Institute of Molecular Biology and Biotechnology, Bahauddin Zakariya University, 60800 Multan, Pakistan.
National Institute for Biotechnology and Genetic Engineering (NIBGE), P.O. Box 577, Jhang Road, Faisalabad, Pakistan.
Microbiol Res. 2020 Sep;238:126486. doi: 10.1016/j.micres.2020.126486. Epub 2020 May 1.
Agricultural manipulation of potentially beneficial rhizosphere microbes is increasing rapidly due to their multi-functional plant-protective and growth related benefits. Plant growth promoting rhizobacteria (PGPR) are mostly non-pathogenic microbes which exert direct benefits on plants while there are rhizosphere bacteria which indirectly help plant by ameliorating the biotic and/or abiotic stress or induction of defense response in plant. Regulation of these direct or indirect effect takes place via highly specialized communication system induced at multiple levels of interaction i.e., inter-species, intra-species, and inter-kingdom. Studies have provided insights into the functioning of signaling molecules involved in communication and induction of defense responses. Activation of host immune responses upon bacterial infection or rhizobacteria perception requires comprehensive and precise gene expression reprogramming and communication between hosts and microbes. Majority of studies have focused on signaling of host pattern recognition receptors (PRR) and nod-like receptor (NLR) and microbial effector proteins under mining the role of other components such as mitogen activated protein kinase (MAPK), microRNA, histone deacytylases. The later ones are important regulators of gene expression reprogramming in plant immune responses, pathogen virulence and communications in plant-microbe interactions. During the past decade, inoculation of PGPR has emerged as potential strategy to induce biotic and abiotic stress tolerance in plants; hence, it is imperative to expose the basis of these interactions. This review discusses microbes and plants derived signaling molecules for their communication, regulatory and signaling networks of PGPR and their different products that are involved in inducing resistance and tolerance in plants against environmental stresses and the effect of defense signaling on root microbiome. We expect that it will lead to the development and exploitation of beneficial microbes as source of crop biofertilizers in climate changing scenario enabling more sustainable agriculture.
由于具有多功能的植物保护和生长相关益处，农业对潜在有益的根际微生物的操纵正在迅速增加。植物促生根际细菌（PGPR）大多是非病原微生物，它们直接对植物有益，而有些根际细菌则通过改善生物和/或非生物胁迫或诱导植物防御反应来间接帮助植物。这些直接或间接效应的调节是通过在多个相互作用水平（即种间、种内和种间）诱导的高度专业化的通信系统来进行的。研究已经深入了解了参与通信和诱导防御反应的信号分子的功能。细菌感染或根际细菌感知后宿主免疫反应的激活需要宿主和微生物之间的全面和精确的基因表达重编程和通信。大多数研究都集中在宿主模式识别受体（PRR）和核苷酸结合寡聚化结构域样受体（NLR）的信号以及挖掘其他成分（如丝裂原活化蛋白激酶（MAPK）、microRNA、组蛋白脱乙酰酶）的微生物效应蛋白的信号。后一类是植物免疫反应、病原体毒力和植物-微生物相互作用中基因表达重编程的重要调节剂。在过去的十年中，PGPR 的接种已成为诱导植物生物和非生物胁迫耐受性的潜在策略；因此，揭示这些相互作用的基础至关重要。本文综述了微生物和植物衍生的信号分子在其通信、PGPR 的调控和信号网络及其不同产物在诱导植物对环境胁迫的抗性和耐受性中的作用，以及防御信号对根际微生物组的影响。我们期望这将导致有益微生物的开发和利用，作为气候变化情景下作物生物肥料的来源，使农业更具可持续性。
