Biocontrol potential and mechanism of action of Bacillus tequilensis JK-11 against Bipolaris sorokiniana.

Abstract

Root rot of wheat, caused by the pathogen Bipolaris sorokiniana, has emerged as a major concern for wheat yield damage and food security in central China. Given their environmentally friendly nature, biological control methods are becoming increasingly popular. We conducted a study to assess the antagonistic effect of Bacillus tequilensis JK-11 on B. sorokiniana. Spore germination and mycelial dry weight of B. sorokiniana decreased by 84.9% and 80.63% after JK-11 culture filtrate treatment with a concentration of 20%. SEM observed significant damage to the microscopic morphology of B. sorokiniana cells, and LSCM observed significant apoptosis of B. sorokiniana mycelial cells in the treated group, in addition to changes in ergosterol and electrical conductivity suggesting elevated mycelial cell membrane permeability. In contrast to the untreated group, CF-treated B. sorokiniana cells showed significant DNA and mitochondrial damage and excessive accumulation of reactive oxygen species. The activities of antioxidant enzymes and key enzymes involved in metabolic processes were significantly impaired in mycelial cells treated with different concentrations of CF. Wheat potting experiments using JK-11 revealed its ability to stabilize wheat root colonization for a certain period. Moreover, the bacterial suspension of JK-11 had a significant impact on wheat root rot prevention post-irrigation. The study results suggest that JK-11 strain of B. tequilensis exhibits great potential for controlling wheat root rot and offers a fresh approach to wheat management.