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

## TL;DR

This study shows that the BdAreA gene in Botryosphaeria dothidea controls growth, stress response, and disease-causing ability, and is key to nitrogen metabolism.

## Contribution

The study reveals that BdAreA negatively regulates BdHog1 and connects nitrogen metabolism to MAPK signaling in B. dothidea.

## Key findings

- BdAreA knockout reduces spore production and pathogenicity in B. dothidea.
- BdAreA positively regulates nitrate reductase and nitrite reductase activity.
- BdAreA negatively regulates BdHog1 expression and phosphorylation.

## Abstract

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.

The online version contains supplementary material available at 10.1007/s44297-026-00065-8.