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Rust Resistance Genes (rust + resistance_gene)

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Life Sciences100%

Selected Abstracts

Wheat leaf rust resistance gene Lr59 derived from Aegilops peregrina

PLANT BREEDING, Issue 4 2008
G. F. Marais
Abstract An Aegilops peregrina (Hackel in J. Fraser) Maire & Weiller accession that showed resistance to mixed leaf rust (Puccinia triticina Eriks.) inoculum was crossed with, and backcrossed to, hexaploid wheat (Triticum aestivum L.). During backcrossing a chromosome segment containing a leaf rust resistance gene (here designated Lr59) was spontaneously translocated to wheat chromosome 1A. Meiotic, monosomic and microsatellite analyses suggested that the translocated segment replaced most of, or the complete, 1AL arm, and probably resulted from centromeric breaks and fusion. The translocation, of which hexaploid wheat line 0306 is the appropriate source material, provided seedling leaf rust resistance against a wide range of South African and Canadian pathotypes. [source]

Microsatellite marker for yellow rust resistance gene Yr5 in wheat introgressed from spelt wheat

PLANT BREEDING, Issue 6 2002
Q. Sun
Abstract Yellow rust of wheat caused by Puccinia striiformis f sp. tritici has been periodically epidemic and severely damaged wheat production in China and throughout the world. Breeding for resistant cultivars has been proved to be an effective way to resolve the problem. A yellow rust resistance gene, Yr5, derived from Triticum spelta shows immunity or high resistance to the most popular isolates Tiaozhong 30 and 31 in China. Establishment of DNA markers for the Yr5 gene will facilitate marker-assisted selection and gene pyramiding in the breeding programme. Since the Yr5 gene was cytologically located on the long arm of chromosome 2B, By33, the donor of Yr5, was crossed and backcrossed with the susceptible line 441, and BC3F2 and BC3F3 segregating populations were screened for polymorphism by using 11 microsatellite primers mapped on chromosome 2B. A marker, Xgwm501-195 bp/160 bp, was found to be linked to Yr5, with a genetic distance of 10.5-13.3 cM. [source]

A microsatellite marker linked to leaf rust resistance transferred from Aegilops triuncialis into hexaploid wheat

PLANT BREEDING, Issue 3 2001
M. Aghaee-Sarbarzeh
Abstract Aegilops triuncialis (UUCC) is an excellent source of resistance to various wheat diseases, including leaf rust. Leaf rust-resistant derivatives from a cross of a highly susceptible Triticum aestivum cv.,WL711' as the recurrent parent and Ae. triuncialis Ace.3549 as the donor and with and without a pair of acrocentric chromosomes were used for molecular tagging. The use of a set of sequence tagged microsatellite (STMS) markers already mapped to different wheat chromosomes unequivocally indicated that STMS marker gwm368 of chromosome 4BS was tightly linked to the Ae. triuncialis leaf rust resistance gene transferred to wheat. The presence of the Ae. Triuncialis -specific STMS gwm368 homoeoallele along with the non-polymorphic 4BS allele in the rust-resistant derivatives with and without the acrocentric chromosome indicates that the resistance has been transferred from the acrocentric chromosome to either the A or the D genome of wheat. This alien leaf rust resistance gene has been temporarily named as LrTr. [source]

Two different CC-NBS-LRR genes are required for Lr10 -mediated leaf rust resistance in tetraploid and hexaploid wheat

THE PLANT JOURNAL, Issue 6 2009
Caroline Loutre
Summary Comparative study of disease resistance genes in crop plants and their relatives provides insight on resistance gene function, evolution and diversity. Here, we studied the allelic diversity of the Lr10 leaf rust resistance gene, a CC-NBS-LRR coding gene originally isolated from hexaploid wheat, in 20 diploid and tetraploid wheat lines. Besides a gene in the tetraploid wheat variety ,Altar' that is identical to the hexaploid wheat Lr10, two additional, functional resistance alleles showing sequence diversity were identified by virus-induced gene silencing in tetraploid wheat lines. In contrast to most described NBS-LRR proteins, the N-terminal CC domain of LR10 was found to be under strong diversifying selection. A second NBS-LRR gene at the Lr10 locus, RGA2, was shown through silencing to be essential for Lr10 function. Interestingly, RGA2 showed much less sequence diversity than Lr10. These data demonstrate allelic diversity of functional genes at the Lr10 locus in tetraploid wheat, and these new genes can now be analyzed for agronomic relevance. Lr10 -based resistance is highly unusual both in its dependence on two, only distantly, related CC-NBS-LRR proteins, as well as in the pattern of diversifying selection in the N-terminal domain. This indicates a new and complex molecular mechanism of pathogen detection and signal transduction. [source]

Allosyndetic recombinants of the Aegilops peregrina- derived Lr59 translocation in common wheat

PLANT BREEDING, Issue 4 2010
G. F. Marais
With 2 figures and 2 tables Abstract The wild relatives constitute a valuable source of rust resistance genes that can be utilized in wheat breeding. However, translocation of desirable genes through chromosome engineering inevitably results in co-transfer of deleterious wild species chromatin. An attempt was made to replace such redundant alien chromatin on the Lr59 translocation through homoeologous chromosome pairing and crossing over in the absence of Ph1. Strong segregation distortion resulted in the recovery of an unexpectedly high frequency of resistant recombinants. Eight of these retained comparatively short, distal segments of foreign chromatin, including Lr59. The foreign chromatin that remained in the latter plants was characterized with the use of twelve anonymous AFLP loci, the data of which suggested reduced homoeology with 1AL that could have been the result of a sub-terminal, paracentric inversion. Crossing over within an inversion loop may have resulted in a low frequency of genetically unbalanced gametes. It will therefore be necessary to develop near-isogenic lines of the eight recombinants and to do field evaluations in order to identify those that retained the shortest, balanced translocations. [source]

Development of SCAR markers for identification of stem rust resistance gene Sr31 in the homozygous or heterozygous condition in bread wheat

PLANT BREEDING, Issue 6 2006
B. K. Das
Abstract The stem rust resistance gene Sr31, transferred from rye (Secale cereale) into wheat (Triticum aestivum L.) imparts resistance to all the virulent pathotypes of stem rust (Puccinia graminis f. sp. tritici) found in India. Wheat genotypes including carriers and non-carriers of the Sr31 gene were analysed using arbitrary primed polymerase chain reaction (AP-PCR). AP-PCR markers viz. SS30.2580(H) associated with the Sr31 gene and SS26.11100 associated with the allele for susceptibility were identified. Linkage between the markers and phenotypes was confirmed by analysing an F2 population obtained from a cross between a resistant and a susceptible genotype. The markers were tightly linked to the respective alleles. Both the AP-PCR markers were converted into sequence characterized amplified region (SCAR) markers, viz. SCSS30.2576 and SCSS26.11100 respectively. The markers were validated in two more segregating populations and 49 wheat genotypes. Using both markers it was possible to distinguish the homozygous from the heterozygous carriers of the Sr31 gene in the F2 generation. The markers developed in this study can be used for pyramiding of the Sr31 gene with other rust resistance genes and in marker-assisted selection. [source]

Leaf rust and stripe rust resistance genes Lr54 and Yr37 transferred to wheat from Aegilops kotschyi

PLANT BREEDING, Issue 6 2005
G. F. Marais
Abstract The tendency of unpaired meiotic chromosomes to undergo centric misdivision was exploited to translocate leaf rust and stripe rust resistance genes from an Aegilops kotschyi addition chromosome to a group 2 chromosome of wheat. Monosomic and telosomic analyses showed that the translocation occurred to wheat chromosome arm 2DL. The introgressed region did not pair with the corresponding wheat 2DL telosome during meiosis suggesting that a whole arm may have been transferred. Female transmission of the resistance was about 55% whereas male transmission was strongly preferential (96%). The symbols Lr54 and Yr37 are proposed to designate the new resistance genes. [source]

Inheritance of rust resistance genes and molecular markers in microspore-derived populations of flax

PLANT BREEDING, Issue 1 2001
Y. Chen
Abstract The inheritance patterns of rust resistance genes and molecular markers in microspore-derived populations of flax were investigated. Plants were produced from anther culture of F1 plants from two crosses. Microspore-derived plants in anther culture of flax were identified using molecular markers. Two rust resistance genes and three out of six molecular markers were inherited in expected Mendelian ratios in microspore-derived populations. Distorted segregation for the other three molecular markers was shown to be the result of over-representation of genomic fragments from the more responsive parent in the F1 donor plant. The implication of this study in relation to androgenesis and flax breeding using anther culture is discussed. [source]