Molecular and genetic characterization of barley mutants and genetic mapping of mutant rpr2 required for Rpg1-mediated resistance against stem rust.

This study describes the generation, screening, genetic and molecular characterization, and high-resolution mapping of barley mutants susceptible to stem rust ( Puccinia graminis f. sp. tritici ) races MCCF and HKHJ.

Sequencing of 15 622 gene-bearing BACs clarifies the gene-dense regions of the barley genome.

Barley (Hordeum vulgare L.) possesses a large and highly repetitive genome of 5.1 Gb that has hindered the development of a complete sequence.

The rpg4-mediated resistance to wheat stem rust (Puccinia graminis) in barley (Hordeum vulgare) requires Rpg5, a second NBS-LRR gene, and an actin depolymerization factor.

The rpg4 gene confers recessive resistance to several races of wheat stem rust (Puccinia graminis f. sp. tritici) and Rpg5 provides dominant resistance against isolates of the rye stem rust (P.

Concerted action of two avirulent spore effectors activates Reaction to Puccinia graminis 1 (Rpg1)-mediated cereal stem rust resistance.

The barley stem rust resistance gene Reaction to Puccinia graminis 1 (Rpg1), encoding a receptor-like kinase, confers durable resistance to the stem rust pathogen Puccinia graminis f. sp. tritici.

Polymorphic nuclear gene sequences indicate a novel genome donor in the polyploid genus Thinopyrum.

For decades, the wheatgrass genus Thinopyrum has been of interest to plant breeders as a source of genes that confer competitive traits. This genus has been a considerable challenge to plant systematists because of the impacts of polyploidization on the evolution of this group. This study was aimed to augment existing cytogenetic data with a sequence-based investigation of the genomes of these species.

Stem rust spores elicit rapid RPG1 phosphorylation.

Stem rust threatens cereal production worldwide. Understanding the mechanism by which durable resistance genes, such as Rpg1, function is critical. We show that the RPG1 protein is phosphorylated within 5 min by exposure to spores from avirulent but not virulent races of stem rust.

A synteny map and disease resistance gene comparison between barley and the model monocot Brachypodium distachyon.

Grass species have coevolved with current economically important crop pathogens over millions of years. During this time, speciation of current domestic crops has occurred, resulting in related yet divergent genomes. Here, we present a synteny map between the crop species Hordeum vulgare and the recently sequenced Brachypodium distachyon genome, focusing on regions known to harbor important barley disease resistance genes.

Development and implementation of high-throughput SNP genotyping in barley.

Background: High density genetic maps of plants have, nearly without exception, made use of marker datasets containing missing or questionable genotype calls derived from a variety of genic and non-genic or anonymous markers, and been presented as a single linear order of genetic loci for each linkage group. The consequences of missing or erroneous data include falsely separated markers, expansion of cM distances and incorrect marker order. These imperfections are amplified in consensus maps and problematic when fine resolution is critical including comparative genome analyses and map-based cloning.

Resistance to stem rust race TTKSK maps to the rpg4/Rpg5 complex of chromosome 5H of barley.

Race TTKSK (Ug99) of the wheat stem rust pathogen (Puccinia graminis f. sp. tritici) is a serious threat to both wheat and barley production worldwide because of its wide virulence on many cultivars and rapid spread from eastern Africa.

The rpg4/Rpg5 stem rust resistance locus in barley: resistance genes and cytoskeleton dynamics.

Two closely linked resistance genes, rpg4 and Rpg5, conferring resistance to several races of Puccinia graminis, were cloned and characterized. The Rpg5 gene confers resistance to an isolate of Puccinia graminis f. sp.

Genetic and physical mapping of a high recombination region on chromosome 7H(1) in barley.

Approaches utilizing microlinearity between related species allow for the identification of syntenous regions and orthologous genes. Within the barley Chromosome 7H(1) is a region of high recombination flanked by molecular markers cMWG703 and MWG836. We present the constructed physical contigs linked to molecular markers across this region using bacterial artificial chromosomes (BAC) from the cultivar Morex.

Towards systems genetic analyses in barley: Integration of phenotypic, expression and genotype data into GeneNetwork.

Background: A typical genetical genomics experiment results in four separate data sets; genotype, gene expression, higher-order phenotypic data and metadata that describe the protocols, processing and the array platform. Used in concert, these data sets provide the opportunity to perform genetic analysis at a systems level. Their predictive power is largely determined by the gene expression dataset where tens of millions of data points can be generated using currently available mRNA profiling technologies.

A cation/proton-exchanging protein is a candidate for the barley NecS1 gene controlling necrosis and enhanced defense response to stem rust.

We characterized three lesion mimic necS1 (necrotic Steptoe) mutants, induced by fast neutron (FN) treatment of barley cultivar Steptoe. The three mutants are recessive and allelic. When infected with Puccinia graminis f.

Allele sequencing of the barley stem rust resistance gene Rpg1 identifies regions relevant to disease resistance.

The stem rust resistance gene Rpg1 has protected North American barley cultivars from significant yield losses for over 65 years. The remarkable durability of this gene warrants further study as to its possible origin and allelic variation. Eight Swiss barley (Hordeum vulgare) landraces and eight wild barley (H.

The stem rust resistance gene Rpg5 encodes a protein with nucleotide-binding-site, leucine-rich, and protein kinase domains.

We isolated the barley stem rust resistance genes Rpg5 and rpg4 by map-based cloning. These genes are colocalized on a 70-kb genomic region that was delimited by recombination. The Rpg5 gene consists of an unusual structure encoding three typical plant disease resistance protein domains: nucleotide-binding site, leucine-rich repeat, and serine threonine protein kinase.

Exploiting regulatory variation to identify genes underlying quantitative resistance to the wheat stem rust pathogen Puccinia graminis f. sp. tritici in barley.

We previously mapped mRNA transcript abundance traits (expression-QTL or eQTL) using the Barley1 Affymetrix array and 'whole plant' tissue from 139 progeny of the Steptoe x Morex (St/Mx) reference barley mapping population. Of the 22,840 probesets (genes) on the array, 15,987 reported transcript abundance signals that were suitable for eQTL analysis, and this revealed a genome-wide distribution of 23,738 significant eQTLs. Here we have explored the potential of using these mRNA abundance eQTL traits as surrogates for the identification of candidate genes underlying the interaction between barley and the wheat stem rust fungus Puccinia graminis f.

Parallel expression profiling of barley-stem rust interactions.

The dominant barley stem rust resistance gene Rpg1 confers resistance to many but not all pathotypes of the stem rust fungus Puccinia graminis f. sp. tritici (Pgt).

Proteolysis of the barley receptor-like protein kinase RPG1 by a proteasome pathway is correlated with Rpg1-mediated stem rust resistance.

In plants, disease resistance mediated by the gene-for-gene mechanism involves the recognition of specific effector molecules produced by the pathogen either directly or indirectly by the resistance-gene products. This recognition triggers a series of signals, thereby serving as a molecular switch in regulating defense mechanisms by the plants. To understand the mechanism of action of the barley stem rust resistance gene Rpg1, we investigated the fate of the RPG1 protein in response to infection with the stem rust fungus, Puccinia graminis f.

A high-density consensus map of barley linking DArT markers to SSR, RFLP and STS loci and agricultural traits.

Background: Molecular marker technologies are undergoing a transition from largely serial assays measuring DNA fragment sizes to hybridization-based technologies with high multiplexing levels. Diversity Arrays Technology (DArT) is a hybridization-based technology that is increasingly being adopted by barley researchers. There is a need to integrate the information generated by DArT with previous data produced with gel-based marker technologies.

The barley serine/threonine kinase gene Rpg1 providing resistance to stem rust belongs to a gene family with five other members encoding kinase domains.

The barley (Hordeum vulgare L.) stem rust (Puccinia graminis f. sp.

Rpr1, a gene required for Rpg1-dependent resistance to stem rust in barley.

Rpg1 is a stem rust resistance gene that has protected barley from severe losses for over 60 years in the US and Canada. It confers resistance to many, but not all, pathotypes of the stem rust fungus Puccinia graminis f. sp.

Subcellular localization and functions of the barley stem rust resistance receptor-like serine/threonine-specific protein kinase Rpg1.

The Rpg1 gene confers resistance to many pathotypes of the stem rust fungus Puccinia graminis f. sp. tritici and has protected barley from serious disease losses for over 60 years.

An atlas of gene expression from seed to seed through barley development.

Assaying relative and absolute levels of gene expression in a diverse series of tissues is a central step in the process of characterizing gene function and a necessary component of almost all publications describing individual genes or gene family members. However, throughout the literature, such studies lack consistency in genotype, tissues analyzed, and growth conditions applied, and, as a result, the body of information that is currently assembled is fragmented and difficult to compare between different studies. The development of a comprehensive platform for assaying gene expression that is available to the entire research community provides a major opportunity to assess whole biological systems in a single experiment.

Barley necrotic locus nec1 encodes the cyclic nucleotide-gated ion channel 4 homologous to the Arabidopsis HLM1.

Barley homolog of the Arabidopsis necrotic (disease lesion mimic) mutant HLM1 that encodes the cyclic nucleotide-gated ion channel 4 was cloned. Barley gene was mapped genetically to the known necrotic locus nec1 and subsequent sequence analysis identified mutations in five available nec1 alleles confirming barley homolog of Arabidopsis HLM1 as the NEC1 gene. Two fast neutron (FN) induced mutants had extensive deletions in the gene, while two previously described nec1 alleles had either a STOP codon in exon 1 or a MITE insertion in intron 2 which caused alternative splicing, frame shift and production of a predicted non-functional protein.