Improving Resistance of Mango to Colletotrichum gloeosporioides by Activating Reactive Oxygen Species and Phenylpropane Metabolism of Bacillus amyloliquefaciens GSBa-1

Abstract

This study aimed to explore the effects of Bacillus amyloliquefaciens GSBa-1 treatment on anthracnose disease resistance and the metabolism of reactive oxygen species (ROS) and phenylpropanoids in mangoes during storage. Mangoes were soaked in a solution containing 1 × 108 CFU/mL of B. amyloliquefaciens GSBa-1. The anthracnose disease incidence, disease index, respiration intensity, ethylene release, reactive oxygen species content, and the activities of related metabolic enzymes, phenylpropanoid-related metabolic enzymes, and phenolic acids in the skin and pulp of mangoes were investigated under normal temperature storage conditions. The results showed that the antagonistic bacterial treatment (ABT) did not significantly inhibit the growth of Colletotrichum gloeosporioides in vitro. However, it significantly reduced the incidence of mango anthracnose disease when applied to the mango peel. ABT enhanced the latent resistance of mango to anthracnose disease by activating its reactive oxygen and phenylpropanoid metabolism. It maintained higher levels of ROS production and elimination in the peel. Moreover, it rapidly activated manganese superoxide dismutase, induced the accumulation of H2O2, and enhanced the activity of manganese superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase in the mango peel. Furthermore, ABT activated phenylalanine ammonia-lyase, cinnamic acid-4-hydroxylase, 4-coumaroyl-CoA ligase, and cinnamyl alcohol dehydrogenase in the mango peel and pulp, promoting the accumulation of antifungal phenolic acids such as gallic acid, catechins, and ellagic acid. Bacillus amyloliquefaciens GSBa-1 may be a potent inhibitor of mango anthracnose, primarily enhancing the resistance of mangoes to anthracnose by synergistically activating ROS in the peel and phenylpropanoid metabolism in the pulp, thereby reducing the incidence of anthracnose effectively.