Progress in breeding for resistance to Ug99 and other races of the stem rust fungus in CIMMYT wheat germplasm

Bhavani, Sridhar; Hodson, David; Espino, Julio Huerta; Randhawa, M. S.; Singh, Ravi P.

doi:10.15302/j-fase-2019268

Cited by 42 publications

(36 citation statements)

References 73 publications

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“…Stem rust can cause greater damage when susceptible wheat cultivars are grown over wide geographical regions and early infections may lead to large scale epidemics in a short period ( Bhavani et al., 2019 ). Severe stem rust pressure can affect tillering ( Rowell and Roelfs, 1976 ), plant growth by reducing the photosynthetic area, nutrients and water supply, and their transportation in the plant system ( Roelfs, 1985 ).…”

Section: Wheat Rust Diseases and Their Impact On Productivitymentioning

confidence: 99%

Application of Genomics Tools in Wheat Breeding to Attain Durable Rust Resistance

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Section: Wheat Rust Diseases and Their Impact On Productivitymentioning

confidence: 99%

Application of Genomics Tools in Wheat Breeding to Attain Durable Rust Resistance

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“…East African highlands are considered as hot spots for the emergence of new stem rust pathogen races. The emergence of new virulent races in East Africa and other parts of the world caused severe losses and continue to pose a threat to global wheat production and food security ( Olivera et al, 2015 ; Singh et al, 2015 ; Bhavani et al, 2019 ). Many of the races evolve with corresponding virulence to commercially deployed resistance genes and some have broad virulence spectrum.…”

Section: Introductionmentioning

confidence: 99%

“…Stem rust race Ug99 was identified in Uganda in 1999 and spread across other countries in East Africa, the Middle East and South Africa. To date, 13 races identified from different countries with broad virulence to commercially deployed resistance genes, are considered part of the of the Ug99 lineage ( Singh et al, 2015 ; Nirmala et al, 2017 ; Bhavani et al, 2019 ). Due to the continuously evolving races in the Ug99 group, most of the worldwide wheat germplasm were found to be moderately to highly susceptible to this group of races ( Bajgain et al, 2015b ; Singh et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Multiple-Race Stem Rust Resistance Loci Identified in Durum Wheat Using Genome-Wide Association Mapping

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Stem rust of wheat caused by Puccinia graminis Pers. f.sp. trtici Eriks and E. Henn., is the most damaging fungal disease of both common (Triticum aestivum L.) and durum (Triticum turgidum L., ssp. Durum) wheat. Continuously emerging races virulent to many of the commercially deployed qualitative resistance genes have caused remarkable loss worldwide and threaten global wheat production. The objectives of this study were to evaluate the response of a panel of 283 durum wheat lines assembled by the International Maize and Wheat Improvement Center (CIMMYT) to multiple races of stem rust in East Africa at the adult plant stage and map loci associated with field resistance. The lines were evaluated in Debre Zeit, Ethiopia and Njoro, Kenya from 2018 to 2019 in five environments (year × season). The panel was genotyped using genotyping-by-sequencing. After filtering, 26,439 Single Nucleotide Polymorphism (SNP) markers and 280 lines and three checks were retained for analysis. Population structure was assessed using principal component analysis. Genome-wide association analysis (GWAS) was conducted using Genomic Association and Prediction Integrated Tool (GAPIT). The broad-sense heritability of the phenotype data revealed that 64–83% of the variation in stem rust response explained by the genotypes and lines with multiple race resistance were identified. GWAS analysis detected a total of 160 significant marker trait associations representing 42 quantitative trait loci. Of those, 21 were potentially novel and 21 were mapped to the same regions as previously reported loci. Known stem rust resistance genes/alleles were postulated including Sr8a, Sr8155B1, SrWeb/Sr9h, Sr11, Sr12, Sr13/Sr13 alleles, Sr17, Sr28/Sr16, Sr22, and Sr49. Lines resistant to multiple races in East Africa can be utilized as parents in durum wheat breeding programs. Further studies are needed to determine if there are new alleles at the Sr13 locus and potential markers for the known Sr13 alleles.

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“…This includes the Ug99 race (TTKSK) which was first discovered in Uganda in 1998 (Pretorius et al 2000;Singh et al 2011) and was virulent to most of the stem rust resistance genes deployed in global wheat germplasm at that time. About four additional variants of Ug99 each with increasing virulence to more stem rust resistance genes and five new non-Ug99 races have since been reported in Kenya and Ethiopia (Singh et al 2015;Bhavani et al 2019). Sr26, a gene introgressed from Agropyron elongatum (Liu et al 2010), is one of very few resistance genes still effective against all known Ug99 variants.…”

Section: Discussionmentioning

confidence: 99%

Allelic diversity study of functional genes in East Africa bread wheat highlights opportunities for genetic improvement

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Wheat (Triticum aestivum L.) is a major staple crop in East Africa (EA) providing 9% and 10% of daily calories and protein intake, respectively. However, EA countries depend on import to meet 55% of their domestic wheat supplies due to increasing demands and low domestic yields. To determine the beneficial gene pool currently exploited for wheat improvement in EA, we examined the allelic diversity of 39 genes of breeding importance in a collection of 239 wheat cultivars and breeding lines from Kenya and Ethiopia using KASP markers. The assayed genes have been shown to control variations in plant height, thousand kernel weight (TKW), grain protein content, pre-harvest sprouting (PHS), disease resistance, and flowering time. We observed the beneficial alleles of some major genes including Gpc-B1, Yr5, Yr15, Sr26, and Fhb1 to be missing or present at low frequencies in this population. Furthermore, we validated the effects of the major Rht-1 alleles and TaCKX-D1 in controlling variation in plant height and thousand kernel weight, respectively, under EA conditions. Our results uncover hitherto unexploited allelic diversity that can be used to improve the genetic potential of EA wheat germplasm. This will inform strategies to rapidly mobilize these beneficial alleles for wheat improvement in EA.

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Progress in breeding for resistance to Ug99 and other races of the stem rust fungus in CIMMYT wheat germplasm

Abstract: Races belonging to the Ug99 (TTKSK) lineage of the wheat stem rust fungus, carrying complex virulence combinations,

Cited by 42 publications

References 73 publications

Application of Genomics Tools in Wheat Breeding to Attain Durable Rust Resistance

Application of Genomics Tools in Wheat Breeding to Attain Durable Rust Resistance

Multiple-Race Stem Rust Resistance Loci Identified in Durum Wheat Using Genome-Wide Association Mapping

Allelic diversity study of functional genes in East Africa bread wheat highlights opportunities for genetic improvement

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