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 ΔBdAreA, 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.