Mapping of adult plant stripe rust resistance genes in diploid A genome wheat species and their transfer to bread wheat

Abstract

Stripe rust, caused by Puccinia striiformis West. f.sp. tritici, is one of the most damaging diseases of wheat worldwide. Forty genes for stripe rust resistance have been catalogued so far, but the majority of them are not effective against emerging pathotypes. Triticum monococcum and T. boeoticum have excellent levels of resistance to rusts, but so far, no stripe rust resistance gene has been identified or transferred from these species. A set of 121 RILs generated from a cross involving T. monococcum (acc. pau14087) and T. boeoticum (acc. pau5088) was screened for 3 years against a mixture of pathotypes under field conditions. The parental accessions were susceptible to all the prevalent pathotypes at the seedling stage, but resistant at the adult plant stage. Genetic analysis of the RIL population revealed the presence of two genes for stripe rust resistance, with one gene each being contributed by each of the parental lines. A linkage map with 169 SSR and RFLP loci generated from a set of 93 RILs was used for mapping these resistance genes. Based on phenotypic data for 3 years and the pooled data, two QTLs, one each in T. monococcum acc. pau14087 and T. boeoticum acc. pau5088, were detected for resistance in the RIL population. The QTL in T. monococcum mapped on chromosome 2A in a 3.6 cM interval between Xwmc407 and Xwmc170, whereas the QTL from T. boeoticum mapped on 5A in 8.9 cM interval between Xbarc151 and Xcfd12 and these were designated as QYrtm.pau-2A and QYrtb.pau-5A, respectively. Based on field data for 3 years, their R2 values were 14 and 24%, respectively. T. monococcum acc. pau14087 and three resistant RILs were crossed to hexaploid wheat cvs WL711 and PBW343, using T. durum as a bridging species with the objective of transferring these genes into hexaploid wheat. The B genome of T. durum suppressed resistance in the F1 plants, but with subsequent backcrossing one resistance gene could be transferred from one of the RILs to the hexaploid wheat background. This gene was derived from T. boeoticum acc. pau5088 as indicated by co-introgression of T. boeoticum sequences linked to stripe rust resistance QTL, QYrtb.pau-5A. Homozygous resistant progenies with 40-42 chromosomes have been identified.

Review Article: High-Temperature Adult-Plant Resistance, Key for Sustainable Control of Stripe Rust

“…In addition, adultplant resistance to stripe rust controlled by a single gene or QTL was reported in wheat genotypes "Bersee" as Yr16 [61], in "Pavon F76" as Yr29 [62], in wheat genotype "Lgst. 79 -74" as Yrns-B1 [63], in "Opata 85" as Yr30 [64], in "Cook" [65], in a T. boeoticum transgressed wheat genotype as QYrtb.pau-5A and a T. monococcum transgressed wheat line as QYrtm.pau-2A [66], and in wheat genotype "Aquileja" [21]; and by three genes or QTL was reported in "Guardian" [67]. In winter wheat "IDO444", HTAP resistance is controlled by two major QTL and three minor QTL [56].…”

Study of genetic parameters and association between characters in einkorn genotypes

“…It is very useful and promising plant breeding material for its resistance to disease (rusts, powdery mildew) (1)(2)(3)(4)(5)(6)(7)(8). The crop is suitable for low input systems -organic farmingbecause of its better adaptability in marginal areas (in comparison with other crops) (1,9).…”

Identification and mapping of two powdery mildew resistance genes in Triticum boeoticum L.

“…These introgression lines had resistance to stripe and leaf rusts (Singh et al 2007a;Chhuneja et al 2008). One of the RILs, designated as RIL101 has T. boeoticum specific alleles at both the loci PmTb7A.1 and PmTb-7A.2 but none of the introgression lines was resistant to powdery mildew when tested againt Bgt 07201 and Bgt 07302 isolates.…”

“…The RILs with powdery mildew score of 0-5% were categorized as resistant (R) and RILs with >5% PM score were classified as susceptible (S). The wheat powdery mildew isolates were used from the former mildew collections of Agroscope (Singh et al 2007a;Chhuneja et al 2008). Three of the isolates Bgt 07201, Bgt 07302 and Bgt 97011 showing differential reaction on the parental lines were selected to screen the RILs for studying the inheritance of powdery mildew resistance in the Tb5088/Tm14087 population.…”

“…pau5088 was crossed with T. monococcum accession pau14087 to generate a RIL population, which showed segregation for stripe rust, Karnal bunt and cereal cyst nematode resistance (Singh et al 2007a;Chhuneja et al 2008;Singh et al 2010). …”