Persimmon (Diospyros kaki) fruit have significant variation between pollination-constant non-astringent (PCNA) and pollination-constant astringent (PCA) persimmons. The astringency type affects not only the soluble tannin concentration but also the accumulation of individual sugars. Thus, we comprehensively investigate the gene expression and metabolite profiles of individual sugars to resolve the formation of flavor differences in PCNA and PCA persimmon fruit. The results showed that soluble sugar, starch content, sucrose synthase, and sucrose invertase were significantly different between PCNA and PCA persimmon fruit. The sucrose and starch metabolism pathway was considerably enriched, and six sugar metabolites involving this pathway were significantly differentially accumulated. In addition, the expression patterns of diferentially expressed genes (such as bglX, eglC, Cel, TPS, SUS, and TREH genes) were significantly correlated with the content of deferentially accumulated metabolites (such as starch, sucrose, and trehalose) in the sucrose and starch metabolism pathway. These results indicated that the sucrose and starch metabolism pathway maintained a central position of sugar metabolism between PCNA and PCA persimmon fruit. Our results provide a theoretical basis for exploring functional genes related to sugar metabolism and provide useful resources for future studies on the flavor differences between PCNA and PCA persimmon fruit.

Persimmon (Diospyros kaki Thunb.) is an economically important tree with a long history of cultivation in China. So far, a total of approximately 1000 varieties have been found in China. To systematically evaluate the diversity of persimmon fruit quality, 22 quality measures of appearance, intrinsic, and sensory quality were evaluated using 61 typical persimmon fruit. According to the findings, the coefficient of variation (CV) of 15 appearance and intrinsic quality index values ranged from 13.81% (fruit shape index) to 165.80% (firmness), and the CV values of 7 intrinsic quality attributes were all higher than 50%, with the CV of total polyphenols and ironic soluble pectin contents (ISP) being as high as 159.82% and 143.80%, respectively. These findings showed that several persimmon germplasm resources had a highly diverse range of fruit quality, wide variation, and distribution. Insoluble tannin and soluble sugar were shown to have a substantial positive correlation with the sensory flavor indexes (p < 0.05), indicating their significance in influencing the flavor quality of persimmon fruit. Cluster analysis was performed utilizing 15 indexes of appearance, intrinsic quality, and 7 indexes of sensory quality. The samples were divided into two groups: group I consisted of 52 pollination−constant and astringent (PCA) and 1 pollination−-variant astringent (PVA) persimmon resources, and group II consisted of 6 pollination−constant non−astringent (PCNA) and 2 pollination−variant non−astringent (PVNA) persimmon resources. The results were consistent with the classification based on the mode of astringency loss, indicating that there was a significant difference in the quality of astringent and non−astringent persimmon fruit. This study provides theoretical references for the development and application of persimmon germplasm resources.

The characteristic green-note aroma of Chinese plum (Prunus salicina) is largely defined by C6 aldehydes and alcohols synthesized through the fatty acid pathway involving lipoxygenase (LOX), hydroperoxide lyase (HPL), and alcohol dehydrogenase (ADH). However, the LOX/HPL/ADH gene families and their potential contributions to C6 volatile formation remain poorly characterized in Chinese plum. Here, we integrated genome-wide identification with cultivar-level volatile profiling and RT–qPCR expression analyses to link candidate genes with C6 volatile accumulation. We identified 8 PsLOX, 3 PsHPL, and 13 PsADH genes and classified them into 2, 1, and 3 subfamilies, respectively. Conserved motifs/domains were shared within each family, whereas gene-structure variation suggested functional divergence; segmental duplication was the main driver of family expansion. To explore their functional relevance to aroma biosynthesis, five major C6 aldehydes and alcohols were analyzed in ten cultivars using solid-phase microextraction/gas chromatography-mass spectrometry (SPME/GC–MS), revealing substantial diversity in green-note composition. Combined with reverse transcription quantitative polymerase chain reaction (qRT–PCR) expression profiling, low PsADH2.7 expression was associated with high hexanal content, whereas elevated PsLOX5 and PsADH2.2 expression corresponded to increased 1-hexanol accumulation. High 2-ethyl-1-hexanol levels were linked to increased PsLOX4.1 and PsHPL1.3 but decreased PsADH1.2 expression. In addition, (Z)-3-hexen-1-ol abundance showed strong positive correlations with PsLOX3.1, PsHPL1.2, and PsADH2.6 expression. This integrated genomic and expression–metabolite analysis highlights candidate genes potentially involved in C6 aldehyde/alcohol biosynthesis underlying the green-note aroma of Chinese plum and provides genetic targets for aroma-oriented breeding.

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.

Anthocyanins are major determinants of both the color and nutritional quality of fruit. Their accumulation in plant tissues depends on biosynthesis as well as efficient transport into the vacuole, a process in which glutathione S-transferases (GSTs) are believed to play an important role. Through genome-wide identification and analysis, this study identified 39 Chinese plum (Prunus salicina) glutathione S-transferase (PsGST) genes. Phylogenetic analysis grouped these PsGST genes into seven subfamilies. Dispersed duplication appeared to be the main driver of family expansion, and the duplicated genes appear to have largely evolved under purifying selection. The cultivar ‘Fengweimeigui’ (FWMG), with purple peel and red pulp, and the cultivar ‘Fengweihuanghou’ (FWHH), with yellow peel and yellow pulp, were used as contrasting materials because of their distinct anthocyanin pigmentation. We then profiled anthocyanin accumulation and the expression patterns of all PsGST genes across fruit development using quantitative real-time PCR (qRT-PCR). PsGSTF8 was identified as a candidate gene, and its expression patterns in both peel and pulp were consistent with anthocyanin accumulation, with higher relative transcript levels in the deeply colored cultivar ‘FWMG’ and undetectable expression in ‘FWHH’. The transient overexpression of PsGSTF8 in Chinese plum fruit promoted anthocyanin accumulation, and the complementation of the Arabidopsis thaliana transparent testa 19 (tt19) mutant further supported the potential role of PsGSTF8 in anthocyanin accumulation and GST-mediated transport. These results provide new clues for understanding potential GST-mediated anthocyanin transport and accumulation and offer a basis for the further investigation of the molecular mechanisms underlying fruit coloration in Chinese plum.