Meta-QTL analysis of tan spot resistance in wheat.

A total of 19 meta-QTL conferring resistance to tan spot were identified from 104 initial QTL detected in 15 previous QTL mapping studies. Tan spot, caused by the fungal pathogen Pyrenophora tritici-repentis (Ptr), is a major foliar disease worldwide in both bread wheat and durum wheat and can reduce grain yield due to reduction in photosynthetic area of leaves. Developing and growing resistant cultivars is a cost-effective and environmentally friendly approach to mitigate negative effects of the disease. Understanding the genetic basis of tan spot resistance can enhance the development of resistant cultivars. With that goal, over 100 QTL associated with resistance to tan spot induced by a variety of Ptr races and isolates have been identified from previous QTL mapping studies. Meta-QTL analysis can identify redundant QTL among various studies and reveal major QTL for targeting in marker-assisted selection applications. In this study, we performed a meta-QTL analysis of tan spot resistance using the reported QTL from 15 previous QTL mapping studies. An integrated linkage map with a total length of 4080.5 cM containing 47,309 markers was assembled from 21 individual linkage maps and three previously published consensus maps. Nineteen meta-QTL were clustered from 104 initial QTL projected on the integrated map. Three of the 19 meta-QTL located on chromosomes 2A, 3B, and 5A show large genetic effects and confer resistance to multiple races in multiple bread wheat and durum wheat mapping populations. The integration of those race-nonspecific QTL is a promising strategy to provide high and stable resistance to tan spot in wheat.