Song Xin, Wang Tingting, Zhao Peng, Fan Yanjie, He Ligang, Zhang Yu, Wang Zhijing, Ma Xiaofang, Xiao Cui, Jiang Yingchun, Song Fang, Wu Liming
Hubei Key Laboratory of Germplasm Innovation and Utilization of Fruit Trees, Institute of Fruit and Tea, Hubei Academy of Agricultural Science, Wuhan 430064, China.
National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
Plants (Basel). 2025 Sep 3;14(17):2751. doi: 10.3390/plants14172751.
Flavor formation in citrus fruit is governed by complex and dynamic changes in primary and secondary metabolism during development and ripening. Here, we integrated metabolomic, hormonal, and transcriptomic analyses to elucidate the regulatory landscape underlying soluble sugar and organic acid metabolism in 'Kiyomi' citrus fruit. A total of 1679 metabolites were identified, revealing stage-specific reprogramming of metabolic pathways, including a sharp decline in citric acid after 90 days after flowering (DAF) and peak accumulation of sucrose at 180 DAF. Hormonal profiling showed that abscisic acid (ABA) progressively accumulated from 120 to 210 DAF, while 1-aminocyclopropane-1-carboxylic acid (ACC) peaked at 120 DAF and declined thereafter, suggesting distinct and temporally coordinated roles in ripening regulation. Transcriptomic profiling uncovered widespread temporal shifts in gene expression, with the most pronounced changes occurring between 180 and 210 DAF. Co-expression network analysis identified gene modules associated with sugar and acid accumulation, and highlighted transcription factors from the ERF, MYB, NAC, and HSF families as candidate regulators of ripening-related metabolic transitions. These findings provide a comprehensive framework for understanding the coordinated molecular and metabolic programs underlying flavor development in non-climacteric citrus fruit and offer candidate genes for the genetic improvement of fruit quality.
柑橘果实中的风味形成受发育和成熟过程中初级和次级代谢复杂且动态变化的调控。在此，我们整合了代谢组学、激素组学和转录组学分析，以阐明‘清见’柑橘果实中可溶性糖和有机酸代谢的调控格局。共鉴定出1679种代谢物，揭示了代谢途径的阶段特异性重编程，包括花后90天（DAF）后柠檬酸急剧下降以及180 DAF时蔗糖积累达到峰值。激素分析表明，脱落酸（ABA）在120至210 DAF期间逐渐积累，而1-氨基环丙烷-1-羧酸（ACC）在120 DAF时达到峰值，随后下降，这表明它们在成熟调控中具有不同且时间上协调的作用。转录组分析揭示了基因表达广泛的时间变化，最显著的变化发生在180至210 DAF之间。共表达网络分析确定了与糖和酸积累相关的基因模块，并突出了来自ERF、MYB、NAC和HSF家族的转录因子作为成熟相关代谢转变的候选调节因子。这些发现为理解非跃变型柑橘果实风味发育背后的分子和代谢程序协调提供了一个全面的框架，并为果实品质的遗传改良提供了候选基因。
