Geographic substructure of Fusarium asiaticum isolates collected from barley in China

Fusarium head blight (FHB) can affect wheat and barley and is a devastating disease caused by a complex of Fusarium species. Here we report on a large-scale survey on the genetic diversity of isolates collected from barley in China. Ten VNTR markers were tested on a representative set of 40 isolates covering 14 sampling areas along the Yangtze River. VNTR4 and VNTR7, with 13 and 6 alleles, each were applied to a total of 1106 single-spore isolates to reveal the population structure of F. asiaticum. The F. asiaticum population showed high genetic diversity and a clear genotypic substructure within China. Pair-wise comparisons of allele frequencies between the mountainous provinces of Sichuan and Chongqing in Western China, Hubei Province in the centre or the eastern provinces of Zhejiang, Jiangsu and Shanghai showed significant differences. Even between counties of the same province, significant differences between allele frequencies were found (P < 0.001). Our results indicate serious constraints for migration of this pathogen in the major cereal-growing areas of China.