Microbial Technology Department, CSIR-Central Institute of Medicinal and Aromatic Plants, P.O. CIMAP-226015, Lucknow, India.
Department of Environmental Science, Babasaheb Bhimrao Ambedkar University, A Central University, Lucknow, India.
Physiol Plant. 2017 Dec;161(4):502-514. doi: 10.1111/ppl.12614. Epub 2017 Oct 10.
Abiotic stresses such as salt and drought represent adverse environmental conditions that significantly damage plant growth and agricultural productivity. In this study, the mechanism of the plant growth-promoting rhizo-bacteria (PGPR)-stimulated tolerance against abiotic stresses has been explored. Results suggest that PGPR strains, Arthrobacter protophormiae (SA3) and Dietzia natronolimnaea (STR1), can facilitate salt stress tolerance in wheat crop, while Bacillus subtilis (LDR2) can provide tolerance against drought stress in wheat. These PGPR strains enhance photosynthetic efficiency under salt and drought stress conditions. Moreover, all three PGPR strains increase indole-3-acetic acid (IAA) content of wheat under salt and drought stress conditions. The SA3 and LDR2 inoculations counteracted the increase of abscisic acid (ABA) and 1-aminocyclopropane-1-carboxylate (ACC) under both salt and drought stress conditions, whereas STR1 had no significant impact on the ABA and ACC content. The impact of PGPR inoculations on these physiological parameters were further confirmed by gene expression analysis as we observed enhanced levels of the TaCTR1 gene in SA3-, STR1- and LDR2-treated wheat seedlings as compared to uninoculated drought and salt stressed plants. PGPR inoculations enhanced expression of TaDREB2 gene encoding for a transcription factor, which has been shown to be important for improving the tolerance of plants to abiotic stress conditions. Our study suggest that PGPR confer abiotic stress tolerance in wheat by enhancing IAA content, reducing ABA/ACC content, modulating expression of a regulatory component (CTR1) of ethylene signaling pathway and DREB2 transcription factor.
非生物胁迫，如盐和干旱，代表着对植物生长和农业生产力有严重损害的不利环境条件。在本研究中，我们探索了植物促生根际细菌（PGPR）刺激对非生物胁迫耐受性的机制。结果表明，PGPR 菌株节杆菌（SA3）和地衣芽孢杆菌（STR1）可以促进小麦作物耐盐胁迫，而枯草芽孢杆菌（LDR2）可以使小麦耐旱。这些 PGPR 菌株在盐和干旱胁迫条件下提高了光合作用效率。此外，所有三种 PGPR 菌株都增加了盐和干旱胁迫条件下小麦的吲哚-3-乙酸（IAA）含量。SA3 和 LDR2 的接种可以抵消盐和干旱胁迫下 ABA 和 1-氨基环丙烷-1-羧酸（ACC）的增加，而 STR1 对 ABA 和 ACC 含量没有显著影响。PGPR 接种对这些生理参数的影响通过基因表达分析进一步得到证实，我们观察到，与未接种的干旱和盐胁迫植物相比，SA3、STR1 和 LDR2 处理的小麦幼苗中 TaCTR1 基因的水平显著提高。PGPR 接种增强了编码转录因子 TaDREB2 基因的表达，该转录因子对于提高植物对非生物胁迫条件的耐受性很重要。我们的研究表明，PGPR 通过增加 IAA 含量、降低 ABA/ACC 含量、调节乙烯信号途径的调控元件（CTR1）和 DREB2 转录因子的表达，赋予小麦非生物胁迫耐受性。
