Growth-promoting bacteria alleviates drought stress of G. uralensis through improving photosynthesis characteristics and water status

Drought has is becoming increasingly serious abiotic stress that influences plant growth. Endophytes are non-pathogenic plant-associated bacteria that can play an important role in conferring plant resistance to drought stress. In this study, drought stress resulted in the evident breakdown of the chloroplast membrane system in leaf cells, whereas Bacillus pumilus inoculation improved the integrity of chloroplast and mitochondria cell structure. Thus chlorophyll content, photosynthetic parameters and water use efficiency increased. The inoculation of endophytes alleviated the inhibitory effect of drought stress on Glycyrrhiza uralensis growth. We concluded that B. pumilus inoculation enhanced the growth and drought tolerance of G. uralensis through the protection of chloroplast submicroscopic structure, and thus increased chlorophyll content, efficient photosynthetic rate, and improved water state.