Decoding comparative taste and nutrition regulation in Chinese cabbage via integrated metabolome and transcriptome analysis.

Chinese cabbage (Brassica rapa L. ssp. pekinensis) is a widely consumed leafy vegetable known for its various health-beneficial nutrients. Caixin (ET and JY) represent distinct cultivars of Chinese cabbage that exhibit differential consumer preference attributed to variations in taste and nutritional content, with ET being characterized as sweeter and more nutritionally superior compared to JY. However, limited research has been conducted to explore regulation of flavor and nutrition-related quality traits in Chinese cabbage. In this pioneer study, comprehensive trans-meta-analysis was used to compare the metabolic and molecular underpinnings behind unique taste and nutritional profiles of ET and JY. 8-Methylsulfonyloctyl glucosinolates and Uridine 5'-diphospho-D-glucose exhibited the highest correlation coefficient in Pearson meta-meta-association, which modulate flavor and nutrition processes. While DAMs primarily featured L-Homomethionine, saccharic acid, 1,6-Di-O-caffeoyl-ß-D-glucose, and Rutin, with notable variations in expression between ET and JY. Conspicuously, DEGs encoding structural enzymes i.e. Glucosinolates (MAM, CYP, UGT), flavonoids (CHS, CHI, F3H) and sucrose (SPS, SPP, SUS) synthases were identified as key players in nutrient and flavor production. Multi-omics conjoint analysis revealed that saccharides, amino acids, ascorbates, flavonoids, organic acids and vitamins were positively correlated with taste and nutrition, and were found to be overexpressed in ET. While aliphatic glucosinolates were abundant in JY compared to ET, they might play a critical role in regulating quality traits. Besides, HPLC and RT-qPCR corroborated multi-omics data reliability. These findings offer novel insights into the mechanisms governing the regulation of taste and nutritional levels in Chinese cabbage.

Comparing the differences in quality profiles and antioxidant activity in seven pumpkin cultivars (Cucurbita moschata and Cucurbita maxima) at harvest and during postharvest storage.

Pumpkin, nutritious vegetable, is renowned for its extended shelf life. In this study, seven pumpkin cultivars from Cucurbita moschata and Cucurbita maxima were comparatively characterized for 25 physiochemical quality factors, starch granule structures, antioxidant activity, and correlations at 0-60 days of postharvest (dop). The findings revealed that sucrose and carotenoid contents increased in C. moschata, while they initially increased and then decreased in C. maxima. Additionally, acidity, primarily driven by malic acid, decreased in C. maxima but increased in C. maxima. The starch content of C. moschata and C. maxima reached its maximum value at 30 dop and 20 dop, respectively. The DPPH radical scavenging activity correlated with the carotenoid content in both pumpkin species. Conclusively, C. moschata demonstrated improved nutritional and quality at 20-30 dop, while C. maxima exhibited higher commercial suitability at 10-20 dop. The findings suggested that pumpkin storage was crucial for quality improvement.

Transcriptomic analysis reveals the molecular basis of photoperiod-regulated sex differentiation in tropical pumpkins (Cucurbita moschata Duch.).

BACKGROUND: Photoperiod, or the length of the day, has a significant impact on the flowering and sex differentiation of photoperiod-sensitive crops. The "miben" pumpkin (the main type of Cucurbita moschata Duch.) is well-known for its high yield and strong disease resistance. However, its cultivation has been limited due to its sensitivity to photoperiod. This sensitivity imposes challenges on its widespread cultivation and may result in suboptimal yields in regions with specific daylength conditions. As a consequence, efforts are being made to explore potential strategies or breeding techniques to enhance its adaptability to a broader range of photoperiods, thus unlocking its full cultivation potential and further promoting its valuable traits in agriculture. RESULTS: This study aimed to identify photoperiod-insensitive germplasm exhibiting no difference in sex differentiation under different day-length conditions. The investigation involved a phenotypic analysis of photoperiod-sensitive (PPS) and photoperiod-insensitive (PPIS) pumpkin materials exposed to different day lengths, including long days (LDs) and short days (SDs). The results revealed that female flower differentiation was significantly inhibited in PPS_LD, while no differences were observed in the other three groups (PPS_SD, PPIS_LD, and PPIS_SD). Transcriptome analysis was carried out for these four groups to explore the main-effect genes of sex differentiation responsive to photoperiod. The main-effect gene subclusters were identified based on the principal component and hierarchical cluster analyses. Further, functional annotations and enrichment analysis revealed significant upregulation of photoreceptors (CmCRY1, F-box/kelch-repeat protein), circadian rhythm-related genes (CmGI, CmPRR9, etc.), and CONSTANS (CO) in PPS_LD. Conversely, a significant downregulation was observed in most Nuclear Factor Y (NF-Y) transcription factors. Regarding the gibberellic acid (GA) signal transduction pathway, positive regulators of GA signaling (CmSCL3, CmSCL13, and so forth) displayed higher expression levels, while the negative regulators of GA signaling, CmGAI, exhibited lower expression levels in PPS_LD. Notably, this effect was not observed in the synthetic pathway genes. Furthermore, genes associated with ethylene synthesis and signal transduction (CmACO3, CmACO1, CmERF118, CmERF118-like1,2, CmWIN1-like, and CmRAP2-7-like) showed significant downregulation. CONCLUSIONS: This study offered a crucial theoretical and genetic basis for understanding how photoperiod influences the mechanism of female flower differentiation in pumpkins.