Microbiology Laboratory, Department of Botany, University of North Bengal, Raja Rammohunpur, India.
Plant Biochemistry Laboratory, Department of Botany, University of North Bengal, Raja Rammohunpur, India.
Physiol Plant. 2021 Jun;172(2):1016-1029. doi: 10.1111/ppl.13338. Epub 2021 Feb 7.
Global increase in water scarcity is a serious problem for sustaining crop productivity. The lack of water causes the degeneration of the photosynthetic apparatus, an imbalance in key metabolic pathways, an increase in free radical generation as well as weakens the root architecture of plants. Drought is one of the major stresses that directly interferes with the osmotic status of plant cells. Abscisic acid (ABA) is known to be a key player in the modulation of drought responses in plants and involvement of both ABA-dependent and ABA-independent pathways have been observed during drought. Concomitantly, other phytohormones such as auxins, ethylene, gibberellins, cytokinins, jasmonic acid also confer drought tolerance and a crosstalk between different phytohormones and transcription factors at the molecular level exists. A number of drought-responsive genes and transcription factors have been utilized for producing transgenic plants for improved drought tolerance. Despite relentless efforts, biotechnological advances have failed to design completely stress tolerant plants until now. The root microbiome is the hidden treasure that possesses immense potential to revolutionize the strategies for inducing drought resistance in plants. Root microbiota consist of plant growth-promoting rhizobacteria, endophytes and mycorrhizas that form a consortium with the roots. Rhizospheric microbes are proliferous producers of phytohormones, mainly auxins, cytokinin, and ethylene as well as enzymes like the 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase) and metabolites like exopolysaccharides that help to induce systemic tolerance against drought. This review, therefore focuses on the major mechanisms of plant-microbe interactions under drought-stressed conditions and emphasizes the importance of drought-tolerant microbes for sustaining and improving the productivity of crop plants under stress.
全球水资源短缺的加剧对维持作物生产力是一个严重的问题。缺水会导致光合作用装置的退化、关键代谢途径的失衡、自由基生成的增加以及削弱植物的根系结构。干旱是直接干扰植物细胞渗透状态的主要胁迫之一。已知脱落酸（ABA）是植物中调节干旱响应的关键因子，在干旱过程中观察到 ABA 依赖和 ABA 非依赖途径的参与。同时，其他植物激素如生长素、乙烯、赤霉素、细胞分裂素、茉莉酸也赋予植物耐旱性，并且不同植物激素和转录因子之间在分子水平上存在串扰。许多干旱响应基因和转录因子已被用于生产转基因植物以提高耐旱性。尽管进行了不懈的努力，但生物技术的进步直到现在仍未能设计出完全耐受压力的植物。根际微生物组是一个隐藏的宝藏，拥有巨大的潜力可以彻底改变诱导植物抗旱性的策略。根际微生物群由植物生长促进根际细菌、内生菌和菌根组成，它们与根系形成联合体。根际微生物是植物激素的丰富生产者，主要是生长素、细胞分裂素和乙烯，以及 1-氨基环丙烷-1-羧酸脱氨酶（ACC 脱氨酶）等酶和外多糖等代谢物，有助于诱导植物对干旱的系统性耐受。因此，本综述重点讨论了植物-微生物相互作用在干旱胁迫条件下的主要机制，并强调了耐旱微生物对维持和提高胁迫下作物生产力的重要性。
