MaAreB, a GATA Transcription Factor, Is Involved in Nitrogen Source Utilization, Stress Tolerances and Virulence in <i>Metarhizium acridum</i>

• Main Authors: Chaochuang Li, Qipei Zhang, Yuxian Xia, Kai Jin
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Journal of Fungi
• Subjects: <i>Metarhizium acridum</i>; GATA transcription factor; MaAreB; nitrogen utilization; stress response; virulence
• Online Access: https://www.mdpi.com/2309-608X/7/7/512

The nitrogen catabolite repression (NCR) pathway is involved in nitrogen utilization, in which the global GATA transcription factor AreA plays an indispensable role and has been reported in many fungi. However, relatively few studies are focused on AreB, another GATA transcription factor in the NCR pathway and the functions of AreB are largely unknown in entomopathogenic fungi. Here, we characterized MaAreB in the model entomopathogenic fungus <i>Metarhizium acridum</i>. Sequence arrangement found that MaAreB had a conserved GATA zinc finger DNA binding domain and a leucine zipper domain. Disruption of <i>MaAreB</i> affected the nitrogen utilization and led to decelerated conidial germination and hyphal growth, decreased conidial yield, and lower tolerances to UV-B irradiation and heat-shock. Furthermore, the <i>MaAreB</i> mutant (Δ<i>MaAreB</i>) exhibited increased sensitivity to CFW (Calcofluor white), decreased cell wall contents (chitin and β-1,3-glucan) and reduced expression levels of some genes related to cell wall integrity, indicating that disruption of <i>MaAreB</i> affected the cell wall integrity. Bioassays showed that the virulence of the Δ<i>MaAreB</i> strain was decreased in topical inoculation but not in intra-hemocoel injection. Consistently, deletion of <i>MaAreB</i> severely impaired the appressorium formation and reduced the turgor pressure of appressorium. These results revealed that <i>MaAreB</i> regulated fungal nitrogen utilization, cell wall integrity and biological control potential, which would contribute to the functional characterization of AreB homologous proteins in other insect fungal pathogens, and even filamentous fungi.