植物响应盐碱胁迫的生理分子和微生物学机制

Physiological, molecular, and microbiological mechanisms of plant response to saline-alkaline stress

关键词:  盐碱胁迫, 生物调节, 植物生长促进微生物(PGPM), 促生作用, 根际微生物

Key words:  saline-alkaline stress, biological regulation, plant growth-promoting microorganisms(PGPM), growth-promoting effect, rhizosphere microbial community

摘要:

土壤盐碱化是影响土壤环境和农业生产的重要限制因素,会对植物的生长代谢活动产生不利影响。植物在长期进化中发展出复杂的机制以应对盐碱胁迫,例如,改变形态结构、激活抗氧化防御系统、调节渗透平衡、维持细胞离子稳态、调控植物激素水平、稳定细胞内pH值以确保正常生化反应。此外,植物还可通过调控基因、转录因子的表达,激活信号转导通路以响应盐碱胁迫。同时,植物根系分泌物作为化学信号,在根际环境中选择性招募特定有益微生物,重塑根际微生物群落的多样性、组成、结构及功能特性,构建出适应盐碱胁迫的根际环境。植物生长促进微生物(plant growth-promoting microorganisms,PGPM)因与植物的共生关系被认为是植物的第二基因组,可通过多种协同机制增强植物耐盐碱性。主要包括主要包括调节植物激素水平、控制渗透平衡、增强抗氧化防御系统、维持离子平衡、促进营养吸收、调节代谢途径,从而提高植物的耐盐碱性。通过富集有益微生物以促进宿主植物生长,并增强其抗逆性。该文系统综述了植物应对盐碱胁迫的形态学、生理学、分子学及根际微生物学机制,重点阐明了根际微生物群在维持盐碱环境下植物生命活动中的关键作用,为盐碱地区可持续农业发展与生态修复提供了坚实的科学基础。

Abstract:

Soil salinization is a significant limiting factor affecting soil environment and agricultural production, adversely impacting plant growth and metabolic activities. Through long-term evolutionary adaptation, plants have developed complex mechanisms to counteract saline-alkaline stress via intrinsic metabolic regulation. For instance, they alter the morphological structure of roots and leaves to increase plant water uptake and transpiration, activate antioxidant defense systems(enzymes and compounds)to scavenge stress-induced reactive oxygen species(ROS), accumulate various osmotic substances(proline, soluble sugar, soluble protein, and polyols)to regulate osmotic balance, maintain cellular ion homeostasis, modulate endogenous plant hormone levels(abscisic acid, gibberellic acid, auxin, and cytokinin)to coordinate growth and stress responses, and stabilize intracellular pH(HCO₃^-/CO₃^2- stress)to ensure normal biochemical reactions. Moreover, plants respond to saline-alkaline stress by regulating the transcription of stress-responsive genes and transcription factors, coupled with triggering signal transduction pathways. Meanwhile, plant root exudates function as chemical signals to selectively recruit specific beneficial microorganisms in the rhizosphere. This recruitment process reshapes the diversity, composition, structure, and functional characteristics of the rhizosphere environment, constructing a rhizosphere microhabitat adaptive to saline-alkaline stress. Plant growth-promoting microorganisms(PGPM), recognized as the “second genome” of plants owing to their close symbiotic relationship with plants, enhance plant saline-alkaline tolerance through various synergistic mechanisms. These primarily include regulating plant hormone levels, controlling osmotic balance, enhancing the antioxidant defense system, maintaining ion balance, promoting nutrient absorption, and regulating metabolic pathways, thereby improving the plant's tolerance to salinity and alkalinity. PGPM can influence the assembly of the rhizosphere microbial community, promoting host plant growth and enhancing its stress tolerance by enriching beneficial microorganisms. This maintains their ability to promote plant growth and mitigate stress effects. This review systematically summarizes the morphological, physiological, molecular, and rhizosphere microbiological mechanisms by which plants respond to saline-alkaline stress. It highlights the pivotal role of PGPM in sustaining plant life under saline-alkaline conditions, provides a robust scientific foundation for sustainable agricultural development and ecological restoration in saline-alkaline regions.