Abstract High salinity is harmful for crop physiology and yield. Accumulating evidences indicate that plant growth promoting rhizobacteria (PGPR) can enhance crop growth and reduce the negative impacts of salt stress through regulation of some molecular, biochemical and physiological features. In the present study, a novel halo-tolerant strain Y1 was isolated from maize rhizosphere soil. Sequence analysis of 16S rRNA gene confirmed its identity as Kocuria rhizophila. This strain tolerated up to 10 % NaCl and showed two growth promoting traits like phosphate solubilization and IAA production. The impacts of K. rhizophila Y1 on maize (Zea mays L.) growth and development with salt treatment (0, 100 and 200 mM NaCl) were further examined. The results showed that inoculation with K. rhizophila Y1 strain could protect maize from salt stress by regulating plant hormones (IAA and ABA) levels and improving nutrient acquisition. In detail, inoculation with K. rhizophila Y1 significantly improved growth performance, biomass production, seed germination rate, photosynthetic capacity, antioxidant levels, relative water content and chlorophyll accumulation in maize under saline conditions in comparison with non-inoculation treatment. Moreover, strain Y1 inoculated maize showed lower levels of Na+ and electrolyte leakage under salt treatment compared to non-inoculated ones. Inoculated maize also showed higher transcript levels of genes encoding antioxidants (ZmGR1 and ZmAPX1) and genes involved in salt tolerance (ZmNHX1, ZmNHX2, ZmNHX3, ZmWRKY58 and ZmDREB2A) than in non-inoculated plants. In summary, this study indicated the important contribution of K. rhizophila Y1 in mitigating the deleterious effects of salinity on maize growth and development by regulating plant hormones and nutrient acquisition, and thereby maintaining ion homeostasis, improving photosynthetic capacity, enhancing redox potential and stress-responsive genes expression.

中文翻译：

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一种新型 PGPR 菌株 Kocuria rhizophila Y1 通过调节植物激素水平、养分获取、氧化还原电位、离子稳态、光合能力和胁迫响应基因表达来增强玉米的盐胁迫耐受性

摘要 高盐度对作物生理和产量有害。越来越多的证据表明，植物促生根际细菌（PGPR）可以通过调节一些分子、生化和生理特征来促进作物生长并减少盐胁迫的负面影响。在本研究中，从玉米根际土壤中分离出一种新型耐光菌株 Y1。16S rRNA 基因的序列分析证实其身份为 Kocuria rhizophila。该菌株可耐受高达 10% 的 NaCl，并显示出两种促进生长的特性，如溶解磷酸盐和产生 IAA。进一步研究了 K. rhizophila Y1 对盐处理（0、100 和 200 mM NaCl）下玉米（Zea mays L.）生长和发育的影响。结果表明，接种 K. rhizophila Y1 菌株可以通过调节植物激素（IAA 和 ABA）水平和改善养分获取来保护玉米免受盐胁迫。具体而言，与未接种处理相比，在盐渍条件下，接种 K. rhizophila Y1 显着提高了玉米的生长性能、生物量产量、种子发芽率、光合能力、抗氧化水平、相对含水量和叶绿素积累。此外，与未接种的玉米相比，菌株 Y1 接种的玉米在盐处理下显示出较低水平的 Na+ 和电解质泄漏。与未接种的植物相比，接种的玉米还显示出更高的编码抗氧化剂基因（ZmGR1 和 ZmAPX1）和耐盐基因（ZmNHX1、ZmNHX2、ZmNHX3、ZmWRKY58 和 ZmDREB2A）的转录水平。总之，