scholarly journals Identifying New Sources of Resistance to Eyespot of Wheat in Aegilops longissima

Plant Disease ◽  
2013 ◽  
Vol 97 (3) ◽  
pp. 346-353 ◽  
Author(s):  
H. Sheng ◽  
T. D. Murray
Keyword(s):  
Resistance Genes ◽  
Wheat Breeding ◽  
Sources Of Resistance ◽  
Substitution Lines ◽  
Complete Control ◽  
Chromosome Addition ◽  
Eyespot Resistance ◽  
Aegilops Longissima ◽  
Wheat Improvement ◽  
Oculimacula Yallundae

Eyespot, caused by Oculimacula yallundae and O. acuformis, is an economically important disease of wheat. Currently, two eyespot resistance genes, Pch1 and Pch2, are used in wheat breeding programs but neither provides complete control or prevents yield loss. Aegilops longissima is a distant relative of wheat and proven donor of genes useful for wheat improvement, including disease resistance. Forty A. longissima accessions and 83 A. longissima chromosome addition or substitution lines were evaluated for resistance to eyespot. Among the 40 accessions tested, 43% were resistant to O. yallundae, 48% were resistant to O. acuformis, and 33% were resistant to both. Addition or substitution lines containing chromosomes 1S1, 2S1, 5S1, and 7S1, and a 4S17S1 translocation were resistant to O. yallundae. Chromosomes 1S1, 2S1, 4S1, and 5S1 contributed to resistance to O. acuformis more than others. Chromosomes 1S1, 2S1, 5S1, and 7S1 provided resistance to both pathogens. This is the first report of eyespot resistance in A. longissima. These results provide evidence that genetic control of eyespot resistance is present on multiple chromosomes of the S1 genome. This research demonstrates that A. longissima is a potential new source of eyespot resistance genes that could broaden the genetic diversity for wheat improvement.

Resistance to soil-borne diseases of wheat: Contributions from the wheatgrasses Thinopyrum intermedium and Th. ponticum

2008 ◽  
Vol 88 (1) ◽  
pp. 195-205 ◽  
Author(s):  
Hongjie Li ◽  
R. L. Conner ◽  
T. D. Murray
Keyword(s):  
Resistance Genes ◽  
Root Rot ◽  
Vascular System ◽  
Bipolaris Sorokiniana ◽  
Wheat Breeding ◽  
Thinopyrum Intermedium ◽  
Common Root ◽  
Chromosome Addition ◽  
Common Root Rot ◽  
Oculimacula Yallundae

Eyespot, Cephalosporium stripe, and common root rot are soil-borne diseases that damage the stem bases, vascular system, subcrown internodes,and roots of wheat. Resistance in wheat to these diseases is insufficient to prevent significant yield loss when disease is severe. The wheatgrasses Thinopyrum intermedium and Th. ponticum are highly resistant to these diseases. Identification of disease-resistant wheat-Thinopyrum partial amphiploids, chromosome addition, substitution, and translocation lines makes them a valuable source of resistance genes for wheat breeding programs. Single chromosomes or chromosome segments containing resistance genes can be transferred into wheat to produce genetic stocks that afford a better understanding of the genetic control of resistance in wheatgrasses and new genetic resources for wheat improvement. Resistance to eyespot in Th. intermedium and Th. ponticum was associated with the homoeologous group 4 chromosomes, whereas resistance to Cephalosporium stripe was controlled by genes located on chromosomes 3 and 6 of Th. ponticum. Despite the fact that some eyespot- and common root rot-resistant wheat-Thinopyrum lines have blue kernels, resistance is not tightly linked to the blue aleurone trait. Key words: Thinopyrum intermedium, Th. ponticum, eyespot, Cephalosporium stripe, common root rot, Oculimacula yallundae, O. acuformis, Cephalosporium gramineum, Bipolaris sorokiniana

scholarly journals Resistance of Wheat Line Kavkaz-K4500 L.6.A.4 to Septoria Tritici Blotch Controlled by Isolate-Specific Resistance Genes

2005 ◽  
Vol 95 (6) ◽  
pp. 664-671 ◽  
Author(s):  
L. Chartrain ◽  
S. T. Berry ◽  
J. K. M. Brown
Keyword(s):  
Resistance Genes ◽  
Specific Resistance ◽  
Field Resistance ◽  
Field Conditions ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
High Susceptibility ◽  
Sources Of Resistance ◽  
Wheat Improvement ◽  
The Uk

The International Maize and Wheat Improvement Center (CIMMYT), Mexico, germplasm-derived wheat (Triticum aestivum) Kavkaz-K4500 L.6.A.4 (KK) is one of the major sources of resistance to Septoria tritici blotch (STB). KK is resistant to STB in field conditions in the UK even though a large majority of Mycosphaerella graminicola isolates are virulent to it. The genetics of the resistance of KK to four isolates of M. graminicola were investigated. KK has at least five isolate-specific resistance genes including Stb6 on chromosome 3A plus a second gene for resistance to isolate IPO323, two genes on chromosome 4A, both in the region where Stb7 is located with one designated as Stb12, and a gene designated Stb10 on chromosome 1D. Taken together, the widespread use of KK as a source of resistance to STB, its high resistance in field conditions, and its high susceptibility to M. graminicola isolates, which are virulent to all its resistance genes, suggest that high levels of field resistance to STB might be achieved by pyramiding several isolate-specific resistance genes.

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 How do eyespot resistance genes transferred into winter wheat breeding lines affect their yield?

2016 ◽  
Vol 56 (4) ◽  
pp. 319-322 ◽  
Author(s):  
Michał Kwiatek ◽  
Halina Wiśniewska ◽  
Marek Korbas ◽  
Magdalena Gawłowska ◽  
Jolanta Belter ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Wheat Variety ◽  
Wheat Breeding ◽  
Aegilops Ventricosa ◽  
Wheat Varieties ◽  
Breeding Lines ◽  
Eyespot Resistance ◽  
Limited Effectiveness ◽  
Wheat Lines ◽  
Resistance Expression

Abstract Eyespot can reduce yields, even up to 50%. There are four genetically characterized resistances in wheat varieties, controlled by: (1) the Pch1 gene, transferred from Aegilops ventricosa; (2) the Pch2 gene, originating from wheat variety Capelle Desprez; (3) the Pch3 gene, originating from Dasypyrum villosum; and (4) the Q.Pch.jic-5A gene, a quantitative trait locus (QTL) located on chromosome 5A of Capelle Desprez. However, those loci have drawbacks, such as linkage of Pch1 with deleterious traits and limited effectiveness of Pch2 against the disease. Here we present an initial study which aims to characterize wheat pre-registration breeding lines carrying 12 eyespot resistance genes, consider their resistance expression in inoculation tests and the influence of resistance genotypes on the yield. We selected four groups of breeding lines, carrying: (1) the Pch1 gene alone: one line; (2) the Pch2 gene alone: four lines; (3) the Q.Pch.jic-5A gene alone: one line; and (4) Pch1 + Q.Pch.jic-5A: three lines. For the first time, the effect of the combination of Pch1 and Q.Pch.jic-5A genes was compared with resistance conferred by Pch1 or Q.Pch.jic-5A alone. We found significant differences between infection scores evaluated in resistant lines carrying Pch1 and Q.Pch.jic-5A alone, while no differences in terms of the level of resistance expression were detected between Pch1 alone and Pch1 + Q.Pch.jic-5A, and between wheat lines carrying Pch1 and Pch2 alone. Moreover, we demonstrated that the Pch1 gene, together with an Ae. ventricosa segment, caused statistically significant yield losses, both as a single eyespot resistance source or in a combination with Q.Pch.jic-5A. Yield scores showed that wheat lines with Q.Pch.jic-5A had the highest yields, similar to the yielding potential of Pch2-bearing lines and control varieties.

scholarly journals Evolution of Physiologic Races and Virulence of Puccinia striiformis on Wheat in Syria and Lebanon

Plant Disease ◽  
2002 ◽  
Vol 86 (5) ◽  
pp. 499-504 ◽  
Author(s):  
A. H. Yahyaoui ◽  
M. S. Hakim ◽  
M. El Naimi ◽  
N. Rbeiz
Keyword(s):  
Resistance Genes ◽  
Puccinia Striiformis ◽  
Yellow Rust ◽  
Wheat Breeding ◽  
Natural Conditions ◽  
Breeding Programs ◽  
Land Race ◽  
Physiologic Races ◽  
Resistant Genotypes

Virulence-avirulence phenotypes of Puccinia striiformis isolates collected in Lebanon and Syria were determined on seedlings of the wheat-yellow rust differential genotypes. We found 25 and 11 physiologic races over 6 years (1994 to 1999) in Syria and Lebanon, respectively. The composition of physiologic races found in Syria and Lebanon differed greatly between 1994 and 1999. Races identified in 1999, such as 230E150 and 230E134, have wider spectra of virulence on resistant genotypes than races collected in 1994. In Lebanon, three races were found in 1994 compared with six races in 1999. Yellow rust differential genotypes were used in a trap nursery to monitor yellow rust populations under natural conditions. Races identified from cultivars in the trap nursery in Syria and Lebanon, and from land race cultivars in Iraq, were recovered among the races identified from farm fields. Yellow rust samples were collected from Yemen, and none of the races identified from Yemen samples were identical to those in Syria and Lebanon. Virulence frequencies in the yellow rust population on the differential genotypes tested in the trap nurseries were above 70% for some resistance genes. Yellow rust populations in Syria and Lebanon have diverse virulence phenotypes. P. striiformis populations appear to be changing over, and this would be an important consideration for wheat breeding programs in the region.

scholarly journals Stem Rust Resistance in A-Genome Diploid Relatives of Wheat

Plant Disease ◽  
2011 ◽  
Vol 95 (8) ◽  
pp. 941-944 ◽  
Author(s):  
M. N. Rouse ◽  
Y. Jin
Keyword(s):  
Resistance Genes ◽  
Stem Rust ◽  
Rust Resistance ◽  
Infection Type ◽  
Genetic Resistance ◽  
Wheat Breeding ◽  
Stem Rust Resistance ◽  
Wheat Stem Rust ◽  
A Genome ◽  
Stem Rust Resistance Genes

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, has been effectively controlled through the use of genetic resistance. P. graminis f. sp. tritici race TTKSK (Ug99) possesses virulence to many resistance genes that have been used in wheat breeding worldwide. One strategy to aid breeders in developing resistant cultivars is to utilize resistance genes transferred from wild relatives to wheat. Stem rust resistance genes have previously been introgressed from Triticum monococcum to wheat. In order to identify additional resistance genes, we screened 1,061 accessions of T. monococcum and 205 accessions of T. urartu against race TTKSK and four additional P. graminis f. sp. tritici races: TTTTF, TRTTF, QFCSC, and MCCFC. A high frequency of the accessions (78.7% of T. monococcum and 93.0% of T. urartu) were resistant to P. graminis f. sp. tritici race TTKSK, with infection types ranging from 0 to 2+. Among these resistant accessions, 55 T. monococcum accessions (6.4% of the total) were also resistant to the other four races. Associations of resistance in T. monococcum germplasm to different races indicated the presence of genes conferring resistance to multiple races. Comparing the observed infection type patterns to the expected patterns of known genes indicated that previously uncharacterized genes for resistance to race TTKSK exist in both T. monococcum and T. urartu.

scholarly journals Identification and Molecular Mapping of a Gene Conferring Resistance to Pyrenophora tritici-repentis Race 3 in Tetraploid Wheat

2006 ◽  
Vol 96 (8) ◽  
pp. 885-889 ◽  
Author(s):  
P. K. Singh ◽  
J. L. Gonzalez-Hernandez ◽  
M. Mergoum ◽  
S. Ali ◽  
T. B. Adhikari ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Molecular Mapping ◽  
Recombinant Inbred Lines ◽  
Tetraploid Wheat ◽  
Recessive Gene ◽  
Tan Spot ◽  
Substitution Lines ◽  
Disease Reaction ◽  
Pyrenophora Tritici Repentis ◽  
The Cross

Race 3 of the fungus Pyrenophora tritici-repentis, causal agent of tan spot, induces differential symptoms in tetraploid and hexaploid wheat, causing necrosis and chlorosis, respectively. This study was conducted to examine the genetic control of resistance to necrosis induced by P. tritici-repentis race 3 and to map resistance genes identified in tetraploid wheat (Triticum turgidum). A mapping population of recombinant inbred lines (RILs) was developed from a cross between the resistant genotype T. tur-gidum no. 283 (PI 352519) and the susceptible durum cv. Coulter. Based on the reactions of the Langdon-T. dicoccoides (LDN[DIC]) disomic substitution lines, chromosomal location of the resistance genes was determined and further molecular mapping of the resistance genes for race 3 was conducted in 80 RILs of the cross T. turgidum no. 283/Coulter. Plants were inoculated at the two-leaf stage and disease reaction was assessed 8 days after inoculation based on lesion type. Disease reaction of the LDN(DIC) lines and molecular mapping on the T. turgidum no. 283/Coulter population indicated that the gene, designated tsn2, conditioning resistance to race 3 is located on the long arm of chromosome 3B. Genetic analysis of the F2 generation and of the F4:5 and F6:7 families indicated that a single recessive gene controlled resistance to necrosis induced by race 3 in the cross studied.

scholarly journals Using markers and field evaluation to identify the source of eyespot resistance genePch1in the collection of wheat breeding lines

2015 ◽  
Vol 43 (4) ◽  
pp. 638-648 ◽  
Author(s):  
M. Kwiatek ◽  
H. Wiśniewska ◽  
Z. Kaczmarek ◽  
M. Korbas ◽  
M. Gawłowska ◽  
...  
Keyword(s):  
Field Evaluation ◽  
Wheat Breeding ◽  
Breeding Lines ◽  
Eyespot Resistance

scholarly journals Sources of resistance to Crinipellis perniciosa in progenies of cacao accessions collected in the Brazilian Amazon

2006 ◽  
Vol 63 (6) ◽  
pp. 572-578 ◽  
Author(s):  
Valéria Rodrigues Lavigne de Mello Paim ◽  
Edna Dora Martins Newman Luz ◽  
José Luís Pires ◽  
Stela Dalva Vieira Midlej Silva ◽  
Jorge Teodoro de Souza ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Integrated Management ◽  
Durable Resistance ◽  
Brazilian Amazon ◽  
Sources Of Resistance ◽  
Crinipellis Perniciosa ◽  
Broom Disease ◽  
The Mean ◽  
The Stability ◽  
Different Sources

The witches' broom disease caused by the fungus Crinipellis perniciosa is the main phytossanitary constraint for cacao production in Brazil. The integrated management of the disease involves resistance as one of the components. The breeding program conducted by the Brazilian Institution, CEPLAC is directed toward the pyramidation of resistance genes from different sources to achieve a more durable resistance. This study aimed to identify sources of resistance in progenies of cacao accessions collected in the basins of ten Amazonian rivers and compared to progenies from the Peruvian clones 'Scavina 6' and 'Sacavina 12'. Progenies from 40 Amazonian accessions and 'Scavina' were evaluated in the field for six years for witches' broom resistance through multivariate and repeated measurement analyses evaluating the effect of progeny, area, block, year, and their interactions. There were differences in the mean number of vegetative brooms on some Amazonian progenies and 'Scavina' descendants. There was an increase in the number of vegetative brooms in the last year for 'Scavina' progenies, but that was not observed for the Amazonian progenies 64, 66, 156, 194, 195, 269 and 274. There were different gene/alleles for resistance in the Amazonian progenies in comparison to the traditional 'Scavina' accessions. These new sources of resistance will be important for pyramiding resistance genes and consequently increasing the stability and durability of the resistance to witches' broom.

scholarly journals Race structure of cowpea witchweed (Striga gesnerioides) in West Africa and its implications for Striga resistance breeding of cowpea

Weed Science ◽  
2020 ◽  
Vol 68 (2) ◽  
pp. 125-133 ◽  
Author(s):  
Erik W. Ohlson ◽  
Michael P. Timko
Keyword(s):  
West Africa ◽  
Resistance Genes ◽  
Broad Spectrum ◽  
Genetic Relatedness ◽  
Durable Resistance ◽  
Resistance Breeding ◽  
Differential Resistance ◽  
African Countries ◽  
Sources Of Resistance ◽  
Striga Gesnerioides

AbstractCowpea witchweed [Striga gesnerioides (Willd.) Vatke] is a primary constraint of cowpea [Vigna unguiculata (L.) Walp.] production in West Africa. Previously, seven S. gesnerioides races were classified based upon host specificity and genotypic profiling. Because race number and distribution are dynamic systems influenced by gene flow, genetic drift, and natural selection, a thorough investigation of S. gesnerioides diversity and the effectiveness of known sources of resistance in cowpea is needed to develop varieties with durable and broad-spectrum Striga resistance. In this study, we screened seven cowpea lines against 58 unique S. gesnerioides populations collected from across nine West African countries. Individuals from 10 S. gesnerioides populations were genotyped with simple sequence repeat (SSR) markers. We identified six races of S. gesnerioides based on their parasitism of the seven cowpea lines with known differential resistance genotypes. No cowpea line was resistant to all 58 Striga populations and none of the Striga populations were able to overcome the resistance of all seven lines. A novel race, SG6, of the parasite collected from Kudu, Nigeria, was found to overcome more cowpea resistance genes than any previously reported race. SSR analysis indicates that Striga populations are highly differentiated and genetic relatedness generally corresponds with geographic proximity rather than their host compatibility. Due to the dearth of broad-spectrum resistance found among Striga-resistant cowpea lines, there exists a need to stack multiple Striga resistance genes in order to confer broad-spectrum and durable resistance.

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