Verticillium dahliae is a soil-borne, phytopathogenic fungus that causes Verticillium wilt in cotton. Salt tolerance of cotton plants suffering from Verticillium wilt was significantly improved, but the mechanism is unknown. In this study, we built a symbiont named Cotton≡VD by immersing cotton plant roots into Verticillium dahliae liquid for four days. This resulted in a strong interaction between hyphae and the cotton roots. Under NaCl treatment for 24 h, the Cotton≡VD displayed less leaf wilting and improved root growth compared with the control. Biochemical tests of SOD, POD and CAT showed significant overexpression in Cotton≡VD compared with CK. RNA-seq data analysis of Cotton≡VD indicated a novel ‘galactose metabolism pathway’ in the KEGG database, in which two key genes, GolS2 and RFS5, were significantly differentially expressed. Symbiotic metabolites inositol galactosyl could be transformed into raffinose to scavenge free radicals and participate in plant osmotic regulation to alleviate salt stress in Cotton≡VD. Functional analysis indicated that silencing of the target gene GhRFS (RFS5) led to a decrease of raffinose content and salt tolerance as compared with CK. Cotton≡VD can significantly improve cotton seedling salt tolerance through improving raffinose content, providing new insights into the salt tolerance mechanism and new salt-tolerant material in the future.

中文翻译：

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棉花≡大丽轮枝菌共生体观察到一种新的棉子糖生物学途径以遗传改善棉花的耐盐性

大丽轮枝菌是一种土壤传播的植物病原真菌，可导致棉花黄萎病。遭受黄萎病的棉花植株的耐盐性显着提高，但机制尚不清楚。在这项研究中，我们通过将棉花植物根部浸入大丽轮枝菌液体中四天，构建了一个名为 Cotton≡VD 的共生体。这导致菌丝和棉花根之间的强烈相互作用。在 NaCl 处理 24 h 下，与对照相比，Cotton≡VD 表现出较少的叶片萎蔫和改善根系生长。SOD、POD 和 CAT 的生化测试表明，与 CK 相比，Cotton≡VD 中的 SOD 显着过表达。Cotton≡VD 的 RNA-seq 数据分析表明 KEGG 数据库中有一个新的“半乳糖代谢途径”，其中两个关键基因GolS2和RFS5显着差异表达。共生代谢产物肌醇半乳糖基可转化为棉子糖以清除自由基并参与植物渗透调节以减轻棉花≡VD的盐胁迫。功能分析表明，与CK相比，靶基因GhRFS（RFS5）的沉默导致棉子糖含量和耐盐性降低。Cotton≡VD可以通过提高棉子糖含量显着提高棉花幼苗的耐盐性，为未来对耐盐机制和新的耐盐材料提供新的见解。