QTLs associated with resistance to chlorosis induction by Pyrenophora tritici-repentis in adult wheat

The number of genes conditioning resistance in adult wheat plants to the in duction of chlorosis by Pyrenophora tritici-repentis was estimated with mol ecular markers. Wheat plants from a segregating population of 112 recombina nt inbred Lines derived from the cross of the synthetic hexaploid W-7984 wi th Opata 85 were inoculated at anthesis with race 1 isolate Pti2. The inocu lated flag leaves were rated on a scale of 1 to 5 based on infection type. An RFLP map consisting of 542 markers was employed to identify significant associations (P<0.01) between marker loci and adult tan spot resistance. Al l of the markers were subjected to multiple regression analysis using the c omputer program qGene to determine the regression model that gave the large st R-2 value at the P<0.01 level of probability. The multiple regression mo del included five significant unlinked markers and one significant interact ion. The model gave an R-2 value of which accounted for 48.8% of the variat ion for resistance to P. tritici repentis isolate Pti2 in adult wheat plant s of this population. The major QTL identified in adults was associated wit h the locus identified by the RFLP marker XGli1 located on chromosome 1AS a nd accounted for 26.1% of the variation for resistance. This is. the same m arker found to be associated with the QTL QTsc.ndsu-1A in seedlings of this population.