FgRIC8 is involved in regulating vegetative growth, conidiation, deoxynivalenol production and virulence in Fusarium graminearum.
Proteins of the resistance to inhibitors of cholinesterase 8 (Ric8) group act as guanine nucleotide exchange factors (GEFs) and play important roles in regulating G-protein signaling in animals. In filamentous fungi, putative Ric8 orthologs have so far been identified in Magnaporthe oryzae, Neurospora crassa, Aspergillus nidulans and Aspergillus fumigatus. Here, we report the functional investigation of a potential RIC8 ortholog (FgRIC8) in the wheat head blight pathogen Fusarium graminearum. Targeted gene deletion mutants of FgRIC8 exhibited a significant reduction in vegetative growth, conidiation, pigment production as well as deoxynivalenol (DON) biosynthesis. Pathogenicity assays using a point-inoculated spikelet approach showed that the mutants were severely impaired in virulence on flowering wheat heads. Quantitative RT-PCR analysis revealed that genes encoding F. graminearum Gα (FgGpa1 and FgGpa3), Gβ (FgGpb1) and Gγ (FgGpg1) subunits were significantly down-regulated in Fgric8 mutants. Moreover, we showed that FgRic8 physically interacts with both FgGpa1 and FgGpa3, but not FgGpa2, in yeast two-hybrid assays. The intracellular cAMP levels in Fgric8 mutants were significantly decreased compared to the isogenic wild-type strain. Taken together, our results indicate that FgRic8 plays critical roles in fungal development, secondary metabolism and virulence in F. graminearum and may act as a regulator of G protein alpha subunits.
Institute of Biotechnology, Zhejiang University, Hangzhou 310025, China.
Jinjin
J
Wu
Institute of Biotechnology, Zhejiang University, Hangzhou 310025, China.
Yuting
Y
Liu
Institute of Biotechnology, Zhejiang University, Hangzhou 310025, China.
Wuyun
W
Lv
Institute of Biotechnology, Zhejiang University, Hangzhou 310025, China.
Xiaofeng
X
Yue
Institute of Biotechnology, Zhejiang University, Hangzhou 310025, China.
Yawei
Y
Que
Institute of Biotechnology, Zhejiang University, Hangzhou 310025, China.
Nan
N
Yang
Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Zhengguang
Z
Zhang
Institute of Biotechnology, Zhejiang University, Hangzhou 310025, China.
Zhonghua
Z
Ma
School of Biosciences, University of Exeter, Geoffrey Pope Building, Exeter EX4 4QD, United Kingdom.
Nicholas J
NJ
Talbot
Institute of Biotechnology, Zhejiang University, Hangzhou 310025, China. Electronic address: zhywang@zju.edu.cn.
Zhengyi
Z
Wang
D002678:Chimera; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005670:Fusarium / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D017353:Gene Deletion; D005800:Genes, Fungal; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D025301:Hyphae; D009154:Mutation; D012100:Reproduction, Asexual; D013172:Spores, Fungal; D014255:Trichothecenes / Q000096:biosynthesis*; D014908:Triticum / Q000382:microbiology; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
D005656:Fungal Proteins; D020662:Guanine Nucleotide Exchange Factors; D014255:Trichothecenes; D037521:Virulence Factors; C007262:deoxynivalenol
DON production; FgRIC8; Fusarium graminearum; G proteins; Virulence; cAMP signaling