Streptomyces alleviate abiotic stress in plant by producing pteridic acids

Soil microbiota can confer fitness advantages to plants and increase crop resilience to drought and other abiotic stressors. However, there is little evidence on the mechanisms correlating a microbial trait with plant abiotic stress tolerance. Here, we report that Streptomyces effectively alleviates the drought and salinity stress by producing spiroketal polyketide pteridic acid H (1) and its isomer F (2), both of which promote root growth in Arabidopsis at a concentration of 1.3 nM under abiotic stress. Pteridic acids induce stress response genes expression in salinity-stressed Arabidopsis seedlings. The bifunctional biosynthetic gene cluster of pteridic acids and antimicrobial elaiophylin is confirmed in vivo and mainly disseminated by vertical transmission which is geographically distributed in various environments. This discovery reveals a perspective for understanding plant-Streptomyces interactions and provides a promising approach for utilising beneficial Streptomyces and their secondary metabolites in agriculture to mitigate the detrimental effects of climate change.

土壤微生物群可为植物赋予生存适配优势，并提升作物对干旱及其他非生物胁迫的抗逆能力。然而，目前鲜有研究阐明微生物性状与植物非生物胁迫耐受性之间的关联机制。本研究发现，链霉菌（Streptomyces）可通过分泌螺环聚酮类化合物蝶啶酸H（1）及其同分异构体蝶啶酸F（2），有效缓解干旱与盐胁迫；在非生物胁迫条件下，二者以1.3纳摩尔的浓度即可促进拟南芥（Arabidopsis）的根系生长。蝶啶酸可诱导盐胁迫下拟南芥幼苗的胁迫响应基因表达。本研究在体内验证了蝶啶酸与抗菌性油霉素（elaiophylin）的双功能生物合成基因簇，该基因簇主要通过垂直传播进行扩散，且在各类地理环境中均有分布。本研究成果为解析植物-链霉菌互作机制提供了新视角，并为在农业生产中利用有益链霉菌及其次生代谢产物缓解气候变化带来的不利影响提供了极具潜力的解决方案。