), 'WeiDi' (WD), and 'KongLongDan' (KLD)) and integrated transcriptome analysis with weighted gene co-expression network analysis (WGCNA) to identify genes associated with ester accumulation. HS-SPME-GC-MS identified 38 VOCs, mainly esters, aldehydes, and alcohols, with 'WW' showing the highest total VOC abundance. During ripening, esters became the predominant volatile class in 'WW' and 'WD', in agreement with their fruity sensory characteristics, whereas 'KLD' maintained a more balanced composition of fruity and green-related volatiles. Transcriptomic analyses highlighted Prunus salicina alcohol acyltransferase 3 (PsAAT3) as the most abundant AAT transcript in pulp and strongly induced in 'WW'. Transient overexpression of PsAAT3 in the low-ester background increased butyl acetate and hexyl acetate by 4.8- and 2.2-fold, respectively. WGCNA further identified ester-associated modules and candidate transcription factors co-expressed with PsAAT3 (JA2L, HY5, NAC073, and PHL13). As a result, this study identifies PsAAT3 as a key determinant of high-ester aroma in Chinese plum and provide candidate targets for aroma improvement and flavor-oriented breeding.