Simultaneous Transfer of Leaf Rust and Powdery Mildew Resistance Genes from Hexaploid Triticale Cultivar Sorento into Bread Wheat

Abstract

Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, and wheat leaf rust, caused by Puccinia triticina Eriks, are two important diseases that severely threaten wheat production. Sorento, a hexaploid triticale cultivar from Poland, shows high resistance to the wheat powdery mildew isolate E09 and the leaf rust isolate PHT in Beijing, China. To introduce resistance genes into common wheat, Sorento was crossed with wheat line Xuezao, which is susceptible to both diseases, and the F1 hybrids were then backcrossed with Xuezao as the recurrent male parent. By marker analysis, we demonstrate that the long arm of the 2R (2RL) chromosome confers resistance to both the leaf rust and powdery mildew isolates at adult-plant and seedling stages, while the long arm of 4R (4RL) confers resistance only to powdery mildew at both stages. The chromosomal composition of BC2F3 plants containing 2R or 2RL and 4R or 4RL in the form of substitution and translocation were confirmed by GISH (genomic in situ hybridization) and FISH (fluorescence in situ hybridization). Monosomic and disomic substitutions of a wheat chromosome with chromosome 2R or 4R, as well as one 4RS-4DL/4DS-4RL reciprocal translocation homozigote and one 2RL-1DL translocation hemizigote, were recovered. Such germplasms are of great value in wheat improvement.

Mechanisms of powdery mildew resistance of wheat – a review of molecular breeding

“…Thus cross‐species breeding by reintroducing disease resistance genes from wheat relatives is valuable for breeding more resilient cultivars. Rye and Dasypyrum villosum , close and wild relatives of common wheat, respectively, have been used for transmitting a variety of resistance genes, especially against powdery mildew and rust fungi (Graybosch, 2001; Chen et al , 2013; Li et al , 2018). For example, genes for resistance to powdery mildew ( Pm8 and Pm17 ) and rust ( Sr31 , Lr26 , and Yr9 ) on chromosome 1RS of rye have been successfully introduced into commercial wheat cultivars (Jiang et al , 1994; Kim et al , 2004).…”

Molecular Cytogenetic Identification of a New Wheat-Rye 6R Addition Line and Physical Localization of Its Powdery Mildew Resistance Gene

“…Octoploid triticale (× Triticosecale Wittmack, 2n = 8x = 56, AABBDDRR) is synthesized artificially through distant hybridization between common wheat and rye. It possesses multiple resistance genes to wheat disease and can be more easily crossed with wheat than rye, thus can be used as an alternative source in wheat improvement ( Oettler et al, 2005 ; Li et al, 2018 ). In the present study, after many years of selection of disease resistance and satisfactory agronomic traits, a stable wheat-rye 6R derivative line YT2 with high resistance to powdery mildew at the adult plant stage was obtained.…”

Development of diagnostic SNP markers for identification of rye 1RS translocations in wheat

“…Later, the USDA Central Small Grain Genotyping Laboratory at Manhattan, KS developed a new 1RS‐specific SSR marker, TSM0120 (Graybosch et al., 2019) to replace SCM0009; thus, TSM0120 currently is the more frequently used marker for 1RS in most U.S. genotyping laboratories. In addition, some STS markers were also reported for 1RS translocation, but none of them have been used in routine screening of breeding materials (Li et al., 2018; Rasheed et al., 2016; Saal & Wricke, 1999). Most of these SSR and STS markers are not suitable for large‐scale screening in wheat breeding programs because they are mainly dominant and low‐throughput gel‐based markers.…”