Abstract Stevia (Stevia rebaudiana Bertoni) is a salt-sensitive herb with sweet leaves without side effects for diabetic patients. The present research was conducted to investigate the effect of endophytic fungus Piriformospora indica and two bacterial isolates, namely of Streptomyces sp. (kj152148) and (kj152149) with Stevia host plants. These microbial isolates were utilized as growth-promoting agents for induction of salt stress tolerance and secondary metabolite accumulation in inoculated plants. The present experiment was designed as factorial basis experiment based on a completely randomized design with six replications undertaken in two consecutive years (2016-2017). Treatments included three levels of salinity [0.85 (control), 1.5 and 3 dS/m] and four levels of plant growth-promoting microorganisms [no-inoculation, Piriformospora indica, Kj152148 Streptomyces sp (S1) and K152149 Streptomyces sp (S2)]. Under stress and non-stress conditions, endophytic fungus and bacterial isolates had significant positive effect on the recorded biochemical and physiological parameters of stevia. Inoculation of fungus and bacterial isolates reduced the negative effects of salinity stress by increasing antioxidant enzymes and free radical scavenging activity, phenol and flavonoid accumulation and total glucose and proline concentrations. From the results it may be concluded that, indicated a positive effect of applied fungus and bacterial treatments on the resistance of stevia plant to the salinity stress and due to the relative susceptibility of stevia to salinity, pre-treatment of the plant using of the desired microbes is recommended before planting in soil areas susceptible to salinity.

中文翻译：

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盐胁迫下甜叶菊植物对促生长微生物的植物化学反应

摘要 甜叶菊（Stevia rebaudiana Bertoni）是一种对盐敏感的草本植物，叶甘甜，对糖尿病患者无副作用。本研究旨在调查内生真菌 Piriformospora indica 和两种细菌分离物，即 Streptomyces sp. 的影响。(kj152148) 和 (kj152149) 与甜菊宿主植物。这些微生物分离物被用作生长促进剂，用于诱导接种植物的盐胁迫耐受性和次生代谢物积累。本实验设计为基于完全随机设计的因子基础实验，连续两年（2016-2017）进行六次重复。处理包括三个水平的盐度 [0.85（对照）、1.5 和 3 dS/m] 和四个水平的植物生长促进微生物 [不接种，Piriformospora indica，Kj152148 链霉菌属 (S1) 和 K152149 链霉菌属 (S2)]。在压力和非压力条件下，内生真菌和细菌分离物对甜叶菊的生化和生理参数记录具有显着的积极影响。真菌和细菌分离物的接种通过增加抗氧化酶和自由基清除活性、苯酚和黄酮类化合物的积累以及总葡萄糖和脯氨酸浓度来减少盐分胁迫的负面影响。从结果可以得出结论，表明应用真菌和细菌处理对甜菊植物对盐分胁迫的抗性有积极影响，并且由于甜菊对盐分的相对敏感性，使用所需的植物预处理建议在易受盐分影响的土壤区域种植之前使用微生物。