Characterization and utilization of multi-trait plant growth promoting rhizobacteria from arid soils of western Rajasthan for enhancing drought resilience in an arid legume

In the study, plant growth promoting rhizobacteria (PGPR) indigenous to arid western Rajasthan were isolated and screened for plant growth promoting (PGP) capabilities. Ten isolates showing multiple PGP activities were identified as <i>Pseudomonas</i> sp. G6-3, <i>Staphylococcus</i> sp. G6-4, <i>Bacillus badius</i> G8-6, <i>Agrobacterium</i> sp. G8-7, <i>Bacillus pseudomycoides</i> G10-1, <i>Staphylococcus capitis</i> subsp. <i>capitis</i> G11-4, <i>Bacillus paralicheniformis</i> G11-5, <i>Bacillus subtilis</i> G12-3, <i>Stenotrophomonas pavanii</i> G12-4, and <i>Solibacillus isronensis</i> G21-9. Physiological profiling of these isolates demonstrated them to be tolerant to drought (25% PEG-6000), high temperature (40 °C), alkalinity (pH 10.0), and salinity (4.5% NaCl). These PGPR significantly improved clusterbean seedling characteristics in moisture stress-induced hydroponic flask cultures and pots. PGPR inoculation of clusterbean in drought-induced pots significantly enhanced the plant dry weight by 15–33%, plant water potential by 5–8%, and the relative water content of leaves by 4–16%. There was also a significant reduction in the levels of anti-oxidant enzymes and proline in plant tissues under drought conditions, which indicated lower levels of stress experienced by the treated plants. These were translated into yield enhancements by 13–15% under rainfed conditions. The study demonstrates the ability of stress tolerant PGPR from arid western Rajasthan in enhancing drought resilience of arid legumes besides promoting their growth, and their potential utility in sustainable arid agriculture systems.

本研究从干旱的拉贾斯坦邦西部本土分离得到植物促生根际菌（plant growth promoting rhizobacteria, PGPR），并针对其植物促生（plant growth promoting, PGP）能力开展筛选。最终获得10株具备多重PGP活性的分离株，经鉴定分别为假单胞菌属（Pseudomonas）sp. G6-3、葡萄球菌属（Staphylococcus）sp. G6-4、趋边芽孢杆菌（Bacillus badius）G8-6、农杆菌属（Agrobacterium）sp. G8-7、假类芽孢杆菌（Bacillus pseudomycoides）G10-1、头状葡萄球菌头状亚种（Staphylococcus capitis subsp. capitis）G11-4、副地衣芽孢杆菌（Bacillus paralicheniformis）G11-5、枯草芽孢杆菌（Bacillus subtilis）G12-3、帕瓦尼窄食单胞菌（Stenotrophomonas pavanii）G12-4以及以色列溶杆菌（Solibacillus isronensis）G21-9。生理特性分析表明，上述分离株可耐受干旱胁迫（25% PEG-6000）、高温（40℃）、碱性环境（pH 10.0）与高盐胁迫（4.5% NaCl）。在水分胁迫诱导的水培瓶培体系与盆栽体系中，这些PGPR可显著改善瓜尔豆幼苗的生长性状。对干旱胁迫盆栽中的瓜尔豆接种PGPR，能使植株干重提升15%~33%、植株水势提升5%~8%，叶片相对含水量提升4%~16%；同时干旱胁迫下接种组植株组织内的抗氧化酶与脯氨酸水平显著降低，表明处理植株所承受的胁迫压力更低。该效应在雨养种植条件下可转化为13%~15%的产量提升。本研究证实，源自拉贾斯坦邦西部干旱区域的耐胁迫PGPR，不仅可促进干旱区豆科作物的生长，还能提升其干旱胁迫抗性，且在可持续干旱农业系统中具备潜在应用价值。