Background and aims

The plant growth promoting rhizobacteria have been extensively implicated in plant responses to changing environments. However, the action mechanisms still need to be elucidated. This study addressed the effect of Paraburkholderia sp. GD17 on rice seedlings in responses to salt stress.

Methods

The experiment consisted of GD17-inoculated and non-inoculated plants, with or without NaCl treatment. Physiological and biochemical parameters, and gene expression were analyzed.

Results

GD17 efficiently colonized inside roots, and provided a protection against salt stress. Following exposure to 68 mM of NaCl for 48 h, although the accumulation of Na⁺ was not affected in GD17-inoculated (+ GD17) roots relative to non-inoculated ones, its concentration was substantially reduced in + GD17 shoots. The contents of K and other mineral elements were higher in + GD17 plants. The expression of Na⁺ and K⁺ transporter-encoding genes generally presented a higher level in + GD17 plants. The antioxidative defense especially related to the removal of H₂O₂ was more strongly activated in + GD17 plants. Correspondingly, salt-induced oxidative damage was significantly ameliorated. A substantial increase in proline content and gene expression was observed in + GD17 plants. Additionally, the cell wall invertase-encoding gene displayed a dramatically higher expression level in + GD17 plants.

Conclusions

GD17 efficiently improved rice seedling tolerance to salt stress. The possible mechanisms might be associated with the absorption and redistribution of mineral elements, the vacuolar sequestration of Na⁺ as well as exclusion of Na⁺, antioxidative defense, the production of proline, and the sucrose catabolism in apoplast.

中文翻译：

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帕拉伯克霍尔德菌属 GD17 提高水稻幼苗耐盐性

背景和目标

促进植物生长的根际细菌广泛参与植物对环境变化的反应。然而，其作用机制仍有待阐明。这项研究解决了Paraburkholderia sp.的影响。GD17 对水稻幼苗盐胁迫的响应。

方法

实验由 GD17 接种和未接种的植物组成，有或没有 NaCl 处理。分析了生理和生化参数以及基因表达。

结果

GD17 有效地在根内定植，并提供对盐胁迫的保护。在暴露于 68 mM NaCl 48 小时后，尽管相对于未接种的根，GD17 接种 (+ GD17) 根中 Na ⁺的积累没有受到影响，但其浓度在 + GD17 芽中显着降低。+ GD17 植株 K 和其他矿质元素含量较高。Na ⁺和K ⁺转运蛋白编码基因的表达通常在+ GD17 植物中呈现较高水平。抗氧化防御尤其与去除 ​​H ₂ O _{2 相关}在+ GD17 植物中被更强烈地激活。相应地，盐诱导的氧化损伤得到显着改善。在 + GD17 植物中观察到脯氨酸含量和基因表达的显着增加。此外，细胞壁转化酶编码基因在 + GD17 植物中显示出显着更高的表达水平。

结论

GD17 有效提高水稻幼苗对盐胁迫的耐受性。可能的机制可能与吸收和矿物元素的再分配，Na组成的液泡封存相关联⁺以及钠的排斥⁺，抗氧化防御，生产脯氨酸，并且在质外体的蔗糖分解代谢。