Powdery mildew resistance and Lr34/Yr18 genes for durable resistance to leaf and stripe rust cosegregate at a locus on the short arm of chromosome 7D of wheat

Wheat pathogens, especially those causing powdery mildew and stripe rust, seriously threaten yield worldwide. Utilizing newly identified disease resistance genes from wheat relatives is an effective strategy to minimize disease damage. In this study, chromosome-specific molecular markers for the 3Sb and 7Sb chromosomes of Aegilops bicornis were developed using PCR-based landmark unique gene (PLUG) primers for screening wheat-Ae. bicornis progenies. Fluorescence in situ hybridization (FISH) was performed to further identify wheat-Ae. bicornis progenies using oligonucleotides probes Oligo-pSc119.2-1, Oligo-pTa535-1, and Oligo-(GAA)8. After establishing Ae. bicornis 3Sb and 7Sb chromosome-specific FISH markers, Holdfast (common wheat)-Ae. bicornis 3Sb addition, 7Sb addition, 3Sb(3A) substitution, 3Sb(3B) substitution, 3Sb(3D) substitution, 7Sb(7A) substitution, and 7Sb(7B) substitution lines were identified by the molecular and cytological markers. Stripe rust and powdery mildew resistance, along with agronomic traits were investigated to evaluate the breeding potential of these lines. Holdfast and Holdfast-Ae. bicornis progenies were all highly resistant to stripe rust, indicating that the stripe rust resistance might derive from Holdfast. However, Holdfast-Ae. bicornis 3Sb addition, 3Sb(3A) substitution, 3Sb(3B) substitution, and 3Sb(3D) substitution lines showed high resistance to powdery mildew while Holdfast was highly susceptible, indicating that chromosome 3Sb of Ae. bicornis carries previously unknown powdery mildew resistance gene(s). Additionally, the transfer of the 3Sb chromosome from Ae. bicornis to wheat significantly increased tiller number, but chromosome 7Sb has a negative effect on agronomic traits. Therefore, wheat germplasm containing Ae. bicornis chromosome 3Sb has potential to contribute to improving powdery mildew resistance and tiller number during wheat breeding.

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QTL mapping for stripe rust and powdery mildew resistance in Triticum durum–Aegilops speltoides backcross introgression lines

Plant Genetic Resources ◽

10.1017/s1479262120000222 ◽

2020 ◽

Vol 18 (4) ◽

pp. 211-221

Author(s):

Guriqbal Singh Dhillon ◽

Satinder Kaur ◽

Niranjan Das ◽

Rohtas Singh ◽

Jesse Poland ◽

...

Keyword(s):

Powdery Mildew ◽

Qtl Mapping ◽

Stripe Rust ◽

Triticum Durum ◽

Powdery Mildew Resistance ◽

Introgression Lines ◽

Stripe Rust Resistance ◽

Adult Plant ◽

Aegilops Speltoides ◽

Mildew Resistance

AbstractWheat, a major food crop, faces significant yield constraints due to losses caused by various diseases, especially rusts and powdery mildew. Since the causal organisms are always evolving, there is a never-ending hunt for new genes/quantitative trait loci (QTLs) for resistance to control the damage. For this purpose, Triticum durum–Aegilops speltoides backcross introgression lines (DS-BILs) developed in our wide hybridization programme were screened against stripe rust and powdery mildew at both seedling and adult plant stages. DS-BILs showed complete to moderate resistance at the adult plant stage while varying resistance and susceptibility at the seedling stage. A total of 1095 single-nucleotide polymorphisms (SNPs) identified on 14 chromosomes of T. durum, using genotyping by sequencing, were used for QTL mapping. Eleven unique QTLs, across six chromosomes (chr1B, chr2A, chr2B, chr3B, chr6B and chr7B) were identified for resistance, four QTLs for field mixture of stripe rust pathotypes, two QTLs for stripe rust pathotype 78S84 and five QTLs for field mixture of powdery mildew pathotypes using stepwise regression-based likelihood ratio test for additive effect of markers and single-marker analysis. Eleven DS-BILs carrying multiple QTLs were identified which will serve as a useful resource to transfer the respective resistance to susceptible cultivars to develop all stage resistant elite cultivars where QTL for stripe rust resistance QYrAs.pau-2A.1 (LOD 3.8, PVE 24.51 linked to SNP S2A_16016633) and QTL for powdery mildew resistance QPmAs.pau-6B (logarithm of the odds (LOD) 3.2, phenotypic variation explained (PVE) 17.75 linked to SNP S6B_26793381) are major targets of the transfer.

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Evaluation of Resistance to Powdery Mildew in Triticale Seedlings and Adult Plants

Plant Disease ◽

10.1094/pdis-02-12-0161-re ◽

2013 ◽

Vol 97 (3) ◽

pp. 410-417 ◽

Cited By ~ 8

Author(s):

V. Troch ◽

K. Audenaert ◽

A. Vanheule ◽

B. Bekaert ◽

M. Höfte ◽

...

Keyword(s):

Powdery Mildew ◽

Plant Growth ◽

Resistance Genes ◽

Powdery Mildew Resistance ◽

Quantitative Resistance ◽

Durable Resistance ◽

Adult Plant ◽

Growth Stages ◽

Mildew Resistance ◽

Plant Growth Stages

Triticale (×Triticosecale) is the intergeneric hybrid between the female parent wheat and the male parent rye. With the expansion of the triticale growing area, powdery mildew emerged on this new host and has become a significant disease on triticale. Recent research demonstrated that this “new” powdery mildew on triticale has emerged through a host range expansion of powdery mildew of wheat. Moreover, this expansion occurred recently and multiple times at different locations in Europe. An effective and environmentally sensitive approach to controlling powdery mildew involves breeding crop plants for resistance. The main goal of this study was to identify the presence of powdery mildew resistance in commercial triticale cultivars. First, the avirulence (AVR) genes and gene complexity carried by this new powdery mildew population on triticale were characterized. Virulence was identified for all the resistance genes evaluated in the present study, and virulence frequencies higher than 50% were recorded on the genes Pm3f, Pm5b, Pm6, Pm7, Pm8, and Pm17. Using molecular markers, the presence of resistance genes Pm3f and Pm17 was identified in certain triticale cultivars. The triticale cultivars were also evaluated for the presence of quantitative resistance at adult plant growth stages in a 2-year field experiment. Despite the high disease pressure, cultivars highly resistant at the adult-plant growth stages were identified. Because ‘Grenado’ also showed effective race-specific resistance, this cultivar could be of high value for breeding for durable resistance to powdery mildew. Altogether, this study reveals valuable information on the presence of powdery mildew resistance in commercial triticale cultivars, which can be used in breeding programs in triticale. Additionally, this study underscores the need to broaden the base of powdery mildew resistance in triticale through introgression and deployment of new sources of mildew resistance, including quantitative resistance.

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Molecular Characterization of a Powdery Mildew Resistance Gene in Wheat Cultivar Suwon 92

Phytopathology ◽

10.1094/phyto-96-0496 ◽

2006 ◽

Vol 96 (5) ◽

pp. 496-500 ◽

Cited By ~ 10

Author(s):

X.-Y. Xu ◽

G.-H. Bai ◽

B. F. Carver ◽

G. E. Shaner ◽

R. M. Hunger

Keyword(s):

Powdery Mildew ◽

Resistance Gene ◽

Resistance Genes ◽

Powdery Mildew Resistance ◽

Durable Resistance ◽

Phenotypic Variance ◽

Powdery Mildew Resistance Gene ◽

Gene Markers ◽

Mildew Resistance ◽

Ril Population

Powdery mildew, caused by Blumeria graminis f. sp tritici, is an important foliar disease of wheat worldwide. Pyramiding race-specific genes into a single cultivar and combining race-specific resistance genes with durable resistance genes are the preferred strategies to improve the durability of powdery mildew resistance. The objectives of this study were to characterize a powdery mildew resistance gene in Suwon 92 and identify gene-specific or tightly linked molecular markers for marker-assisted selection (MAS). A population of recombinant inbred lines (RILs) was derived by single seed descent from a cross between Suwon 92 and a susceptible cultivar, CI 13227. The RILs were screened for adult-plant infection type of powdery mildew and characterized with amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers. The linked markers explained 41.3 to 69.2% of the phenotypic variances measured in 2 years. A morphological marker, hairy glume, was also associated with powdery mildew resistance in Suwon 92, and explained 43 to 51% of the phenotypic variance. The powdery mildew resistance gene in Suwon 92 was located on the short arm of chromosome 1A where Pm3 was located. Two gene-specific markers were developed based on the sequence of the cloned Pm3b gene. These two markers, which were mapped at the same locus in the peak region of the LOD score for the RIL population, explained most of the phenotypic variance for powdery mildew resistance in the RIL population. The powdery mildew resistance in Suwon 92 is most likely conditioned by the Pm3 locus. The gene markers developed herein can be directly used for MAS of some of the Pm3 alleles in breeding programs.

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