عنوان مقاله [English]
نویسندگان [English]چکیده [English]
One of the most important diseases on wheat is Fusarium head blight (FHB) which causes high losses on wheat crop quantitatively and qualitatively. The main species caused FHB are Fusarium graminearum, F. culmorum and F. avenaceum. Fusarium graminearum isolates are concerned as the major agents to produce deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, nivalenol, and zeralenone in wheat. Regarding to high DON contamination of 2011 wheat crop production at Ardabil province, population analysis of the Fusarium graminearum species complex isolated from wheat crop of this area was considered as the purpose of this study. During Jun till July of 2011 the FHB wheat contaminated samples were collected from wheat fields and harvested wheat crop through Ardabil area and Fusarium isolates obtained from wheat samples using suitable laboratory methods. 321 F. graminearum isolates were identified based on morphological characters. The identification of all 321 isolates was confirmed molecularly using Nicholson's specific F. graminearum primers. To resolve the different members of the F. graminearum clade, the species specific primers which designed for partial sequences of the ammonia ligase 2 (CTPS2) gene were used. F. asiaticum, F. meridionale, and other members of the F. graminearum clade can be distinguished based on differences in the length of the CTPS2-derived amplicons by these primers. The primers for the ammonia ligase 2 gene produce fragments of 162 and 3l1bp in isolates of F. asiaticum, while the 311bp fragments are observed in all other members of the F. graminearum clade To find the phylogenic relation four isolates were selected as the representative isolates and their ammonia ligase 2 gene amplicons were sequenced. The results of PCR products showed that 89.4% of F. graminearum isolates (287 out of 321isolates) were F. asiaticum due to producing both 162 bp and 311 bp bands while in 10.6 % of isolates only one band (311 bp) was produced which indicated this minority of isolates were not F. asiaticum but they were in the clade of F. graminearum. The sequences of the ammonia ligase 2 gene amplicons of four representative isolates confirmed the identification of F. asiaticum as the dominant species of F. graminearum clade on FHB contaminated wheat in Ardebil province. The results showed that F. asiaticum was the predominant species causing Fusarium head blight (FHB) of wheat suggested resulting in DON production throughout all regions of Ardabil province.