Wang Lanxiang, Liu Yue, Ni Haoran, Zuo Wenlong, Shi Haimei, Liao Weixin, Liu Hongbin, Chen Jiajia, Bai Yang, Yue Hong, Huang Ancheng, Friedman Jonathan, Si Tong, Liu Yinggao, Chen Moxian, Dai Lei
CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
National Key Laboratory of Wheat Improvement, College of Life Science, Shandong Agricultural University, Taian, China.
PLoS Biol. 2024 Nov 26;22(11):e3002921. doi: 10.1371/journal.pbio.3002921. eCollection 2024 Nov.
Plant-associated microbiota affect pant growth and development by regulating plant hormones homeostasis. Indole-3-acetic acid (IAA), a well-known plant hormone, can be produced by various plant-associated bacteria. However, the prevalence of bacteria with the capacity to degrade IAA in the rhizosphere has not been systematically studied. In this study, we analyzed the IAA degradation capabilities of bacterial isolates from the roots of Arabidopsis and rice. Using genomics analysis and in vitro assays, we found that 21 out of 183 taxonomically diverse bacterial isolates possess the ability to degrade IAA. Through comparative genomics and transcriptomic assays, we identified iac-like or iad-like operon in the genomes of these IAA degraders. Additionally, the putative regulator of the operon was found to be highly conserved among these strains through protein structure similarity analysis. Some of the IAA degraders could utilize IAA as their carbon and energy source. In planta, most of the IAA degrading strains mitigated Arabidopsis and rice seedling root growth inhibition (RGI) triggered by exogenous IAA. Moreover, RGI caused by complex synthetic bacterial community can be alleviated by introducing IAA degraders. Importantly, we observed increased colonization preference of IAA degraders from soil to root according to the frequency of the biomarker genes in metagenome-assembled genomes (MAGs) collected from different habitats, suggesting that there is a close association between IAA degraders and IAA producers. In summary, our findings further the understanding of the functional diversity and potential biological roles of plant-associated bacteria in host plant root morphogenesis.
与植物相关的微生物群通过调节植物激素稳态来影响植物的生长和发育。吲哚 - 3 - 乙酸（IAA）是一种著名的植物激素，可由多种与植物相关的细菌产生。然而，根际中具有降解IAA能力的细菌的普遍性尚未得到系统研究。在本研究中，我们分析了从拟南芥和水稻根部分离出的细菌的IAA降解能力。通过基因组学分析和体外试验，我们发现183种分类学上不同的细菌分离物中有21种具有降解IAA的能力。通过比较基因组学和转录组学试验，我们在这些IAA降解菌的基因组中鉴定出了iac样或iad样操纵子。此外，通过蛋白质结构相似性分析发现，这些菌株中操纵子的假定调节因子高度保守。一些IAA降解菌可以利用IAA作为其碳源和能源。在植物体内，大多数IAA降解菌株减轻了外源IAA引发的拟南芥和水稻幼苗根生长抑制（RGI）。此外，引入IAA降解菌可以缓解由复杂合成细菌群落引起的RGI。重要的是，根据从不同栖息地收集的宏基因组组装基因组（MAG）中生物标志物基因的频率，我们观察到IAA降解菌从土壤到根的定殖偏好增加，这表明IAA降解菌与IAA产生菌之间存在密切关联。总之，我们的研究结果进一步加深了对与植物相关细菌在宿主植物根形态发生中的功能多样性和潜在生物学作用的理解。
