Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 34
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Theor Appl Genet ; 132(11): 3169-3176, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31463519

RESUMO

KEY MESSAGE: Stripe rust resistance gene, Yr82, was mapped in chromosome 3BL using SNP markers. Yr82 interacted with Yr29 to produce lower stripe rust responses at the adult plant stage. Landrace Aus27969 produced low infection types against Australian Puccinia striiformis f. sp. tritici (Pst) pathotypes. A recombinant inbred line (RIL) F7 population from the Aus27969/Avocet S cross was developed. Monogenic segregation for seedling stripe rust response was observed among the RIL population, and the resistance locus was named Yr82. Bulk segregant analysis performed using the iSelect wheat 90 K Infinium SNP array located Yr82 in the long arm of chromosome 3B. The RIL population was screened against stripe rust under field conditions and was genotyped with targeted genotyping-by-sequencing assay. QTL analysis detected the involvement of chromosomes 1B and 3B in controlling stripe rust resistance carried by Aus27969. Incorporation of Yr82 and marker SNPLr46G22 into the linkage map showed that the QTL in 1B and 3B represented Yr29 and Yr82, respectively. Kompetitive allele-specific PCR (KASP) markers sun KASP_300 and KASP_8775 flanked Yr82 distally and proximally, respectively, each at 2 cM distance. These Yr82-linked markers were polymorphic among 84% of Australian cultivars and can be used for marker-assisted selection of Yr82.

2.
Plant Dis ; 103(6): 1166-1171, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30998448

RESUMO

The deployment of diverse sources of resistance in new cultivars underpins durable control of rust diseases. Aus27430 exhibited a moderate level of stripe rust resistance against Puccinia striiformis f. sp. tritici (Pst) pathotypes currently prevalent in Australia. Aus27430 was crossed with the susceptible parent Avocet S (AvS) and subsequent filial generations were raised. Monogenic segregation observed among Aus27430/AvS F3 families was confirmed through stripe rust screening of an F6 recombinant inbred line (RIL) population, and the resistance locus was temporarily named YrAW5. Selective genotyping using an Illumina iSelect 90K wheat SNP bead chip array located YrAW5 in chromosome 6A. Genetic mapping of the RIL population with linked 90K SNPs that were converted into PCR-based marker assays, as well as SSR markers previously mapped to chromosome 6A, confirmed the chromosomal assignment for YrAW5. Comparative analysis of other stripe rust resistance genes located in chromosome 6A led to the formal designation of YrAW5 as Yr81. Tests with a marker linked with Yr18 also demonstrated the presence of this gene in Aus27430. Yr18 interacted with Yr81 to produce stripe rust responses lower than those produced by RILs carrying these genes individually. Although gwm459 showed higher recombination with Yr81 compared with the other flanking marker KASP_3077, it amplified the AvS allele in 80 cultivars, whereas KASP_3077 amplified AvS allele in 67 cultivars. Both markers can be used in marker-assisted selection after confirming parental polymorphism.


Assuntos
Cromossomos de Plantas , Resistência à Doença , Triticum , Austrália , Basidiomycota/fisiologia , Mapeamento Cromossômico , Cromossomos de Plantas/genética , Resistência à Doença/genética , Marcadores Genéticos/genética , Triticum/genética , Triticum/microbiologia
3.
Nat Biotechnol ; 37(2): 139-143, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30718880

RESUMO

Disease resistance (R) genes from wild relatives could be used to engineer broad-spectrum resistance in domesticated crops. We combined association genetics with R gene enrichment sequencing (AgRenSeq) to exploit pan-genome variation in wild diploid wheat and rapidly clone four stem rust resistance genes. AgRenSeq enables R gene cloning in any crop that has a diverse germplasm panel.


Assuntos
Clonagem Molecular , Produtos Agrícolas/genética , Resistência à Doença/genética , Genes de Plantas , Doenças das Plantas/genética , Mapeamento Cromossômico , Estudos de Associação Genética , Variação Genética , Genômica , Genótipo , Modelos Genéticos , Fenótipo , Filogenia , Polimorfismo de Nucleotídeo Único , Plântula , Triticum/genética
4.
Nat Commun ; 9(1): 3735, 2018 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-30282993

RESUMO

Yellow rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a devastating fungal disease threatening much of global wheat production. Race-specific resistance (R)-genes are used to control rust diseases, but the rapid emergence of virulent Pst races has prompted the search for a more durable resistance. Here, we report the cloning of Yr15, a broad-spectrum R-gene derived from wild emmer wheat, which encodes a putative kinase-pseudokinase protein, designated as wheat tandem kinase 1, comprising a unique R-gene structure in wheat. The existence of a similar gene architecture in 92 putative proteins across the plant kingdom, including the barley RPG1 and a candidate for Ug8, suggests that they are members of a distinct family of plant proteins, termed here tandem kinase-pseudokinases (TKPs). The presence of kinase-pseudokinase structure in both plant TKPs and the animal Janus kinases sheds light on the molecular evolution of immune responses across these two kingdoms.

5.
Theor Appl Genet ; 131(7): 1459-1467, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29560515

RESUMO

KEY MESSAGE: A new adult plant stripe rust resistance gene, Yr80, was identified in a common wheat landrace Aus27284. Linked markers were developed and validated for their utility in marker-assisted selection. Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is among the most important constraints to global wheat production. The identification and characterisation of new sources of host plant resistance enrich the gene pool and underpin deployment of resistance gene pyramids in new cultivars. Aus27284 exhibited resistance at the adult plant stage against predominant Pst pathotypes and was crossed with a susceptible genotype Avocet S. A recombinant inbred line (RIL) population comprising 121 lines was developed and tested in the field at three locations in 2016 and two in 2017 crop seasons. Monogenic segregation for adult plant stripe rust response was observed among the Aus27284/Avocet S RIL population and the underlying locus was temporarily designated YrAW11. Bulked-segregant analysis using the Infinium iSelect 90K SNP wheat array placed YrAW11 in chromosome 3B. Kompetitive allele specific PCR (KASP) primers were designed for the linked SNPs and YrAW11 was flanked by KASP_65624 and KASP_53292 (3 cM) proximally and KASP_53113 (4.9 cM) distally. A partial linkage map of the genomic region carrying YrAW11 comprised nine KASP and two SSR markers. The physical position of KASP markers in the pseudomolecule of chromosome 3B placed YrAW11 in the long arm and the location of markers gwm108 and gwm376 in the deletion bin 3BL2-0.22 supported this conclusion. As no other stripe rust resistance locus has been reported in chromosome 3BL, YrAW11 was formally designated Yr80. Marker KASP_ 53113 was polymorphic among 94% of 81 Australian wheat cultivars used for validation.


Assuntos
Resistência à Doença/genética , Genes de Plantas , Doenças das Plantas/genética , Triticum/genética , Alelos , Basidiomycota , Mapeamento Cromossômico , Primers do DNA , Marcadores Genéticos , Genótipo , Repetições de Microssatélites , Doenças das Plantas/microbiologia , Polimorfismo de Nucleotídeo Único , Triticum/metabolismo
6.
Theor Appl Genet ; 131(5): 1091-1098, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29396589

RESUMO

KEY MESSAGE: A new leaf rust resistance gene Lr79 has been mapped in the long arm of chromosome 3B and a linked marker was identified for marker-assisted selection. Aus26582, a durum wheat landrace from the A. E. Watkins Collection, showed seedling resistance against durum-specific and common wheat-specific Puccinia triticina (Pt) pathotypes. Genetic analysis using a recombinant inbred line (RIL) population developed from a cross between Aus26582 and the susceptible parent Bansi with Australian Pt pathotype showed digenic inheritance and the underlying loci were temporarily named LrAW2 and LrAW3. LrAW2 was located in chromosome 6BS and this study focused on characterisation of LrAW3 using RILs lacking LrAW2. LrAW3 was incorporated into the DArTseq map of Aus26582/Bansi and was located in chromosome 3BL. Markers linked with LrAW3 were developed from the chromosome survey sequence contig 3B_10474240 in which closely-linked DArTseq markers 1128708 and 3948563 were located. Although bulk segregant analysis (BSA) with the 90 K Infinium array identified 51 SNPs associated with LrAW3, only one SNP-derived KASP marker mapped close to the locus. Deletion bin mapping of LrAW3-linked markers located LrAW3 between bins 3BL11-0.85-0.90 and 3BL7-0.63. Since no other all stage leaf rust resistance gene is located in chromosome 3BL, LrAW3 represented a new locus and was designated Lr79. Marker sun786 mapped 1.8 cM distal to Lr79 and Aus26582 was null for this locus. However, the marker can be reliably scored as it also amplifies a monomorphic fragment that serves as an internal control to differentiate the null status of Aus26582 from reaction failure. This marker was validated among a set of durum and common wheat cultivars and was shown to be useful for marker-assisted selection of Lr79 at both ploidy levels.


Assuntos
Resistência à Doença/genética , Genes de Plantas , Doenças das Plantas/genética , Triticum/genética , Basidiomycota , Mapeamento Cromossômico , Marcadores Genéticos , Genótipo , Doenças das Plantas/microbiologia , Polimorfismo de Nucleotídeo Único , Triticum/microbiologia
7.
Methods Mol Biol ; 1659: 151-162, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28856648

RESUMO

Genetic characterisation of new rust resistance loci in wheat using cytogenetic/low-throughput genotyping systems required at least 5 years. Development of next-generation sequencing (NGS) based molecular marker genotyping platforms in the last decade has provided scientists with the genomic resources to expedite precise mapping of target loci. Here, we describe methodologies for genetic analysis and application of NGS-based resources to determine the precise genomic locations of rust resistance loci in wheat and development of closely linked markers for marker assisted selection.


Assuntos
Mapeamento Cromossômico/métodos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Doenças das Plantas/genética , Triticum/genética , Sequência de Bases , Basidiomycota/fisiologia , DNA de Plantas/genética , Resistência à Doença , Genes de Plantas , Técnicas de Genotipagem/métodos , Doenças das Plantas/microbiologia , Polimorfismo de Nucleotídeo Único , Triticum/microbiologia
8.
Phytopathology ; 107(11): 1381-1387, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28812937

RESUMO

Leaf rust, caused by Puccinia triticina, is a constraint to durum wheat (Triticum turgidum subsp. durum) production, and landraces are reported to be an important source of resistance. Two Portuguese landraces (Aus26582 and Aus26579) showed resistance against durum-specific P. triticina races and were crossed with a susceptible landrace (Bansi) to develop recombinant inbred line (RIL) populations. Monogenic segregation for leaf rust resistance was observed among both RIL populations. The underlying locus, temporarily named LrAW2, was mapped to the short arm of chromosome 6B in the Aus26582/Bansi population and five DArTseq markers cosegregated with LrAW2. Simple sequence repeat markers sun683 and sun684, developed from the chromosome survey sequence (CSS) contig 6BS_2963854, identified through BlastN search of cosegregating DArTseq markers in the International Wheat Genome Sequencing Consortium database, cosegregated with LrAW2. Comparison of the CSS contig 6BS_2963854-based sequences amplified from parental genotypes led to the development of marker sunKASP_60, which also showed close linkage with LrAW2. Markers sun684 and sunKASP_60 showed close association with LrAW2 in both RIL populations. The amplification of LrAW2-specific products by linked markers in Aus26582, Aus26579, and Guayacan (Lr61) indicated that LrAW2 may be Lr61. The alternate amplicon or haplotype produced with LrAW2-linked markers in Australian durum cultivars demonstrated their effectiveness in marker-assisted selection.


Assuntos
Basidiomycota/fisiologia , Predisposição Genética para Doença , Doenças das Plantas/microbiologia , Triticum/genética , Mapeamento Cromossômico , Cromossomos de Plantas , Ligação Genética , Genoma de Planta , Doenças das Plantas/genética
9.
Theor Appl Genet ; 130(4): 777-793, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28255670

RESUMO

KEY MESSAGE: BayesR and MLM association mapping approaches in common wheat landraces were used to identify genomic regions conferring resistance to Yr, Lr, and Sr diseases. Deployment of rust resistant cultivars is the most economically effective and environmentally friendly strategy to control rust diseases in wheat. However, the highly evolving nature of wheat rust pathogens demands continued identification, characterization, and transfer of new resistance alleles into new varieties to achieve durable rust control. In this study, we undertook genome-wide association studies (GWAS) using a mixed linear model (MLM) and the Bayesian multilocus method (BayesR) to identify QTL contributing to leaf rust (Lr), stem rust (Sr), and stripe rust (Yr) resistance. Our study included 676 pre-Green Revolution common wheat landrace accessions collected in the 1920-1930s by A.E. Watkins. We show that both methods produce similar results, although BayesR had reduced background signals, enabling clearer definition of QTL positions. For the three rust diseases, we found 5 (Lr), 14 (Yr), and 11 (Sr) SNPs significant in both methods above stringent false-discovery rate thresholds. Validation of marker-trait associations with known rust QTL from the literature and additional genotypic and phenotypic characterisation of biparental populations showed that the landraces harbour both previously mapped and potentially new genes for resistance to rust diseases. Our results demonstrate that pre-Green Revolution landraces provide a rich source of genes to increase genetic diversity for rust resistance to facilitate the development of wheat varieties with more durable rust resistance.


Assuntos
Basidiomycota , Resistência à Doença/genética , Doenças das Plantas/genética , Triticum/genética , Teorema de Bayes , Mapeamento Cromossômico , Estudos de Associação Genética , Variação Genética , Genótipo , Modelos Lineares , Fenótipo , Doenças das Plantas/microbiologia , Polimorfismo de Nucleotídeo Único , Poliploidia , Locos de Características Quantitativas , Triticum/microbiologia
10.
Theor Appl Genet ; 130(3): 495-504, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27866228

RESUMO

KEY MESSAGE: Fine mapping of Yr47 and Lr52 in chromosome arm 5BS of wheat identified close linkage of the marker sun180 to both genes and its robustness for marker-assisted selection was demonstrated. The widely effective and genetically linked rust resistance genes Yr47 and Lr52 have previously been mapped in the short arm of chromosome 5B in two F3 populations (Aus28183/Aus27229 and Aus28187/Aus27229). The Aus28183/Aus27229 F3 population was advanced to generate an F6 recombinant inbred line (RIL) population to identify markers closely linked with Yr47 and Lr52. Diverse genomic resources including flow-sorted chromosome survey sequence contigs representing the orthologous region in Brachypodium distachyon, the physical map of chromosome arm 5BS, expressed sequence tags (ESTs) located in the 5BS6-0.81-1.00 deletion bin and resistance gene analog contigs of chromosome arm 5BS were used to develop markers to saturate the target region. Selective genotyping was also performed using the iSelect 90 K Infinium wheat SNP assay. A set of SSR, STS, gene-based and SNP markers were developed and genotyped on the Aus28183/Aus27229 RIL population. Yr47 and Lr52 are genetically distinct genes that mapped 0.4 cM apart in the RIL population. The SSR marker sun180 co-segregated with Lr52 and mapped 0.4 cM distal to Yr47. In a high resolution mapping population of 600 F2 genotypes Yr47 and Lr52 mapped 0.2 cM apart and marker sun180 was placed 0.4 cM distal to Lr52. The amplification of a different sun180 amplicon (195 bp) than that linked with Yr47 and Lr52 (200 bp) in 204 diverse wheat genotypes demonstrated its robustness for marker-assisted selection of these genes.


Assuntos
Resistência à Doença/genética , Genes de Plantas , Doenças das Plantas/genética , Triticum/genética , Basidiomycota , Mapeamento Cromossômico , DNA de Plantas/genética , Etiquetas de Sequências Expressas , Ligação Genética , Marcadores Genéticos , Genótipo , Repetições de Microssatélites , Fenótipo , Melhoramento Vegetal , Doenças das Plantas/microbiologia , Polimorfismo de Nucleotídeo Único , Sitios de Sequências Rotuladas , Triticum/microbiologia
11.
Theor Appl Genet ; 130(3): 587-595, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27913833

RESUMO

KEY MESSAGE: The shortening of Aegilops speltoides segment did not facilitate recombination between stem rust resistance genes Sr36 and Sr39 . Robustness of marker rwgs28 for marker-assisted selection of Sr39 was demonstrated. Stem rust resistance genes Sr39 and Sr36 were transferred from Aegilops speltoides and Triticum timopheevii, respectively, to chromosome 2B of wheat. Genetic stocks RL6082 and RWG1 carrying Sr39 on a large and a shortened Ae. speltoides segments, respectively, and the Sr36-carrying Australian wheat cultivar Cook were used in this study. This investigation was planned to determine the genetic relationship between these genes. Stem rust tests on F3 populations derived from RL6082/Cook and RWG1/Cook crosses showed tight repulsion linkage between Sr39 and Sr36. The genomic in situ hybridization analysis of heterozygous F3 family from the RWG1/Cook population showed that the translocated segments do not overlap. Meiotic analysis on the F1 plant from RWG1/Cook showed two univalents at the metaphase and anaphase stages in a majority of the cells indicating absence of pairing. Since meiotic pairing has been reported to initiate at the telomere, pairing and recombination may be inhibited due to very little wheat chromatin in the distal end of the chromosome arm 2BS in RWG1. The Sr39-carrying large Ae. speltoides segment transmitted preferentially in the RL6082/Cook F3 population, whereas the Sr36-carrying T. timopheevii segment over-transmitted in the RWG1/Cook cross. Genotyping with the co-dominant Sr39- and Sr36-linked markers rwgs28 and stm773-2, respectively, matched the phenotypic classification of F3 families. The RWG1 allele amplified by rwgs28 was diagnostic for the shortened Ae. speltoides segment and alternate alleles were amplified in 29 Australian cultivars. Marker rwgs28 will be useful in marker-assisted pyramiding of Sr39 with other genes.


Assuntos
Resistência à Doença/genética , Ligação Genética , Doenças das Plantas/genética , Triticum/genética , Alelos , Basidiomycota , Cromossomos de Plantas , Cruzamentos Genéticos , Genes de Plantas , Marcadores Genéticos , Genótipo , Fenótipo , Melhoramento Vegetal , Doenças das Plantas/microbiologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/microbiologia , Poaceae/genética , Translocação Genética , Triticum/microbiologia
12.
Phytopathology ; 106(12): 1530-1534, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27673348

RESUMO

The quantitative trait loci QYr.sun-3BS and QYr.sun-4DL were identified in the W195/BTSS recombinant inbred line (RIL) population in a previous study. QYr.sun-3BS explained 34 to 59% phenotypic variation in stripe rust response. We evaluated parental genotypes at different growth stages and temperature regimes to detect the critical stage for expression of QYr.sun-3BS. W195 expressed low infection type (IT) ;1C at the fourth leaf stage, when incubated at 21 ± 2°C and the alternate parent BTSS was susceptible (IT 3+). Monogenic segregation for stripe rust response was observed among the RIL population at the fourth leaf stage and the underlying locus was temporarily named YrW195. YrW195 corresponded to QYr.sun-3BS. Since no previously designated stripe rust resistance genes that expresses at and after the fourth leaf stage was mapped in this region, YrW195 was formally named Yr58. Genotyping with Yr46-linked markers indicated the presence of Yr46 in W195, which corresponded to QYr.sun-4DL. The RILs carrying Yr58 and Yr46 singly produced IT 23C and IT 3+, respectively, and those carrying both genes produced IT ;1C indicating the enhancement of Yr58 expression by Yr46. The absence of Yr58-linked alleles of markers sun533 and sun476 in 74 of the 76 wheat cultivars demonstrated their usefulness for marker-assisted selection.


Assuntos
Basidiomycota/fisiologia , Cromossomos de Plantas/genética , Resistência à Doença/genética , Doenças das Plantas/imunologia , Locos de Características Quantitativas/genética , Triticum/genética , Alelos , Cruzamento , Mapeamento Cromossômico , Loci Gênicos/genética , Marcadores Genéticos/genética , Técnicas de Genotipagem , Doenças das Plantas/microbiologia , Folhas de Planta/genética , Folhas de Planta/imunologia , Folhas de Planta/microbiologia , Triticum/imunologia , Triticum/microbiologia
13.
PLoS One ; 11(6): e0157029, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27309724

RESUMO

Stem rust, caused by Puccinia graminis (Pgt), is a damaging disease of wheat that can be controlled by utilizing effective stem rust resistance genes. 'Thatcher' wheat carries complex resistance to stem rust that is enhanced in the presence of the resistance gene Lr34. The purpose of this study was to examine APR in 'Thatcher' and look for genetic interactions with Lr34. A RIL population was tested for stem rust resistance in field nurseries in Canada, USA, and Kenya. BSA was used to find SNP markers associated with reduced stem rust severity. A major QTL was identified on chromosome 3BL near the centromere in all environments. Seedling testing showed that Sr12 mapped to the same region as the QTL for APR. The SNP markers were physically mapped and the region carrying the resistance was searched for sequences with homology to members of the NB-LRR resistance gene family. SNP marker from one NB-LRR-like sequence, NB-LRR3 co-segregated with Sr12. Two additional populations, including one that lacked Lr34, were tested in field nurseries. NB-LRR3 mapped near the maximum LOD for reduction in stem rust severity in both populations. Lines from a population that segregated for Sr12 and Lr34 were tested for seedling Pgt biomass and infection type, as well as APR to field stem rust which showed an interaction between the genes. We concluded that Sr12, or a gene closely linked to Sr12, was responsible for 'Thatcher'-derived APR in several environments and this resistance was enhanced in the presence of Lr34.


Assuntos
Resistência à Doença/genética , Doenças das Plantas/genética , Locos de Características Quantitativas/genética , Triticum/genética , Basidiomycota/patogenicidade , Mapeamento Cromossômico , Cromossomos de Plantas , Epistasia Genética , Genótipo , Fenótipo , Doenças das Plantas/microbiologia , Caules de Planta/crescimento & desenvolvimento , Caules de Planta/microbiologia , Polimorfismo de Nucleotídeo Único , Plântula/genética , Plântula/crescimento & desenvolvimento , Triticum/crescimento & desenvolvimento , Triticum/microbiologia
14.
Nat Biotechnol ; 34(6): 652-5, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27111722

RESUMO

Wild relatives of domesticated crop species harbor multiple, diverse, disease resistance (R) genes that could be used to engineer sustainable disease control. However, breeding R genes into crop lines often requires long breeding timelines of 5-15 years to break linkage between R genes and deleterious alleles (linkage drag). Further, when R genes are bred one at a time into crop lines, the protection that they confer is often overcome within a few seasons by pathogen evolution. If several cloned R genes were available, it would be possible to pyramid R genes in a crop, which might provide more durable resistance. We describe a three-step method (MutRenSeq)-that combines chemical mutagenesis with exome capture and sequencing for rapid R gene cloning. We applied MutRenSeq to clone stem rust resistance genes Sr22 and Sr45 from hexaploid bread wheat. MutRenSeq can be applied to other commercially relevant crops and their relatives, including, for example, pea, bean, barley, oat, rye, rice and maize.


Assuntos
Clonagem Molecular/métodos , Resistência à Doença/genética , Genes de Plantas/genética , Mutagênese Sítio-Dirigida/métodos , Doenças das Plantas/genética , Plantas/genética , Melhoramento Genético/métodos , Doenças das Plantas/prevenção & controle , Plantas Geneticamente Modificadas/genética , Análise de Sequência de DNA/métodos
15.
J Appl Genet ; 57(4): 453-465, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27091460

RESUMO

Wild relatives, landraces and cultivars from different geographical regions have been demonstrated as the sources of genetic variation for resistance to rust diseases. This study involved assessment of diversity for resistance to three rust diseases among a set of Nordic spring wheat cultivars. These cultivars were tested at the seedling stage against several pathotypes of three rust pathogens in the greenhouse. All stage stem rust resistance genes Sr7b, Sr8a, Sr12, Sr15, Sr17, Sr23 and Sr30, and leaf rust resistance genes Lr1, Lr3a, Lr13, Lr14a, Lr16 and Lr20 were postulated either singly or in different combinations among these cultivars. A high proportion of cultivars were identified to carry linked rust resistance genes Sr15 and Lr20. Although 51 cultivars showed variation against Puccinia striiformis f. sp. tritici (Pst) pathotypes used in this study, results were not clearly contrasting to enable postulation of stripe rust resistance genes in these genotypes. Stripe rust resistance gene Yr27 was postulated in four cultivars and Yr1 was present in cultivar Zebra. Cultivar Tjalve produced low stripe rust response against all Pst pathotypes indicating the presence either of a widely effective resistance gene or combination of genes with compensating pathogenic specificities. Several cultivars carried moderate to high level of APR to leaf rust and stripe rust. Seedling stem rust susceptible cultivar Aston exhibited moderately resistant to moderately susceptible response, whereas other cultivars belonging to this class were rated moderately susceptible or higher. Molecular markers linked with APR genes Yr48, Lr34/Yr18/Sr57, Lr68 and Sr2 detected the presence of these genes in some genotypes.


Assuntos
Resistência à Doença/genética , Doenças das Plantas/genética , Triticum/genética , Austrália , Basidiomycota , Marcadores Genéticos , Variação Genética , Genótipo , Doenças das Plantas/microbiologia , Plântula/microbiologia , Triticum/microbiologia
17.
Nat Genet ; 47(12): 1494-8, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26551671

RESUMO

As there are numerous pathogen species that cause disease and limit yields of crops, such as wheat (Triticum aestivum), single genes that provide resistance to multiple pathogens are valuable in crop improvement. The mechanistic basis of multi-pathogen resistance is largely unknown. Here we use comparative genomics, mutagenesis and transformation to isolate the wheat Lr67 gene, which confers partial resistance to all three wheat rust pathogen species and powdery mildew. The Lr67 resistance gene encodes a predicted hexose transporter (LR67res) that differs from the susceptible form of the same protein (LR67sus) by two amino acids that are conserved in orthologous hexose transporters. Sugar uptake assays show that LR67sus, and related proteins encoded by homeoalleles, function as high-affinity glucose transporters. LR67res exerts a dominant-negative effect through heterodimerization with these functional transporters to reduce glucose uptake. Alterations in hexose transport in infected leaves may explain its ability to reduce the growth of multiple biotrophic pathogen species.


Assuntos
Resistência à Doença/genética , Proteínas de Transporte de Monossacarídeos/genética , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Triticum/genética , Triticum/microbiologia , Sequência de Aminoácidos , Ascomicetos/fisiologia , Dados de Sequência Molecular , Mutação/genética , Triticum/crescimento & desenvolvimento
18.
Theor Appl Genet ; 128(10): 2113-9, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26163768

RESUMO

KEY MESSAGE: A new stem rust resistance gene Sr49 was mapped to chromosome 5BL of wheat. Usefulness of the closely linked markers sun209 and sun479 for marker-assisted selection of Sr49 was demonstrated. Landrace AUS28011 (Mahmoudi), collected from Ghardimaou, Tunisia, produced low stem rust response against Australian pathotypes of Puccinia graminis f. sp. tritici (Pgt) carrying virulence for several stem rust resistance genes deployed in modern wheat cultivars. Genetic analysis based on a Mahmoudi/Yitpi F3 population indicated the involvement of a single all-stage stem rust resistance gene and it was temporarily named SrM. Bulked segregant analysis using multiplex-ready SSR technology located SrM on the long arm of chromosome 5B. Since there is no other all-stage stem rust resistance gene located in chromosome 5BL, SrM was permanently designated Sr49. The Mahmoudi/Yitpi F3 population was enhanced to generate F6 recombinant inbred line (RIL) population for detailed mapping of Sr49 using publicly available genomic resources. Markers sun209 and sun479 flanked Sr49 at 1.5 and 0.9 cM distally and proximally, respectively. Markers sun209 and sun479 amplified PCR products different than the Sr49-linked alleles in 146 and 145 common wheat cultivars, respectively. Six and seven cultivars, respectively, carried the resistance-linked marker alleles sun209 148bp and sun479 200bp ; however, none of the cultivars carried both resistance-linked alleles. These results demonstrated the usefulness of these markers for marker-assisted selection of Sr49 in breeding programs.


Assuntos
Basidiomycota , Mapeamento Cromossômico , Resistência à Doença/genética , Doenças das Plantas/genética , Triticum/genética , Alelos , Austrália , Cromossomos de Plantas , Genes de Plantas , Ligação Genética , Marcadores Genéticos , Genótipo , Padrões de Herança , Repetições de Microssatélites , Melhoramento Vegetal , Doenças das Plantas/microbiologia , Triticum/microbiologia , Tunísia
19.
Genome Biol ; 16: 48, 2015 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-25886949

RESUMO

BACKGROUND: Bread wheat is an allopolyploid species with a large, highly repetitive genome. To investigate the impact of selection on variants distributed among homoeologous wheat genomes and to build a foundation for understanding genotype-phenotype relationships, we performed population-scale re-sequencing of a diverse panel of wheat lines. RESULTS: A sample of 62 diverse lines was re-sequenced using the whole exome capture and genotyping-by-sequencing approaches. We describe the allele frequency, functional significance, and chromosomal distribution of 1.57 million single nucleotide polymorphisms and 161,719 small indels. Our results suggest that duplicated homoeologous genes are under purifying selection. We find contrasting patterns of variation and inter-variant associations among wheat genomes; this, in addition to demographic factors, could be explained by differences in the effect of directional selection on duplicated homoeologs. Only a small fraction of the homoeologous regions harboring selected variants overlapped among the wheat genomes in any given wheat line. These selected regions are enriched for loci associated with agronomic traits detected in genome-wide association studies. CONCLUSIONS: Evidence suggests that directional selection in allopolyploids rarely acted on multiple parallel advantageous mutations across homoeologous regions, likely indicating that a fitness benefit could be obtained by a mutation at any one of the homoeologs. Additional advantageous variants in other homoelogs probably either contributed little benefit, or were unavailable in populations subjected to directional selection. We hypothesize that allopolyploidy may have increased the likelihood of beneficial allele recovery by broadening the set of possible selection targets.


Assuntos
Cromossomos de Plantas/genética , Genoma de Planta , Poliploidia , Triticum/genética , Mapeamento Cromossômico , Exoma , Frequência do Gene , Genótipo , Haplótipos , Polimorfismo de Nucleotídeo Único , Seleção Genética
20.
Nat Plants ; 1: 15186, 2015 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-27251721

RESUMO

We identify the wheat stem rust resistance gene Sr50 (using physical mapping, mutation and complementation) as homologous to barley Mla, encoding a coiled-coil nucleotide-binding leucine-rich repeat (CC-NB-LRR) protein. We show that Sr50 confers a unique resistance specificity different from Sr31 and other genes on rye chromosome 1RS, and is effective against the broadly virulent Ug99 race lineage. Extensive haplotype diversity at the rye Sr50 locus holds promise for mining effective resistance genes.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA