Intracellular and mitochondrial proteomic analysis reveals antifungal mechanisms of borate on mango black spot pathogen Alternaria alternata

Abstract

AbstractBoron, in the form of potassium tetraborate, has previously been found to be effective at inhibiting mango black spot disease, caused by Alternaria alternata. However, the mechanisms involved in this inhibition are largely unknown. In this study, A. alternata was treated in vitro with potassium tetraborate at a concentration of 5–10 mM for 48 or 72 h. The intracellular and mitochondrial proteins were extracted from mycelium and separated using two‐dimensional electrophoresis (2‐DE). Differentially expressed proteins (DEPs) were identified using bioinformatics tools and differences between protein spots were derived from mass spectrometry (MS). Using matrix‐assisted laser desorption ionization time‐of‐flight tandem mass spectrometry (MALDI‐ToF‐MS/MS), 96 intracellular and 56 mitochondrial DEPs were identified. The intracellular proteins identified were found to be involved in posttranslational modifications, protein turnover and chaperones, while the mitochondrial proteins were involved in electron transport chains. Our results demonstrate that various metabolic pathways are involved in the antifungal activity of boron. The differential expression of 20 genes was also verified at the mRNA level by reverse transcription‐quantitative PCR. Our study suggests that borate could be used as a potential substitute for synthetic fungicides to control this postharvest disease of mango fruits.