QTL mapping of adult plant and seedling resistance to leaf rust (Puccinia triticina Eriks.) in a multiparent advanced generation intercross (MAGIC) wheat population

Sandra Rollar,Albrecht Serfling,Frank Ordon,Volker Mohler,Lorenz Hartl,Manuel Geyer

doi:10.1007/s00122-020-03657-2

Abstract

Key messageThe Bavarian MAGIC Wheat population, comprising 394 F6:8 recombinant inbred lines was phenotyped for Puccinia triticina resistance in multi-years’ field trials at three locations and in a controlled environment seedling test. Simple intervall mapping revealed 19 QTL, corresponding to 11 distinct chromosomal regions.The biotrophic rust fungus Puccinia triticina is one of the most important wheat pathogens with the potential to cause yield losses up to 70%. Growing resistant cultivars is the most cost-effective and environmentally friendly way to encounter this problem. The emergence of leaf rust races being virulent against common resistance genes increases the demand for wheat varieties with novel resistances. In the past decade, the use of complex experimental populations, like multiparent advanced generation intercross (MAGIC) populations, has risen and offers great advantages for mapping resistances. The genetic diversity of multiple parents, which has been recombined over several generations, leads to a broad phenotypic diversity, suitable for high-resolution mapping of quantitative traits. In this study, interval mapping was performed to map quantitative trait loci (QTL) for leaf rust resistance in the Bavarian MAGIC Wheat population, comprising 394 F6:8 recombinant inbred lines (RILs). Phenotypic evaluation of the RILs for adult plant resistance was carried out in field trials at three locations and two years, as well as in a controlled-environment seedling inoculation test. In total, interval mapping revealed 19 QTL, which corresponded to 11 distinct chromosomal regions controlling leaf rust resistance. Six of these regions may represent putative new QTL. Due to the elite parental material, RILs identified to be resistant to leaf rust can be easily introduced in breeding programs.

Highlights

With approximately 219 million hectares worldwide and 30% of global major cereal crop production in 2017, wheat (Triticum spp.) belongs to the most important crops for human nutrition (Braun et al 2010; FAO 2019)
Single maximal Average ordinate (AO) scores up to 63.8% were observed within the population (Table 1)
Detection of effective leaf rust resistances is of essential importance to avoid rust epidemics

Summary

Introduction

With approximately 219 million hectares worldwide and 30% of global major cereal crop production in 2017, wheat (Triticum spp.) belongs to the most important crops for human nutrition (Braun et al 2010; FAO 2019). Leaf rust, caused by the obligate biotrophic fungus Puccinia triticina Eriks., is nowadays the most destructive and prevalent rust pathogen in wheat (Kolmer 2005). Due to its adaptation to a wide range of different environments, leaf rust occurs in many wheat-producing areas of the temperate zone, causing yield losses up to 70% (Aktar-Uz-Zaman et al 2017; Herrera-Foessel et al 2006; Marasas et al 2004). The application of fungicides helps to avoid yield losses, the deployment of resistant cultivars is the most effective, economic, and environmentally friendly approach to manage this disease. Both qualitative and quantitative resistances are known. Seedling/qualitative resistance is monogenically inherited and only effective

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