FgVps9, a Rab5 GEF, Is Critical for DON Biosynthesis and Pathogenicity in Fusarium graminearum

Chengdong Yang; Jingjing Li; Xin Chen; Xingzhi Zhang; Danhua Liao; Yingzi Yun; Wenhui Zheng; Yakubu Saddeeq Abubakar; Guangpu Li; Zonghua Wang; Jie Zhou

doi:10.3389/fmicb.2020.01714

FgVps9, a Rab5 GEF, Is Critical for DON Biosynthesis and Pathogenicity in Fusarium graminearum

Front Microbiol. 2020 Aug 4:11:1714. doi: 10.3389/fmicb.2020.01714. eCollection 2020.

Authors

Chengdong Yang^{1

2}, Jingjing Li^{1

2}, Xin Chen^{1

2}, Xingzhi Zhang^{1

2}, Danhua Liao^{1

2}, Yingzi Yun², Wenhui Zheng², Yakubu Saddeeq Abubakar³, Guangpu Li⁴, Zonghua Wang^{1

2

5}, Jie Zhou^{1

2}

Affiliations

¹ Fujian Province Key Laboratory of Pathogenic Fungi and Mycotoxins and College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.
² State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China.
³ Department of Biochemistry, Ahmadu Bello University, Zaria, Nigeria.
⁴ Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.
⁵ Institute of Oceanography, Minjiang University, Fuzhou, China.

Abstract

Rab GTPases play an important role in vesicle-mediated membrane trafficking in eukaryotes. Previous studies have demonstrated that deletion of RAB5/VPS21 reduces endocytosis and virulence of fungal phytopathogens in their host plants. However, Rab5 GTPase cycle regulators have not been characterized in Fusarium graminearum, the causal agent of Fusarium head blight (FHB) or head scab disease in cereal crops. In this study, we have identified and characterized a Rab5 guanine nucleotide exchange factor (GEF), the Vps9 homolog FgVps9, in F. graminearum. Yeast two hybrid (Y2H) assays have shown that FgVps9 specifically interacts with the guanosine diphosphate (GDP)-bound (inactive) forms of FgRab51 and FgRab52, the Rab5 isoforms in F. graminearum. Deletion of FgVPS9 shows impaired fungal growth and conidiation. Pathogenicity assays indicate that deletion of FgVPS9 can significantly decrease the virulence of F. graminearum in wheat. Cytological analyses have indicated that FgVps9 colocalizes with FgRab51 and FgRab52 on early endosomes and regulates endocytosis and autophagy processes. Gene expression and cytological examination have shown that FgVps9 and FgRab51 or FgRab52 function in concert to control deoxynivalenol (DON) biosynthesis by regulating the expression of trichothecene biosynthesis-related genes and toxisome biogenesis. Taken together, FgVps9 functions as a GEF for FgRab51 and FgRab52 to regulate endocytosis, which, as a basic cellular function, has significant impact on the vegetative growth, asexual development, autophagy, DON production, and plant infection in F. graminearum.

Keywords: DON; FgVps9; Fusarium graminearum; endocytosis; guanine nucleotide exchange factor; pathogenicity.