Abstract Salinity stress is a major limiting factor that adversely affects the crop productivity. Considering these problems, present investigation was aimed to isolate and characterize a halotolerant PGPR strain to circumvent these problems. Strain MSK1 tolerated exceptionally 1000 mM of NaCl and identified as K. sacchari using 16S rRNA sequence analysis (accession number MG028651). Strain MSK1 was found metabolically active, producing substantial amount of growth regulating substances such as indole-3-acetic acid, ACC deaminase, siderophore, ammonia and hydrogen cyanide which, however, increased with increasing NaCl concentrations. Vigna radiata was used as test crop to evaluate the effect of NaCl as well as remediating potential of halotolerant K. sacchari. Phytotoxicity of salt to V. radiata plants was obvious under both in vitro and in vivo environments and increased in a dose related manner. Among the concentrations, the higher NaCl level (400 mM) exhibited more pronounced detrimental effect and significantly (P ≤ 0.05) decreased the germination attributes, dry biomass, photosynthetic pigments, symbiotic features and seed yield of V. radiata. However, antioxidant enzymes, proline, MDA, membrane damage, H2O2 content, relative leaf water content (RLWC) and Na+/K+ ion concentrations were increased with increasing NaCl concentrations. Contrarily, following soil inoculation, halotolerant K. sacchari MSK1 alleviated the salinity stress and improved the plant performance and augmented the dry biomass, chlorophyll formation, symbiosis and yield of V. radiate even in salt stressed condition. Besides these, strain MSK1 reduced the level of proline, MDA, H2O2 and antioxidant enzyme activity. Additionally, RLWC, membrane injury and Na+/K+ ions were reduced following the application of K. sacchari. The root colonization efficiency of K. sacchari even under salinity stress was examined by scanning electron microscopy. Conclusively, it can surely be suggested that halotolerant MSK1 strain could inexpensively be explored as best choice for augmenting the V. radiata production under salinity stressed soils.

中文翻译：

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耐盐细菌 Kosakonia sacchari 对辐射豇豆的定植改善了离子平衡、应激代谢物、抗氧化状态和 NaCl 胁迫下的产量

摘要 盐胁迫是影响作物生产力的主要限制因素。考虑到这些问题，本研究旨在分离和表征耐盐 PGPR 菌株以规避这些问题。菌株 MSK1 能够耐受 1000 mM 的 NaCl，并使用 16S rRNA 序列分析（登录号 MG028651）鉴定为 K. sacchari。发现菌株 MSK1 具有代谢活性，产生大量的生长调节物质，如吲哚-3-乙酸、ACC 脱氨酶、铁载体、氨和氰化氢，然而，这些物质随着 NaCl 浓度的增加而增加。Vigna radiata 被用作测试作物以评估 NaCl 的效果以及耐盐 K. sacchari 的修复潜力。盐对 V 的植物毒性。辐射植物在体外和体内环境下均明显，并呈剂量相关增加。在这些浓度中，较高的 NaCl 水平 (400 mM) 表现出更显着的不利影响，并且显着 (P ≤ 0.05) 降低了 V. radiata 的发芽属性、干生物量、光合色素、共生特征和种子产量。然而，抗氧化酶、脯氨酸、MDA、膜损伤、H2O2 含量、相对叶含水量 (RLWC) 和 Na+/K+ 离子浓度随着 NaCl 浓度的增加而增加。相反，在土壤接种后，耐盐 K. sacchari MSK1 减轻了盐分胁迫，改善了植物性能，并增加了 V. radiate 的干生物量、叶绿素形成、共生和产量，即使在盐胁迫条件下也是如此。除了这些，菌株 MSK1 降低了脯氨酸、MDA、H2O2 和抗氧化酶活性的水平。此外，使用糖衣甘蓝后 RLWC、膜损伤和 Na+/K+ 离子都减少了。通过扫描电子显微镜检查即使在盐分胁迫下 K. sacchari 的根定植效率。最后，可以肯定地表明，耐盐 MSK1 菌株可以廉价地探索作为在盐胁迫土壤下增加辐射弧菌产量的最佳选择。