It has been reported that drought stress adversely affects the growth and yield of Glycyrrhiza uralensis, Chinese liquorice, in agricultural production. Bacillus pumilus, an important plant growth-promoting bacterium, play a significant role in improving plant tolerance to abiotic stress. However, the role of Bacillus pumilus G5 in resisting drought stress is largely unknown. In the present study we found that drought stress significantly inhibited the growth and reduced the biomass of G. uralensis seedlings by restraining C- and N-metabolism, while this could be effectively reversed by B. pumilus G5 inoculation. Specifically, B. pumilus G5 significantly increased the content of primary metabolites such as soluble sugar, soluble protein and free amino acids by regulating the C and N metabolic processes in G. uralensis seedlings. Moreover, B. pumilus G5 increased the content of glycyrrhizic acid, one of the important secondary metabolites, likely mediated through the increased content of primary metabolites and by recovering the expression of three key enzymes, HMGR, SQS and β-AS, in the biosynthesis of glycyrrhizic acid. Interestingly, the regulating effect of B. pumilus G5 inoculation on promoting the accumulation of glycyrrhizic acid and increasing the expression of synthesis related genes is spatially selective. In summary, our findings suggest that B. pumilus G5 could alleviate adverse effects induced by drought stress on the growth of G. uralensis seedlings by regulating C- and N-metabolisms that further triggered the accumulation of secondary metabolites, and this finally improved the drought tolerance of cultivated G. uralensis seedlings. This article is protected by copyright. All rights reserved.

中文翻译：

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短小芽孢杆菌通过增强初级和次级代谢提高甘草 G5 幼苗的耐旱性

据报道，干旱胁迫对农业生产中甘草（Glycyrrhiza uralensis）的生长和产量产生不利影响。短小芽孢杆菌是一种重要的植物促生长菌，在提高植物对非生物胁迫的耐受性方面发挥着重要作用。然而，短小芽孢杆菌 G5 在抵抗干旱胁迫中的作用在很大程度上是未知的。在本研究中，我们发现干旱胁迫通过抑制 C 和 N 代谢显着抑制 G. uralensis 幼苗的生长并降低其生物量，而这可以通过 B. pumilus G5 接种有效逆转。具体而言，短小芽孢杆菌 G5 通过调节 G. uralensis 幼苗的 C 和 N 代谢过程，显着增加了可溶性糖、可溶性蛋白质和游离氨基酸等初级代谢物的含量。此外，B. pumilus G5 增加了甘草酸的含量，甘草酸是重要的次生代谢产物之一，这可能是通过增加初级代谢产物的含量以及恢复甘草酸生物合成中三种关键酶 HMGR、SQS 和 β-AS 的表达来介导的。有趣的是，短小芽孢杆菌G5接种对促进甘草酸积累和增加合成相关基因表达的调节作用具有空间选择性。总之，我们的研究结果表明 B. pumilus G5 可以通过调节 C- 和 N- 代谢，进一步触发次生代谢物的积累，从而减轻干旱胁迫对 G. uralensis 幼苗生长的不利影响，最终改善干旱栽培 G. uralensis 幼苗的耐受性。本文受版权保护。