occurrence of deoxynivalenol producing isolates of fusarium graminearum species complex associated with head blight of wheat in moghan area

the severe epidemics of fusarium head blight (fhb) as a devastating disease of cereal crops has occurred on wheat in north and northwest iran in recent years. the in vitro production of deoxynivalenol (don) was qualitatively evaluated in 41 fusarium isolates collected from wheat heads associated with the scab disease, in moghan area/northwest iran. infected wheat heads were collected during 2004-2007. the isolation of causal agents was carried out using standard methods. according to morphological characteristics and using valid descriptions, all isolates belonged to fusarium graminearum species complex and f. culmorum of which the former was dominant. in order to evaluate the potential of don production in isolates, this mycotoxin was extracted and qualitatively examined by tlc method. the quantification of don was achieved using hplc method. tlc results indicated that 54.5% of studied isolates produced don but there was no significant relationship between this property and cultivars or sub-regions or years. also based on hplc analysis, maximum content of don was detected in f. graminearum isolated from cv. izen green from moghan agro-industry company fields in 2004 at the rate of 5827.11 µgkg-1. the results of present study show that don mycotoxin is produced at various contents by f. graminearum isolates on different cultivars and from different origins/ years. since don plays a role in pathogenesis and is of paramount importance in contamination of wheat grains, these results give a better insight into the significance of this disease in northwest iran.