Mechanism of resistance to carpropamid in Magnaporthe grisea.
The inhibitory activity of carpropamid on scytalone dehydratase (SDH) extracted from a carpropamid-resistant strain of Magnaporthe grisea (Hebert) Barr was dramatically reduced in comparison with that on SDH extracted from the sensitive strain. A single-point mutation (G to A) located at the upstream region (233 bp downstream from the ATG codon) resulting in a one-amino-acid substitution (valine [GTG] 75 to methionine [ATG]: V75M) was found in the resistant strain. To examine whether the V75M mutation is the primary reason for decreasing the sensitivity of SDH to carpropamid, the SDH cDNAs of both the sensitive and the resistant strain were cloned into a GST-fused protein expression vector-system. The recombinant SDHs of both strains exhibited the same sensitivities to carpropamid as those extracted from the mycelia of the respective strains. These data clearly revealed that the V75M mutation causes the low sensitivities of the SDHs of the carpropamid-resistant strains, and strongly suggests that the V75M mutation confers resistance of these strains to carpropamid.
Takagaki
Makiichi
M
Kumiai Chemical Industry Co Ltd, Life Science Research Institute, 3360 Kamo, Kikugawa, Shizuoka 439-0031, Japan. m-takagaki@kumiai-chem.co.jp
Kaku
Koichiro
K
Watanabe
Satoshi
S
Kawai
Kiyoshi
K
Shimizu
Tsutomu
T
Sawada
Haruko
H
Kumakura
Kazuo
K
Nagayama
Kozo
K
D000577:Amides / Q000378:metabolism* / Q000633:toxicity; D001483:Base Sequence; D003001:Cloning, Molecular; D003521:Cyclopropanes / Q000378:metabolism* / Q000633:toxicity; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004351:Drug Resistance / Q000187:drug effects; D005659:Fungicides, Industrial / Q000378:metabolism* / Q000633:toxicity; D006836:Hydro-Lyases / Q000235:genetics* / Q000378:metabolism; D020082:Magnaporthe / Q000187:drug effects / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D021141:Nucleic Acid Amplification Techniques; D012275:Oryza / Q000382:microbiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid
D000577:Amides; D003521:Cyclopropanes; D018076:DNA, Complementary; D005659:Fungicides, Industrial; D006836:Hydro-Lyases; C082741:scytalone dehydratase; C113565:carpropamid