The MiTGA1 stimulates MiPR1 expression and H2O2 production to enhance mango disease resistance in response to Bacillus siamensis treatment

Abstract

Postharvest disease caused by fungi is a major issue that leads to quality decline and economic losses in mango fruit during storage and distribution. TGA transcription factors and pathogenesis-related proteins (PR) play crucial roles in modulating plant tolerance to pathogens. However, the roles of TGAs in the disease resistance of mango fruit remain unclear. Here, we investigated the impact of applying the antagonist Bacillus siamensis (N-1) on disease occurrence and the expression levels of MiTGA1 and MiPR1 genes in “Tainong No. 1” mango. We also explored the molecular mechanism of MiTGA1 interaction with MiPR1 gene. Results demonstrated that N-1 treatment significantly increased the level of hydrogen peroxide (H₂O₂) and effectively suppressed disease expansion during mango storage at 25 °C. Analyses of transcriptome data and qRT-PCR revealed the obvious up-regulation of MiTGA1 and MiPR1 genes in response to the N-1 treatment. Further subcellular localization identified the MiTGA1 protein as being located in the nucleus. Yeast one-hybrid (Y1H) and dual-luciferase reporter (DLR) assays confirmed that MiTGA1 could bind to the MiPR1 promoter and activate its transcription. Furthermore, transient over-expression of MiTGA1 in mango was found to enhance the accumulation of disease-resistant substances such as H₂O₂ by modulating MiPR1 expression, thereby bolstering the disease resistance of mango fruit. Our study suggests that MiTGA1 is a promising target gene and its interaction with MiPR1 may contribute to disease resistance induction and decay mitigation in postharvest mango fruit.