DETERMINATION OF THE MUTATION FREQUENCY IN A TILLING POPULATION OF THE HIGHLY FUSARIUM HEAD BLIGHT RESISTANT WHEAT LINE CM82036

摘要

Cereals are the most important sources of plant food for humans and livestock. As a result, the understanding of the genetics of resistance/susceptibility of wheat to pathogens is of great value for plant breeding purposes. Fusarium head blight (FHB)is one of the most devastating fungal diseases of wheat worldwide. For functional validation of candidate genes for FHB resistance a TILLING (Targeting Induced Local Lesions in Genomes) population of the highly FHB resistant spring wheat line CM-82036 was generated. The current study intends to determine the mutation frequency in the TILLING population of CM-82036 by screening the waxy gene Wx-Al for mutations. About 100,000 seeds of CM-82036 were treated with the chemical mutagen ethylmethane sulfonate(EMS) using two concentrations (0.053 and 0.058 mol/l) and from approximately 12,000 surviving Ml plants one head per plant was harvested. To create the M2 population 4,880 M2 seeds (one seed per head), preferably those exposed to the higher EMS concentration, were sown in the greenhouse. Subsequently, the DNA of 760 M2 plants, 380 M2 plants per EMS concentration, was extracted and analyzed in pools of four. Two gene specific primer pairs, Wx7A2 and Wx7A3, were used to identify single base mutations ina 1,205 bp fragment of the waxy gene Wx-Al by Endo-l-mediated heteroduplex cleavage. Mutations identified in the four-way pools were confirmed in individual samples. In total 20 mutations were detected by screening a total sequence of 915,800 bp. The mutation frequencies for the two different EMS concentrations were calculated: for samples treated by 0.053M EMS concentration it was one mutation per 57.23 kb, while for 0.058M EMS concentration one mutation per 38.15 kb was identified. These results arein a similar range as detected by other studies in hexaploid wheat varying from one mutation per 24 kb to one per 84 kb. The results indicate that this mutant population represents a useful resource for the wheat research community, especially for validating candidate genes for FHB resistance.