Disruption of the chitin synthase gene CHS1 from Fusarium asiaticum results in an altered structure of cell walls and reduced virulence.
Natural resistance of wheat against Fusarium head blight (FHB) is inadequate and new strategies for controlling the disease are required. Chitin synthases that catalyze chitin biosynthesis would be an ideal target for antifungal agents. In this study, a class I chitin synthase gene (CHS1) from Fusarium asiaticum, the predominant species of FHB pathogens on wheat in China, was functionally disrupted via Agrobacterium tumefaciens-mediated transformation. Specific disruption of the CHS1 gene resulted in a 58% reduction of chitin synthase activity, accompanied by decreases of 35% in chitin content, 22% in conidiation, and 16% in macroconidium length. The Deltachs1 mutant strain had a growth rate comparable to that of the wild-type on PDA medium but had a 35% increase in the number of nuclear cellulae and exhibited a remarkably increased sensitivity to osmosis stresses. Electron microscopy revealed substantial changes occurring in cell wall structures of the macroconidium, ascospore, and mycelium, with the most profound changes in the mycelium. Furthermore, the Deltachs1 mutant displayed significantly reduced pathogenicity on wheat spikes and seedlings. Re-introduction of a functional CHS1 gene into the Deltachs1 mutant strain restored the wild-type phenotype. These results reveal an important in vivo role played by a CHS1 gene in a FHB pathogen whose mycelial chitin could serve as a target for controlling the disease.
Xu
Yu-Bin
YB
Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan, PR China.
Li
He-Ping
HP
Zhang
Jing-Bo
JB
Song
Bo
B
Chen
Fang-Fang
FF
Duan
Xiao-Jun
XJ
Xu
Huai-Qian
HQ
Liao
Yu-Cai
YC
D000595:Amino Acid Sequence; D000908:Antibodies, Fungal / Q000032:analysis / Q000235:genetics; D002473:Cell Wall / Q000648:ultrastructure*; D002681:China; D002686:Chitin / Q000032:analysis; D002687:Chitin Synthase / Q000235:genetics* / Q000378:metabolism; D004271:DNA, Fungal / Q000032:analysis; D005656:Fungal Proteins / Q000032:analysis / Q000235:genetics; D005670:Fusarium / Q000235:genetics / Q000472:pathogenicity* / Q000648:ultrastructure; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D005818:Genetic Engineering / Q000379:methods; D005964:Glucosyltransferases / Q000032:analysis / Q000235:genetics; D009154:Mutation; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000235:genetics; D013172:Spores, Fungal / Q000235:genetics / Q000378:metabolism; D014908:Triticum / Q000382:microbiology; D014774:Virulence / Q000235:genetics
D000908:Antibodies, Fungal; D004271:DNA, Fungal; D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D002686:Chitin; D005964:Glucosyltransferases; D002687:Chitin Synthase