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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.

Drought is a major environmental stress that limits potato (Solanum tuberosum L.) production worldwide. The transcription factor DREB1A/CBF3 specifically interacts with the dehydration responsive element (DRE/CRT) and induces expression of genes involved in environmental stress tolerance in Arabidopsis thaliana. In this study, DREB1A of A. thaliana was overexpressed in a potato cultivar Longshu 3 (L3) through Agrobacterium tumefaciens-mediated transformation. The transformation and overexpression of DREB1A were assessed using PCR, Southern blotting and semi-quantitative RT-PCR analysis. The results clearly confirmed that the DREB1A gene was successfully integrated into the genome and expressed. When pot-grown plants with 15-16 leaves were subjected to drought stress treatments by withholding water for 8 days, the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), the MDA content and electrolyte leakage in leaves from both non-transgenic and transgenic L3 plants leaves increased. The average activities of SOD, CAT, and POD in transgenic plant leaves, respectively showed 69.77, 60.78, and 24.60% increase than those of non-transgenic L3. The MDA content and electrolyte leakage in non-transgenic L3 plant leaves, respectively increased 59.09 and 37.63% relative to those of transgenic plant leaves. When water was withheld for 14 days control plants exhibited severe wilting and transgenic plants only partially wilting. These results demonstrated that overexpression of DREB1A resulted in improved drought stress tolerance in S. tuberosum plants.