FgIlv5 is required for branched-chain amino acid biosynthesis and full virulence in Fusarium graminearum.
In this study, we characterized FgIlv5, a homologue of the Saccharomyces cerevisiae keto-acid reductoisomerase (KARI) from the important wheat head scab fungus Fusarium graminearum. KARI is a key enzyme in the branched-chain amino acid (BCAA, including leucine, isoleucine and valine) biosynthetic pathway that exists in a variety of organisms from bacteria to fungi and higher plants, but not in mammals. The FgILV5 deletion mutant ΔFgIlv5-4 failed to grow when the culture medium was nutritionally limited for BCAAs. When grown on potato-dextrose agar plates, ΔFgIlv5-4 exhibited a significant decrease in aerial hyphae formation and red pigmentation. Conidia formation was also blocked in ΔFgIlv5-4. Exogenous addition of 1 mM isoleucine and valine was able to rescue the defects of mycelial growth and conidial morphogenesis. Cellular stress assays showed that ΔFgIlv5-4 was more sensitive to osmotic and oxidative stresses than the wild-type strain. In addition, virulence of ΔFgIlv5-4 was dramatically reduced on wheat heads, and a low level of deoxynivalenol production was detected in ΔFgIlv5-4 in wheat kernels. The results of this study indicate that FgIlv5 is involved in valine and isoleucine biosynthesis and is required for full virulence in F. graminearum.
Key Laboratory of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base/Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality (Nanjing), Ministry of Agriculture/Institute of Food Quality and Safety, Jiangsu Academy of Agricultural Sciences, 210014, Nanjing, PR China.
Xin
X
Liu
Key Laboratory of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base/Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality (Nanjing), Ministry of Agriculture/Institute of Food Quality and Safety, Jiangsu Academy of Agricultural Sciences, 210014, Nanjing, PR China.
Jian
J
Wang
Key Laboratory of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base/Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality (Nanjing), Ministry of Agriculture/Institute of Food Quality and Safety, Jiangsu Academy of Agricultural Sciences, 210014, Nanjing, PR China.
Jianhong
J
Xu
Key Laboratory of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base/Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality (Nanjing), Ministry of Agriculture/Institute of Food Quality and Safety, Jiangsu Academy of Agricultural Sciences, 210014, Nanjing, PR China.
Jianrong
J
Shi
D000597:Amino Acids, Branched-Chain / Q000096:biosynthesis*; D003470:Culture Media / Q000737:chemistry; D005670:Fusarium / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D017353:Gene Deletion; D025301:Hyphae / Q000254:growth & development; D050540:Ketol-Acid Reductoisomerase / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D010860:Pigments, Biological / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D013172:Spores, Fungal / Q000254:growth & development; D014908:Triticum / Q000382:microbiology; D014774:Virulence
D000597:Amino Acids, Branched-Chain; D003470:Culture Media; D024101:Mitochondrial Proteins; D010860:Pigments, Biological; D050540:Ketol-Acid Reductoisomerase