School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
Environ Microbiol. 2022 Jun;24(6):2817-2836. doi: 10.1111/1462-2920.15743. Epub 2021 Sep 1.
Plant growth promotion by microbes is a cumulative phenomenon involving multiple traits, many of which are not explored yet. Hence, to unravel microbial mechanisms underlying growth promotion, we have analysed the genomes of two potential growth-promoting microbes, viz., Pseudomonas sp. CK-NBRI-02 (P2) and Bacillus marisflavi CK-NBRI-03 (P3) for the presence of plant-beneficial traits. Besides known traits, we found that microbes differ in their ability to metabolize methylglyoxal (MG), a ubiquitous cytotoxin regarded as general consequence of stress in plants. P2 exhibited greater tolerance to MG and possessed better ability to sustain plant growth under dicarbonyl stress. However, under salinity, only P3 showed a dose-dependent induction in MG detoxification activity in accordance with concomitant increase in MG levels, contributing to enhanced salt tolerance. Furthermore, salt-stressed transcriptomes of both the strains showed differences with respect to MG, ion and osmolyte homeostasis, with P3 being more responsive to stress. Importantly, application of either strain altered MG levels and subsequently MG detoxification machinery in Arabidopsis, probably to strengthen plant defence response and growth. We therefore, suggest a crucial role of microbial MG resistance in plant growth promotion and that it should be considered as a beneficial trait while screening microbes for stress mitigation in plants.
微生物促进植物生长是一个涉及多种特性的累积现象，其中许多特性尚未被探索。因此，为了揭示促进生长的微生物机制，我们分析了两个具有潜在生长促进作用的微生物（即假单胞菌 CK-NBRI-02（P2）和海洋芽孢杆菌 CK-NBRI-03（P3）的基因组，以寻找对植物有益的特性。除了已知的特性外，我们发现微生物在代谢甲基乙二醛（MG）的能力上存在差异，MG 是一种普遍存在的细胞毒素，被认为是植物应激的普遍后果。P2 对 MG 的耐受性更强，在二羰基应激下具有更好的维持植物生长的能力。然而，在盐胁迫下，只有 P3 表现出与 MG 水平升高相伴随的 MG 解毒活性的剂量依赖性诱导，从而增强了耐盐性。此外，两种菌株的盐胁迫转录组在 MG、离子和渗透调节剂稳态方面存在差异，P3 对胁迫的反应更为敏感。重要的是，两种菌株的应用都改变了拟南芥中的 MG 水平和随后的 MG 解毒机制，可能是为了加强植物的防御反应和生长。因此，我们认为微生物对 MG 的抗性在促进植物生长中起着至关重要的作用，在筛选微生物以减轻植物压力时，应该将其视为有益特性。
