Genetic Relationships among Head Blight Resistant Cultivars of Wheat Assessed on the Basis of Molecular Markers

Abstract

Wheat head blight (Fusarium graminearum Schwab) can dramatically reduce grain yield and quality. Breeding for resistance is an effective measure of disease control. Wheat (Triticum aestivum L.) cultivars with various levels of Type II resistance have been reported worldwide; however, the genetic relationships among the cultivars with different origins are not well characterized. Sixty-five wheat cultivars from eight countries varying in head blight resistance levels were evaluated for Type II resistance and for genetic diversity on the basis of 322 amplified fragment length polymorphism (AFLP) and 19 simple sequence repeat (SSR) marker alleles. Cluster analysis using AFLP and SSR markers indicated that two Japanese landraces and most of the cultivars that relate to 'Ning 7840' aarry the Ning 7840 marker alleles that are tightly linked to the major quantitative trait locus (QTL) on chromosome 3BS. However, banding patterns of the markers linked to the major QTL in Ning 7840 were different from most of the Chinese landraces and those that originated from countries other than China and Japan. DNA fingerprinting data suggested that Chinese landrace Taiwan Wheat may be the donor of the QTL on chromosome 3BS. Combining the major QTL from Ning 7840 and other sources may facilitate pyramiding of different QTL. Cluster analysis and principal coordinate analysis (PCA) based on AFLPs and SSRs provided the best estimate of genetic relationships among wheat accessions studied. The result indicates that U.S. cultivars are more closely related to cultivars from Europe and Argentina than cultivars from Asia; therefore, integrating head blight resistance QTL from Asian sources into US wheat may increase the genetic diversity in U.S. wheat.