Population genetic analysis of Fusarium asiaticum populations from barley suggest a recent shift favoring 3ADON producers in southern Chin
Zhang, H. ; Zhang, Z. ; Lee, T.A.J. van der; Xu, J. ; Xu, J.S. ; Yang, L. ; Yu, D. ; Waalwijk, C. ; Feng, J. - \ 2010
Phytopathology 100 (2010)4. - ISSN 0031-949X - p. 328 - 336.
head blight pathogen - gibberella-zeae - graminearum clade - united-states - wheat scab - chemotypes - diversity - deoxynivalenol - culmorum - markers
Fusarium asiaticum is the predominant causal agent of Fusarium head blight (FHB) in southern China. The genetic diversity was assessed by analyzing 448 single-spore F. asiaticum isolates from 18 sampling sites that were 10 to 2,000 km apart, using seven highly informative variable number of tandem repeat (VNTR) markers. This analysis showed a significant degree of population subdivision (P <0.001) among populations from upper, middle, and lower valleys of the Yangtze River, with little gene flow (Nm = 1.210). We observed a strong association between this genetic population subdivision and the mycotoxin produced. Our results show that the dramatic cline in trichothecene chemotypes may be explained by a recent and significant invasion of 3-acetyldeoxynivalenol (3ADON) producers in FHB pathogen composition in the middle valley. Using Bayesian statistics, we found a biased gene flow from 3ADON to nivalenol (NIV) populations. In addition, we observed significant genetic differentiation and linkage disequilibrium between NIV- and 3ADON-producing isolates at the same sampling sites. The impact of the changed agronomy and trade of cereal commodities on the spread of the new Fusarium population and the consequent increase of FHB observed in southern China are discussed.
Fusarium populations on Chinese barley show a dramatic gradient in mycotoxin profiles
Yang, L.J. ; Lee, T.A.J. van der; Yang, X.J. ; Yu, D.Z. ; Waalwijk, C. - \ 2008
Phytopathology 98 (2008)6. - ISSN 0031-949X - p. 719 - 727.
small-grain cereals - head blight - nivalenol-chemotypes - pcr assay - gibberella-zeae - wheat scab - ear blight - graminearum - deoxynivalenol - culmorum
We report on a large gene bank of Fusarium isolates established by a broad survey conducted in 2005 in which infected barley ears were collected in 23 counties of seven provinces and two municipalities along the Yangtze River in China. In total, 1,894 single spore isolates were obtained. The isolates were characterized at the species level by a newly developed and robust set of diagnostic primers based on single nucleotide polymorphisms (SNPs) among members of the F. graminearum clade. In addition, we determined their chemotype using previously described polymerase chain reaction (PCR) primers. The results showed that in all regions F. asiaticum was the predominant species causing Fusarium head blight (FHB) on barley in China (N = 1,706), while in the upper valleys of the Yangtze River also F. graminearum sensu stricto, F. meridionale, and F. proliferatum were found. Major differences in the chemotypes were found in the F. asiaticum populations, from very high to exclusive nivalenol (NIV) chemotypes in the mountainous upper valleys of the Yangtze River to predominantly deoxynivalenol (DON) chemotypes in the middle and lower valleys. In contrast to the F. asiaticum isolates from three counties in Sichuan province, which were largely NIV producers (278 of 291), F. graminearum isolates from these sampling sites were for the vast majority (27 of 28) DON producers, indicating that despite sharing the same habitat, these sympatric species apparently have unique mycotoxin chemotypes.