Downregulation of the ypdA Gene Encoding an Intermediate of His-Asp Phosphorelay Signaling in Aspergillus nidulans Induces the Same Cellular Effects as the Phenylpyrrole Fungicide Fludioxonil

Akira Yoshimi; Daisuke Hagiwara; Miyako Ono; Yasuyuki Fukuma; Yura Midorikawa; Kentaro Furukawa; Tomonori Fujioka; Osamu Mizutani; Natsuko Sato; Ken Miyazawa; Jun-Ichi Maruyama; Junichiro Marui; Youhei Yamagata; Tasuku Nakajima; Chihiro Tanaka; Keietsu Abe

doi:10.3389/ffunb.2021.675459

Downregulation of the ypdA Gene Encoding an Intermediate of His-Asp Phosphorelay Signaling in Aspergillus nidulans Induces the Same Cellular Effects as the Phenylpyrrole Fungicide Fludioxonil

Front Fungal Biol. 2021 Sep 1:2:675459. doi: 10.3389/ffunb.2021.675459. eCollection 2021.

Authors

Akira Yoshimi^{1

2}, Daisuke Hagiwara^{1

3}, Miyako Ono⁴, Yasuyuki Fukuma⁴, Yura Midorikawa⁴, Kentaro Furukawa⁵, Tomonori Fujioka⁵, Osamu Mizutani⁴, Natsuko Sato⁵, Ken Miyazawa⁴, Jun-Ichi Maruyama^{6

7}, Junichiro Marui¹, Youhei Yamagata⁵, Tasuku Nakajima⁵, Chihiro Tanaka⁸, Keietsu Abe^{1

4

5}

Affiliations

¹ New Industry Creation Hatchery Center, Tohoku University, Sendai, Japan.
² Laboratory of Environmental Interface Technology of Filamentous Fungi, Kyoto University, Kyoto, Japan.
³ Medical Mycology Research Center, Chiba University, Chiba, Japan.
⁴ Laboratory of Applied Microbiology, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
⁵ Laboratory of Enzymology, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
⁶ Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
⁷ Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan.
⁸ Terrestrial Microbial Ecology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.

Abstract

Many eukaryotic histidine-to-aspartate (His-Asp) phosphorelay systems consist of three types of signal transducers: a His-kinase (HK), a response regulator (RR), and a histidine-containing phosphotransfer intermediate (HPt). In general, the HPt acts as an intermediate between the HK and the RR and is indispensable for inducing appropriate responses to environmental stresses. In a previous study, we attempted but were unable to obtain deletion mutants of the ypdA gene in order to characterize its function in the filamentous fungus Aspergillus nidulans. In the present study, we constructed the CypdA strain in which ypdA expression is conditionally regulated by the A. nidulans alcA promoter. We constructed CypdA strains with RR gene disruptions (CypdA-sskAΔ, CypdA-srrAΔ, and CypdA-sskAΔsrrAΔ). Suppression of YpdA induced by ypdA downregulation activated the downstream HogA mitogen-activated protein kinase cascade. YpdA suppression caused severe growth defects and abnormal hyphae, with features such as enhanced septation, a decrease in number of nuclei, nuclear fragmentation, and hypertrophy of vacuoles, both regulated in an SskA-dependent manner. Fludioxonil treatment caused the same cellular responses as ypdA suppression. The growth-inhibitory effects of fludioxonil and the lethality caused by ypdA downregulation may be caused by the same or similar mechanisms and to be dependent on both the SskA and SrrA pathways.

Keywords: Aspergillus nidulans; His-Asp phosphorelay signaling; YpdA; fludioxonil; growth disorders; mitogen-activated protein kinases; response regulators.