BdAreA regulates nitrogen metabolism, stress response, and virulence in Botryosphaeria dothidea

The GATA-family transcription factor AreA is a central regulator of nitrogen metabolism in filamentous fungi, and it exhibits significant functional divergence among different fungal species. In this study, using Botryoschaeria dothidea ( B. dothidea ), the causal agent of apple ring rot, as the target organism, we systematically characterized the pleiotropic functions of BdAreA (GATA-type zinc-finger transcription factor AreA of B. dothidea ) through targeted gene knockout. Phenotypic analysis showed that conidiation production was inhibited in Δ BdAreA , and its pathogenicity was significantly attenuated. In addition, the mutant exhibited sensitivity to both hydrogen peroxide and phytoalexins. Notably, BdAreA specifically regulated the utilization of nitrate (NO₃⁻), and combined real-time quantitative PCR (RT-qPCR) and enzyme activity assays confirmed that it positively regulates both the transcriptional level and catalytic activity of nitrate reductase (BdNR) and nitrite reductase (BdNIR) of B. dothidea . More importantly, this study revealed for the first time that BdAreA negatively regulates the expression of BdHog1 and affects its phosphorylation level. Our results demonstrate that BdAreA is a master regulator controlling growth, development, pathogenicity, stress response, and nitrogen metabolism in B. dothidea while also providing important theoretical insights into the link between nitrogen metabolic pathways and mitogen-activated protein kinase (MAPK) signaling cascades.