Cyclocarya paliurus is a highly valued and multiple function tree species, and especially its leaves are enriched in diverse secondary metabolites with healthy function. Flavonoids as a kind of secondary metabolites are not only an important part of plant defense system against environmental stresses but also commercial pharmaceutical substances. To meet the leaf production for value-added product development, coastal saline would be a potential land resources for developing C. paliurus plantations, whereas there is limited knowledge on the regulatory mechanisms of flavonoid biosynthesis under salt stress in C. paliurus. Here, we conducted an integrated transcriptomics and metabolomics analysis of C. paliurus under different salt treatments in the short (T₁, treatment lasted for 15 days) and long (T₂, treatment lasted for 30 days) term. Generally, salt treatments led to increased total flavonoid content in C. paliurus leaves, which increased gradually along with salt stress concentration. For instance, after seedlings were salt-treated with LS (0.15 %), MS (0.30 %) and HS (0.45 %), the total flavonoid content was increased by 26.23 %, 57.54 %, and 74.87 %, respectively, compared with the control (0.00 %, m/v) at T_1. Correspondingly, significant enrichment of differentially expressed genes and metabolites was observed in the flavonoid biosynthesis pathways. Weighted gene co-expression network analysis (WGCNA) identified several key genes regulating the responses to salt stress, such as genes encoding phenylalanine ammonia lyase (PAL), chalcone synthase (CHS) and flavonol synthase (FLS). In addition, fifteen transcription factors (TFs) were found to regulate flavonoid biosynthesis by activating or repressing the expression of multiple structural genes in C. paliurus leaves during salt stress. These findings provide insight into the salt stress associated transcriptional regulation, and would drive progress in genetic improvement and plantation development of C. paliurus.

青钱柳是一种价值很高的多功能树种，特别是它的叶子富含多种具有健康功能的次生代谢产物。黄酮类化合物作为一种次生代谢产物，不仅是植物抵御环境胁迫的重要组成部分，也是商业药物。为了满足叶片生产的增值产品开发，沿海盐碱地将成为开发C. paliurus人工林的潜在土地资源，而对C. paliurus盐胁迫下黄酮类生物合成的调控机制知之甚少。在这里，我们对C. paliurus进行了综合转录组学和代谢组学分析短（T ₁，处理持续15天）和长期（T ₂，处理持续30天）不同盐处理。一般而言，盐处理导致C.paliurus叶片总黄酮含量增加，并随着盐胁迫浓度的增加而逐渐增加。例如，幼苗经 LS（0.15%）、MS（0.30%）和 HS（0.45%）盐处理后，总黄酮含量分别增加了 26.23%、57.54% 和 74.87%。对照 (0.00 %, m/v) 在 T _1。相应地，在类黄酮生物合成途径中观察到差异表达的基因和代谢物的显着富集。加权基因共表达网络分析 (WGCNA) 确定了几个调节盐胁迫反应的关键基因，例如编码苯丙氨酸解氨酶 (PAL)、查尔酮合酶 (CHS) 和黄酮醇合酶 (FLS) 的基因。此外，发现十五种转录因子 (TF) 通过在盐胁迫期间激活或抑制C.paliurus叶片中多个结构基因的表达来调节类黄酮生物合成。这些发现提供了对盐胁迫相关转录调控的深入了解，并将推动C. paliurus 的遗传改良和种植园发展的进展。