Leaf scald resistance genes in Hordeum vulgare and Hordeum vulgare ssp. spontaneum: parallels between cultivated and wild barley

2003 ◽  
Vol 54 (12) ◽  
pp. 1335 ◽  
Author(s):  
R. K. Genger ◽  
K. J. Williams ◽  
H. Raman ◽  
B. J. Read ◽  
H. Wallwork ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Hordeum Vulgare ◽  
Wild Barley ◽  
Infection Type ◽  
Field Trials ◽  
Field Resistance ◽  
Adult Plant ◽  
Sources Of Resistance ◽  
Ssr Loci ◽  
Cultivated Barley

The prerequisite for breeding barley varieties with durable scald resistance is a diversity of genes each with molecular markers for their manipulation in crosses. Here we compare the outcomes of genetic analysis of scald resistance in 5 doubled haploid mapping populations of cultivated barley with 9 third-backcross families that derive from a set of diverse wild barley populations. In all cases, resistance was assessed as seedling infection type responses, but the Sloop/Halcyon population was also tested for adult plant resistance in field trials at two sites. In the latter case, the major quantitative trait locus for field resistance was coincident with that for seedling response on chromosome 3H. Most of the other cultivated barley sources of resistance in this study (1 cultivar and 3 breeders populations synthesised for resistance) also resolved to markers in the region of this 3H locus. In contrast, the genetic basis of resistance in wild barley populations resolved to at least 5 chromosome locations (1HS, 3H, 6HS, 7HL, and 7HS). Useful markers were of several kinds including proteins, isozymes, PCR based on RFLPs, AFLP, and SSR loci. Thus, wild barley increases the range of options for pyramid breeding and provides linked molecular markers that will be useful in manipulating those genes, or in the analysis of resistance in new sources.

Population genetics and phylogenetic analysis of the vrs1 nucleotide sequence in wild and cultivated barley

Genome ◽  
2014 ◽  
Vol 57 (4) ◽  
pp. 239-244 ◽  
Author(s):  
Xifeng Ren ◽  
Yonggang Wang ◽  
Songxian Yan ◽  
Dongfa Sun ◽  
Genlou Sun
Keyword(s):  
Population Genetics ◽  
Phylogenetic Analysis ◽  
Genetic Variation ◽  
Hordeum Vulgare ◽  
Nucleotide Diversity ◽  
Wild Barley ◽  
Haplotype Diversity ◽  
Lateral Spikelet ◽  
Cultivated Barley ◽  
Barley Population

Spike morphology is a key characteristic in the study of barley genetics, breeding, and domestication. Variation at the six-rowed spike 1 (vrs1) locus is sufficient to control the development and fertility of the lateral spikelet of barley. To study the genetic variation of vrs1 in wild barley (Hordeum vulgare subsp. spontaneum) and cultivated barley (Hordeum vulgare subsp. vulgare), nucleotide sequences of vrs1 were examined in 84 wild barleys (including 10 six-rowed) and 20 cultivated barleys (including 10 six-rowed) from four populations. The length of the vrs1 sequence amplified was 1536 bp. A total of 40 haplotypes were identified in the four populations. The highest nucleotide diversity, haplotype diversity, and per-site nucleotide diversity were observed in the Southwest Asian wild barley population. The nucleotide diversity, number of haplotypes, haplotype diversity, and per-site nucleotide diversity in two-rowed barley were higher than those in six-rowed barley. The phylogenetic analysis of the vrs1 sequences partially separated the six-rowed and the two-rowed barley. The six-rowed barleys were divided into four groups.

Reactions of eastern Canada oat genotypes to Puccinia coronata f. sp. avenae

2020 ◽  
Vol 100 (2) ◽  
pp. 209-217
Author(s):  
Allen G. Xue ◽  
Jim Menzies ◽  
Yuanhong Chen ◽  
Weikai Yan ◽  
Bao-luo Ma ◽  
...  
Keyword(s):  
Natural Populations ◽  
Field Trials ◽  
Crown Rust ◽  
Puccinia Coronata ◽  
Adult Plant ◽  
Limiting Factor ◽  
Sources Of Resistance ◽  
Eastern Canada ◽  
Breeding Programs ◽  
Breeding Lines

Crown rust, caused by Puccinia coronata f. sp. avenae (Pca), is the most important disease and yield limiting factor of oat production in eastern Canada. In this study 101 oat genotypes composed of 51 cultivars and 50 breeding lines from eight oat breeding programs across Canada were evaluated for seedling reactions to six common Pca races, as well as reactions to a bulk inoculum of Pca in greenhouse trials and for adult plant resistance (APR) to natural populations of Pca in field trials in 2014 and 2015. Sixty-six genotypes showed resistant reactions to at least one of the six races; of these, 22 were resistant to all six races. These 22 genotypes also showed resistance to the bulk inoculum at the seeding stage and to the natural populations of Pca at the adult plant stage, suggesting that these current and future oat varieties have effective resistance against the common races and Pca populations in the region. Eleven genotypes, including 12ANS03, AAC Bullet, CFA1213, CFA1306, Idaho, OA1301-1w-3, OA1369-5, OA1370-2, OA1371-2, OA1383-2, and Oscar, were susceptible as seedlings but resistant as adult plants. APR is proven to be long lasting and provides broad-spectrum resistance to Pca populations. The 11 oat genotypes identified with APR in the present study are more desirable as sources of resistance for breeding programs developing durable crown rust resistant cultivars for eastern Canada.

scholarly journals Vulnerability of Barley to African Pathotypes of Puccinia graminis f. sp. tritici and Sources of Resistance

2017 ◽  
Vol 107 (8) ◽  
pp. 950-962 ◽  
Author(s):  
B. J. Steffenson ◽  
A. J. Case ◽  
Z. A. Pretorius ◽  
V. Coetzee ◽  
F. J. Kloppers ◽  
...  
Keyword(s):  
Resistance Genes ◽  
High Frequency ◽  
Wild Barley ◽  
Durable Resistance ◽  
Global Scale ◽  
Puccinia Graminis ◽  
Wild Progenitor ◽  
Sources Of Resistance ◽  
Cultivated Barley ◽  
Moderately Resistant

The emergence of widely virulent pathotypes (e.g., TTKSK in the Ug99 race group) of the stem rust pathogen (Puccinia graminis f. sp. tritici) in Africa threatens wheat production on a global scale. Although intensive research efforts have been advanced to address this threat in wheat, few studies have been conducted on barley, even though pathotypes such as TTKSK are known to attack the crop. The main objectives of this study were to assess the vulnerability of barley to pathotype TTKSK and identify possible sources of resistance. From seedling evaluations of more than 1,924 diverse cultivated barley accessions to pathotype TTKSK, more than 95% (1,844) were found susceptible. A similar high frequency (910 of 934 = 97.4%) of susceptibility was found for the wild progenitor (Hordeum vulgare subsp. spontaneum) of cultivated barley. Additionally, 55 barley lines with characterized or putative introgressions from various wild Hordeum spp. were also tested against pathotype TTKSK but none was found resistant. In total, more than 96% of the 2,913 Hordeum accessions tested were susceptible as seedlings, indicating the extreme vulnerability of the crop to the African pathotypes of P. graminis f. sp. tritici. In total, 32 (1.7% of accessions evaluated) and 13 (1.4%) cultivated and wild barley accessions, respectively, exhibited consistently highly resistant to moderately resistant reactions across all experiments. Molecular assays were conducted on these resistant accessions to determine whether they carried rpg4/Rpg5, the only gene complex known to be highly effective against pathotype TTKSK in barley. Twelve of the 32 (37.5%) resistant cultivated accessions and 11 of the 13 (84.6%) resistant wild barley accessions tested positive for a functional Rpg5 gene, highlighting the narrow genetic base of resistance in Hordeum spp. Other resistant accessions lacking the rpg4/Rpg5 complex were discovered in the evaluated germplasm and may possess useful resistance genes. Combining rpg4/Rpg5 with resistance genes from these other sources should provide more durable resistance against the array of different virulence types in the Ug99 race group.

scholarly journals Sources of Resistance to Stem Rust Race Ug99 in Spring Wheat Germplasm

Plant Disease ◽  
2011 ◽  
Vol 95 (6) ◽  
pp. 762-766 ◽  
Author(s):  
M. N. Rouse ◽  
R. Wanyera ◽  
P. Njau ◽  
Y. Jin
Keyword(s):  
Spring Wheat ◽  
Resistance Genes ◽  
North American ◽  
Stem Rust ◽  
Wheat Breeding ◽  
Field Resistance ◽  
Eastern Africa ◽  
Adult Plant ◽  
Sources Of Resistance ◽  
Wheat Stem Rust

Wheat stem rust (Puccinia graminis f. sp. tritici) race TTKSK (Ug99), with virulence to the majority of the world's wheat (Triticum aestivum) cultivars, has spread from Uganda throughout eastern Africa, Yemen, and Iran. The identification and spread of variants of race TTKSK with virulence to additional stem rust resistance genes has reminded breeders and pathologists of the danger of deploying major resistance genes alone. In order to protect wheat from this rapidly spreading and adapting pathogen, multiple resistance genes are needed, preferably from improved germplasm. Preliminary screening of over 700 spring wheat breeding lines and cultivars developed at least 20 years ago identified 88 accessions with field resistance to Ug99. We included these resistant accessions in the stem rust screening nursery in Njoro, Kenya for two additional seasons. The accessions were also screened with a bulk of North American isolates of P. graminis f. sp. tritici in the field in St. Paul, MN. In order to further characterize the resistance in these accessions, we obtained seedling phenotypes for 10 races of P. graminis f. sp. tritici, including two races from the race TTKSK complex. This phenotyping led to the identification of accessions with either adult-plant or all-stage resistance to race TTKSK, and often North American races of P. graminis f. sp. tritici as well. These Ug99 resistant accessions can be obtained by breeders and introgressed into current breeding germplasm.

scholarly journals Resistance to Stripe Rust in Five Durum Wheat Cultivars

Plant Disease ◽  
1997 ◽  
Vol 81 (1) ◽  
pp. 27-30 ◽  
Author(s):  
Hong Ma ◽  
Ravi P. Singh ◽  
Osman Abdalla
Keyword(s):  
Durum Wheat ◽  
Stripe Rust ◽  
Puccinia Striiformis ◽  
Infection Type ◽  
Field Resistance ◽  
Adult Plant ◽  
Growth Stages ◽  
Resistant Cultivars ◽  
Gene Segregation ◽  
Additive Action

Durum wheat (Triticum turgidum) cultivars developed by the International Maize and Wheat Improvement Center (CIMMYT) are currently grown on more than 8 million hectares worldwide. Because of the lack of information on the genetic basis of resistance to stripe rust (caused by Puccinia striiformis), crosses in a diallel arrangement (without reciprocals) were made among five worldwide resistant cultivars and the susceptible cultivar Local Red. Inheritance of resistance was investigated in seedling and adult plant growth stages of F2 populations, and F3lines. The low seedling infection type of each resistant cultivar, namely Kroub 76, Chonta Inia, Sna 3, Syros, and Arena, was based on the additive action of the same two genes. Each of these genes conferred intermediate infection types when present alone. The field resistance of the cultivars was based on the additive action of the two genes identified in the seedlings and one additional, partially effective adult resistance gene. Segregation for plants with stripe rust severities higher than that of the parents in intercrosses of resistant cultivars indicated that some genetic diversity exists for adult genes. The resistance of these cultivars may prove to be long-lasting, since it results from the combined action of at least three genes.

scholarly journals Emergence of Virulence to Sr25 of Puccinia graminis f. sp. tritici on Wheat in India

Plant Disease ◽  
2009 ◽  
Vol 93 (8) ◽  
pp. 840-840 ◽  
Author(s):  
S. K. Jain ◽  
M. Prashar ◽  
S. C. Bhardwaj ◽  
S. B. Singh ◽  
Y. P. Sharma
Keyword(s):  
Resistance Genes ◽  
Stem Rust ◽  
Infection Type ◽  
Adult Plant ◽  
Puccinia Graminis ◽  
Wheat Cultivars ◽  
Sources Of Resistance ◽  
Seedling Resistance ◽  
Additional Gene ◽  
Adult Plants

Stem (black) rust, caused by Puccinia graminis Pers. f. sp. tritici Eriks. & Henn., is one of the most destructive diseases of wheat. It could be controlled through introgression of race-specific resistance genes. However, such kind of resistance is mostly short lived due to emergence of new virulences. For example, resistance genes Sr11, Sr24, Sr30, and Sr31 are no longer effective (2,4). Detection of new virulences has remained vital in the evaluation and identification of new sources of resistance. We report here the detection of virulence to Sr25, a gene from Thinopyrum elongatum (4), which had been effective or partially effective against stem rust worldwide, including race Ug99 (TTKSK) (4). A stem rust isolate collected in 2006 from Karnataka (southern India) produced susceptible reactions (infection type [IT] 3+ to 4) on the primary leaves of differential genotype ‘Agatha’ carrying Sr25 and susceptible check ‘Agra Local’ at 22 ± 2°C. To verify virulence to Sr25, single-pustule isolates from this sample were inoculated onto seedlings of ‘Agrus’, ‘Agatha’, ‘RL6040’ (‘Thatcher’ + Sr25), ‘Superseri#1’, ‘Wheatear’, and ‘Morocco’ + Sr25 (obtained from CIMMYT), which all carry Sr25. All these accessions were found susceptible (IT 3+ to 4) to this isolate, except Wheatear which expressed resistance (IT ;1), indicating the presence of additional gene(s). These genotypes are resistant (ITs ;1 to 2+) to Sr25-avirulent pathotypes. The new pathotype is avirulent to Sr11, 13, 14, 21, 22, 23, 24, 26, 27, 29, 31, 32, 33, 35, 37, 38, 39, 40, 43, and Tmp and virulent to Sr5, 6, 7a, 7b, 8a, 9a, 9b, 9d, 9e, 9f, 9g, 10, 12, 15, 16, 17, 18, 19, 20, 25, 28, 30, 34, 36, 42, Wld-1, and Gt at 22 ± 2°C. This pathotype has been designated as 58G13-3 and PKTSC according to the Indian nomenclature (1) and the North American system (3), respectively. It represents race 40 based on Stakman's differentials. It may have arisen from race 40 through mutation. The type culture of the pathotype has been added to the culture collection at Flowerdale, Shimla. Interestingly, ‘Festiguay’ (Sr30) was found resistant to this pathotype, indicating the presence of additional gene(s), whereas ‘Webster’ (Sr30) was susceptible. Adult plants of Agrus, Agatha, RL6040, Superseri#1, and Morocco+Sr25 also were susceptible, producing 20S to 60S responses. Sr25-avirulent pathotype 62G29 produced a TR (flecking in traces) response on these lines except Morocco + Sr25 that showed 20 to 40MR (moderately resistant) responses. In the same study however, adult plants of Thatcher showed a resistant reaction (10R to MR) at low (16 ± 2°C) and susceptible (20S) at high (22 ± 2°C) temperatures. Agatha and RL6040, having Thatcher as one of the parents, had similar responses. The detection of Sr25 virulence is significant since Sr25 is an important gene to be targeted for breeding wheat cultivars resistant to Ug99. We should use either adult plant resistance and/or pyramiding two or more genes for seedling resistance to enhance the field life of wheat cultivars. References: (1) P. Bahadur et al. Proc. Indian Acad. Sci. 95:29, 1985. (2) S. C. Bhardwaj et al. J. Wheat Res. 1:51, 2007. (3) Y. Jin et al. Plant Dis. 92:923, 2008. (4) R. P. Singh et al. CAB Rev. No. 054:1, 2006.

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