DARWIN21, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia.
Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia.
Proc Natl Acad Sci U S A. 2021 Nov 16;118(46). doi: 10.1073/pnas.2107417118.
sp. SA187 is a root endophytic bacterium that maintains growth and yield of plants under abiotic stress conditions. In this work, we compared the metabolic wirings of Arabidopsis and SA187 in the free-living and endophytic interaction states. The interaction of SA187 with Arabidopsis induced massive changes in bacterial gene expression for chemotaxis, flagellar biosynthesis, quorum sensing, and biofilm formation. Besides modification of the bacterial carbon and energy metabolism, various nutrient and metabolite transporters and the entire sulfur pathway were up-regulated. Under salt stress, Arabidopsis resembled plants under sulfate starvation but not when colonized by SA187, which reprogramed the sulfur regulon of Arabidopsis. In accordance, salt hypersensitivity of multiple Arabidopsis sulfur metabolism mutants was partially or completely rescued by SA187 as much as by the addition of sulfate, L-cysteine, or L-methionine. Many components of the sulfur metabolism that are localized in the chloroplast were partially rescued by SA187. Finally, salt-induced accumulation of reactive oxygen species as well as the hypersensitivity of LSU mutants were suppressed by SA187. LSUs encode a central regulator linking sulfur metabolism to chloroplast superoxide dismutase activity. The coordinated regulation of the sulfur metabolic pathways in both the beneficial microorganism and the host plant is required for salt stress tolerance in Arabidopsis and might be a common mechanism utilized by different beneficial microbes to mitigate the harmful effects of different abiotic stresses on plants.
sp. SA187 是一种根内生细菌，能够在非生物胁迫条件下维持植物的生长和产量。在这项工作中，我们比较了自由生活和内生相互作用状态下拟南芥和 SA187 的代谢途径。SA187 与拟南芥的相互作用诱导了细菌趋化性、鞭毛生物合成、群体感应和生物膜形成的大量基因表达变化。除了细菌碳和能量代谢的修饰外，各种营养物质和代谢物转运体以及整个硫代谢途径都被上调。在盐胁迫下，拟南芥类似于硫酸盐饥饿的植物，但不同于被 SA187 定殖的植物，后者重新编程了拟南芥的硫调节子。相应地，SA187 对多个拟南芥硫代谢突变体的盐敏感性的部分或完全拯救作用与硫酸盐、L-半胱氨酸或 L-蛋氨酸的添加一样。定位于叶绿体的硫代谢的许多成分被 SA187 部分拯救。最后，盐诱导的活性氧积累以及 LSU 突变体的超敏性被 SA187 抑制。LSUs 编码一种将硫代谢与叶绿体超氧化物歧化酶活性联系起来的中央调节剂。有益微生物和宿主植物中硫代谢途径的协调调节是拟南芥耐盐性所必需的，可能是不同有益微生物利用的一种共同机制，以减轻不同非生物胁迫对植物的有害影响。
