Wang Yifeng, Wang Mingxia, Chen Yaonian, Hu Wenbin, Zhao Shuling
College of A & F Technology, Longnan Normal University, Longnan, Gansu, China.
Chengxian Walnut Technology Service Center, Longnan, Gansu, China.
Front Plant Sci. 2025 May 9;16:1582209. doi: 10.3389/fpls.2025.1582209. eCollection 2025.
Walnut () is an important woody plant worldwide, and endocarp color affects the economic value of walnut. During the postharvest processing and storage of walnut, the endocarp often undergoes browning. Browning has become a major obstacle to walnut storage, not only affecting the taste and flavor of walnuts but also reducing their nutritional quality and commercial value. In the present study, to elucidate the molecular mechanism of walnut endocarp browning, analyses of the ultrastructure, physiological characteristics, and transcriptomic and metabolomic data of walnut endocarps at different storage periods were performed. Integrated transcriptomic and metabolomic analysis showed that many differentially expressed genes (DEGs) and metabolites (DAMs) were involved in the pathways of flavonoid biosynthesis, amino acid biosynthesis, unsaturated fatty acid biosynthesis, phenylalanine metabolism, and oxidative phosphorylation. Among them, the expression levels of DEGs related to flavonoid metabolism and antioxidant activity had significant differences during their storage periods. In addition, the expression of stress-related transcription factors AP2/ERF, WRKY, bHLH, HSF, and MYB involved in the phenylpropanoid metabolic pathway was significantly upregulated during the browning process. This study comprehensively analyzed the causes of walnut endocarp browning, providing insights for studying the molecular mechanism of endocarp browning during storage and processing of walnuts and other fruits.
核桃（）是一种在全球范围内重要的木本植物，其果壳颜色影响核桃的经济价值。在核桃采后加工和贮藏过程中，果壳常发生褐变。褐变已成为核桃贮藏的主要障碍，不仅影响核桃的口感和风味，还降低其营养品质和商业价值。在本研究中，为阐明核桃果壳褐变的分子机制，对不同贮藏时期核桃果壳的超微结构、生理特性以及转录组和代谢组数据进行了分析。转录组和代谢组综合分析表明，许多差异表达基因（DEGs）和差异代谢物（DAMs）参与了类黄酮生物合成、氨基酸生物合成、不饱和脂肪酸生物合成、苯丙氨酸代谢和氧化磷酸化途径。其中，与类黄酮代谢和抗氧化活性相关的DEGs在贮藏期间表达水平有显著差异。此外，参与苯丙烷代谢途径的应激相关转录因子AP2/ERF、WRKY、bHLH、HSF和MYB的表达在褐变过程中显著上调。本研究全面分析了核桃果壳褐变的原因，为研究核桃及其他果实贮藏和加工过程中果壳褐变的分子机制提供了见解。
