The effects and mechanisms on abiotic and biotic stress tolerance of Chinese cabbages induced by Bacillus mycoides

Abstract

Bacillus mycoides (BM) is a rhizosphere-associated bacterium with plant growth-promoting property. In agriculture, applications of BM have been reported to have beneficial effects on plant against biotic and abiotic stresses. This research is to evaluate the beneficial effects of BM (BM02 isolate) on Chinese cabbage under biotic and abiotic stresses. First of all, the interactions between BM02 and various stresses were assessed. Secondly, BM02-treated Chinese cabbages were subjected to different stresses and the effects of BM treatment under these stresses were evaluated. Lastly, defense-related genes expressions of BM02-treated Chinese cabbage with and without pathogen inoculation were analyzed to uncover the mechanisms of BM02 beneficial effects. BM02 showed higher adaptability in mild salinity and higher temperature, and demonstrated significant inhibition on the growth of Fusarium oxysporum f. sp. rapae (F43). BM02 treatments also enhanced tolerance to salt stress during Chinese cabbage seed germination. Additionally, Chinese cabbage seedlings showed decreased wilt disease index during F-43 infection after BM02 treatments. Genes expressions of Chinese cabbage seedlings demonstrated that salicylic acid and jasmonic acid signaling-related genes were induced by BM02 pre-treatments after F-43 inoculation and differences in gene expressions were observed in different Chinese cabbage lines. In conclusion, BM02 could promote the growth, enhances stress tolerance, and showed biocontrol potential to Fusarium yellows in Chinese cabbage.