Effects of Tsukamurella tyrosinosolvens P9 on growth, physiology and antioxdant enzyme of peanut under drought stress and after re-watering.

Background: The plant-growth-promoting rhizobacterium Tsukamurella tyrosinosolvens is a rare strain of actinomycete, in order to recognize and expand the ecological functions of rare actinomycetes. Methods: In this experiment, we studied the effect of Tsukamurella tyrosinosolvens P9 on the drought resistance of peanut by inoculating peanut seedlings in pots and measuring the growth and physiological indicators of peanut under drought stress and re-watering conditions. Results: The results showed that during drought stress, the relative water content of the soil and leaves, chlorophyll content, and stomatal length, width, and aperture were significantly decreased while the levels of malondialdehyde (MDA), H2O2 and stomatal density were significantly increased. Peanut growth was also inhibited. However, inoculation with the P9 strain significantly promoted the growth of peanut under drought stress as plant height, fresh weight, root length and root weight were significantly higher compared with the uninoculated drought stress group. In addition, in P9-inoculated plants, the water and chlorophyll contents were significantly higher and the activities of the antioxidant enzymes CAT and SOD were significantly increased (except during the six days of drought treatment). While the stomatal length, width, and aperture were improved, the levels of MDA and H2O2 were significantly decreased. NBT staining showed that inoculation with P9 reduced O2− accumulation under stress. After re-watering, the physiological indexes of inoculated plants recovered more quickly and grew better. Conclusions: The results showed that T. tyrosinosolvens P9 enhanced drought resistance and improves peanut growth by increasing leaf water content, increasing photosynthesis, regulating stomatal closure, and improving antioxidant enzyme activity. [ABSTRACT FROM AUTHOR]