Salinity is one of the most important factors that limit the productivity of agricultural soils. Certain plant growth-promoting bacteria (PGPB) have the ability to stimulate the growth of crop plants even under salt stress. In the present study, we analysed the potential of PGPB Bacillus toyonensis COPE52 to improve the growth of tomato plants and its capacity to modify its membrane lipid and fatty acid composition under salt stress. Thus, strain COPE52 increased the relative amount of branched chain fatty acids (15:0i and 16:1∆9) and accumulation of an unknown membrane lipid, while phosphatidylethanolamine (PE) levels decreased during growth with 100 and 200 mM NaCl. Importantly, direct and indirect plant growth-promoting (PGP) mechanisms of B. toyonensis COPE52, such as indole-3-acetic acid (IAA), protease activity, biofilm formation, and antifungal activity against Botrytis cinerea, remained unchanged in the presence of NaCl in vitro, compared to controls without salt. In a greenhouse experiment, tomato plants (Lycopersicon esculentum ‘Saladette’) showed increased shoot and root length, higher dry biomass, and chlorophyll content when inoculated with B. toyonensis COPE52 at 0 and 100 mM NaCl. In summary, these results indicate that Bacillus toyonensis COPE52 can modify cell membrane lipid components as a potential protecting mechanism to maintain PGP traits under saline-soil conditions.

中文翻译：

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Bacillus toyonensis COPE52 改变脂质和脂肪酸组成，表现出抗真菌活性，并刺激盐水条件下番茄植物的生长

盐度是限制农业土壤生产力的最重要因素之一。某些植物生长促进细菌 (PGPB) 即使在盐胁迫下也能刺激作物生长。在本研究中，我们分析了 PGPB Bacillus toyonensis COPE52 改善番茄植株生长的潜力及其在盐胁迫下改变其膜脂和脂肪酸组成的能力。因此，菌株 COPE52 增加了支链脂肪酸（15:0i 和 16:1∆9）的相对量和未知膜脂的积累，而磷脂酰乙醇胺 (PE) 水平在 100 和 200 mM NaCl 的生长过程中降低。重要的是，B. toyonensis COPE52 的直接和间接植物生长促进 (PGP) 机制，例如吲哚-3-乙酸 (IAA)、蛋白酶活性、生物膜形成、与没有盐的对照相比，在体外存在 NaCl 的情况下，对灰霉病菌的抗真菌活性保持不变。在温室实验中，番茄植物（Lycopersicon esculentum 'Saladette'）在接种 0 和 100 mM NaCl 的 B. toyonensis COPE52 时表现出增加的枝条和根长度、更高的干生物量和叶绿素含量。总之，这些结果表明，Bacillus toyonensis COPE52 可以修饰细胞膜脂质成分，作为在盐渍土壤条件下维持 PGP 性状的潜在保护机制。接种 0 和 100 mM NaCl 的 B. toyonensis COPE52 时的叶绿素含量。总之，这些结果表明，Bacillus toyonensis COPE52 可以修饰细胞膜脂质成分，作为在盐渍土壤条件下维持 PGP 性状的潜在保护机制。接种 0 和 100 mM NaCl 的 B. toyonensis COPE52 时的叶绿素含量。总之，这些结果表明，Bacillus toyonensis COPE52 可以修饰细胞膜脂质成分，作为在盐渍土壤条件下维持 PGP 性状的潜在保护机制。