Detection and dynamics of different carbendazim-resistance conferring β-tubulin variants of Gibberella zeae collected from infected wheat heads and rice stubble in China.

BACKGROUND: Carbendazim has been used in the control of Fusarium head blight (FHB) for more than 30 years in China. Thus, carbendazim-resistant (Car(R) ) populations of Gibberella zeae have developed in some areas. In this study, 9341 G. zeae isolates were collected from the ten main wheat-producing regions of China in the period from 2008 to 2012, and sensitivity to carbendazim was detected.
RESULTS: A high frequency of Car(R) isolates was observed in Zhejiang and Jiangsu provinces. Car(R) isolates were recovered from Anhui and Henan provinces in 2009 and 2012, respectively, but were not detected in the other six regions. Available (F167Y, E198Q and F200Y) and newly developed (E198L and E198K) allele-specific PCR assays were used to genotype field Car(R) isolates. The β-tubulin variants harbouring point mutation F167Y or E198Q accounted for >95% in Car(R) populations. Quantitative allele-specific real-time PCR assays were developed to determine the frequencies of five different β-tubulin variants present in populations of perithecia sampled from rice stubble.
CONCLUSION: Car(R) populations of G. zeae develop rapidly under the selection pressure of carbendazim. Real-time PCR assays detecting the resistance frequencies in populations of perithecia would provide useful information for FHB control and management of resistance.