MOLECULAR MECHANISMS OF DRUG SENSITIVITY OF RICE BLAST FUNGI MAGNAPORTHE GRISEA TO TRIAZOLES IN CHINA

In the last few years resistance to azole fungicides has appeared in infected crops and has become more serious. Our aim was to analyse the reasons underlying the progressive decrease in the effectiveness of azole fungicides in controlling Magnaporthe grisea, the causal agent of rice blast. Forty-nine isolates of M. grisea were isolated from Hubei, Hunan, Jiangsu and Heilongjiang provinces in China. Their sensitivity to five sterol demethylation inhibitors, such as diniconazole, tebuconazole, triadimenol, triadimefon and propiconazole was measured. Three insensitive isolates (HM2, CY3 and CY6) and three hypersensitive isolates (CY8, YA10 and 101301) were characterised to elucidate the sensitivity mechanism to triazoles. Through a comparison of M13 fingerprinting, CYP51 sequences and expression, the results indicated that the genetic background of M. grisea isolates and CYP51 expression are conserved. However, the substitution of S312L in SRS4 of M. grisea CYP51F2 may contribute to the sensitivity difference of M. grisea to triazoles.