The potential of hybrid breeding to enhance leaf rust and stripe rust resistance in wheat

Ulrike Beukert,Jochen C Reif,Martin Ganal,Frank Ordon,Guozheng Liu,Patrick Thorwarth,Philipp H G Boeven,Yusheng Zhao,C Friedrich H Longin,Albrecht Serfling

doi:10.1007/s00122-020-03588-y

Abstract

Key messageHybrid wheat breeding is a promising strategy to improve the level of leaf rust and stripe rust resistance in wheat.Leaf rust and stripe rust belong to the most important fungal diseases in wheat production. Due to a dynamic development of new virulent races, epidemics appear in high frequency and causes significant losses in grain yield and quality. Therefore, research is needed to develop strategies to breed wheat varieties carrying highly efficient resistances. Stacking of dominant resistance genes through hybrid breeding is such an approach. Within this study, we investigated the genetic architecture of leaf rust and stripe rust resistance of 1750 wheat hybrids and their 230 parental lines using a genome-wide association study. We observed on average a lower rust susceptibility for hybrids in comparison to their parental inbred lines and some hybrids outperformed their better parent with up to 56%. Marker-trait associations were identified on chromosome 3D and 4A for leaf rust and on chromosome 2A, 2B, and 6A for stripe rust resistance by using a genome-wide association study with a Bonferroni-corrected threshold of P < 0.10. Detected loci on chromosomes 4A and 2A were located within previously reported genomic regions affecting leaf rust and stripe rust resistance, respectively. The degree of dominance was for most associations favorable in the direction of improved resistance. Thus, resistance can be increased in hybrid wheat breeding by fixing complementary leaf rust and stripe rust resistance genes with desired dominance effects in opposite parental pools.

Highlights

Wheat (Triticum aestivum L.) is an important crop in the world with an annual production of ~ 770 million tons harvested on ~ 220 million hectares in 2017 (FAO 2019)
Leaf rust caused by Puccinia triticina and stripe rust caused by Puccinia striiformis f. sp. tritici belong to the most important fungal diseases of wheat (Huerta-Espino et al 2011; Wellings 2011)
Epidemics appear in high frequency resulting in yield losses up to 70% (Chen 2005; Huerta-Espino et al 2011) as well as a reduced grain quality (Prescott et al 1986)

Summary

Introduction

Wheat (Triticum aestivum L.) is an important crop in the world with an annual production of ~ 770 million tons harvested on ~ 220 million hectares in 2017 (FAO 2019). Wheat is a central source of calories and proteins for human nutrition and plays an important role to feed the earths growing population (Peña-Bautista et al 2017). Leaf rust caused by Puccinia triticina and stripe rust caused by Puccinia striiformis f. Tritici belong to the most important fungal diseases of wheat (Huerta-Espino et al 2011; Wellings 2011). Leaf rust and stripe rust show enormous genetic diversity due to phases of sexual recombination within their life cycle. The naturally occurring rust population is subject of local adaption, stepwise evolution, and a high selection pressure leading to the dynamic development of new pathotypes (Bolton et al 2008; Schwessinger 2017). Epidemics appear in high frequency resulting in yield losses up to 70% (Chen 2005; Huerta-Espino et al 2011) as well as a reduced grain quality (Prescott et al 1986)

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