SSR Genotyping Research Articles

Evaluation of the Spore Dispersal in Rice Blast Field Population by SSR Genotyping

Evaluation of the Spore Dispersal in Rice Blast Field Population by SSR Genotyping

Genetic diversity of the wx flanking region in rice landraces in northern Laos.

A glutinous texture of endosperm is one of the important traits of rice (Oyza sativa L.). Northern Laos is known as a center of glutinous rice diversity. We genotyped INDEL, SSR and SNP markers in a sample of 297 rice landraces collected in northern Laos. These glutinous varieties were confirmed to share a loss-of-function mutation in Granule bound starch synthase I (Wx). INDEL markers revealed a high frequency of recombinant genotypes between indica and japonica. Principal component analysis using SSR genotypes of Wx flanking region revealed that glutinous indica landraces were scattered between non-glutinous indica and glutinous-japonica types. High ratios of heterozygosity were found especially in glutinous indica. Haplotype analysis using SNP markers around Wx locus revealed that glutinous indica landraces would have a few chromosome segments of glutinous japonica. Frequent recombinations were confirmed outside of this region in glutinous indica. This intricate genetic structure of landraces suggested that glutinous indica landraces in Laos were generated through repeated natural crossing with glutinous-japonica landraces and severe selection by local farmers.

Transcriptome-derived evidence supports recent polyploidization and a major phylogeographic division in Trithuria submersa (Hydatellaceae, Nymphaeales).

Relatively little is known about species-level genetic diversity in flowering plants outside the eudicots and monocots, and it is often unclear how to interpret genetic patterns in lineages with whole-genome duplications. We addressed these issues in a polyploid representative of Hydatellaceae, part of the water-lily order Nymphaeales. We examined a transcriptome of Trithuria submersa for evidence of recent whole-genome duplication, and applied transcriptome-derived microsatellite (expressed-sequence tag simple-sequence repeat (EST-SSR)) primers to survey genetic variation in populations across its range in mainland Australia. A transcriptome-based Ks plot revealed at least one recent polyploidization event, consistent with fixed heterozygous genotypes representing underlying sets of homeologous loci. A strong genetic division coincides with a trans-Nullarbor biogeographic boundary. Patterns of 'allelic' variation (no more than two variants per EST-SSR genotype) and recently published chromosomal evidence are consistent with the predicted polyploidization event and substantial homozygosity underlying fixed heterozygote SSR genotypes, which in turn reflect a selfing mating system. The Nullarbor Plain is a barrier to gene flow between two deep lineages of T.submersa that may represent cryptic species. The markers developed here should also be useful for further disentangling species relationships, and provide a first step towards future genomic studies in Trithuria.

Strategies for a successful plant invasion: the reproduction of Phragmites australis in north‐eastern North America

Summary Knowing the relative contribution of vegetative propagation and sexual reproduction to the dispersal and establishment of exotic plants is crucial for devising efficient control strategies. This is particularly true for the common reed (Phragmites australis), one of the most invasive species in North America. For the first time, we combined in situ field observations and genetic evidence, based on two genotyping techniques, that is microsatellite markers (SSR) and genotyping by sequencing (GBS), to determine the propagation strategies of this invader at its northern distribution limit in North America and especially in roadside ditches. Field observations revealed that, in a region where the common reed is already abundant, both seeds and plant fragments contributed to the establishment of new populations. Newly established individuals originated mostly (84%) from seeds rather than fragments, but a larger proportion of individuals originating from fragments survived the second year compared to seedlings. High genetic diversity among marsh and roadside common reed stands indicated the prime role of sexual reproduction for dispersal. The vast majority of genotypes were found in only one stand; such high genetic variability can only be explained by sexual reproduction. Half the surveyed stands comprised a single clone, suggesting that local expansion mainly occurred vegetatively. As the small proportion of SSR genotypes initially thought to be common between distant stands proved to be distinct (as revealed by GBS data), it is likely that all the stands examined were initially founded by genetically distinct individuals. Synthesis. Our study suggests that long‐distance dispersal by seeds is important for the common reed, in marshes and roadsides, while both seeds and plant fragments contribute to short‐distance dispersal along roads, at least in regions where the species is already abundant. The success of this invader in North America seems to be attributable to a reproduction strategy combining the advantages of sexuality with those of vegetative propagation. Moreover, this study shows that the GBS approach strongly reduces uncertainties associated with the use of a limited number of markers. This approach is especially valuable for ecologists dealing with an ever‐increasing number of invaders, of which few have identified microsatellite markers.

The geographic mosaic of herbicide resistance evolution in the common morning glory, Ipomoea purpurea: Evidence for resistance hotspots and low genetic differentiation across the landscape.

Strong human-mediated selection via herbicide application in agroecosystems has repeatedly led to the evolution of resistance in weedy plants. Although resistance can occur among separate populations of a species across the landscape, the spatial scale of resistance in many weeds is often left unexamined. We assessed the potential that resistance to the herbicide glyphosate in the agricultural weed Ipomoea purpurea has evolved independently multiple times across its North American range. We examined both adaptive and neutral genetic variations in 44 populations of I. purpurea by pairing a replicated dose–response greenhouse experiment with SSR genotyping of experimental individuals. We uncovered a mosaic pattern of resistance across the landscape, with some populations exhibiting high-survival postherbicide and other populations showing high death. SSR genotyping revealed little evidence of isolation by distance and very little neutral genetic structure associated with geography. An approximate Bayesian computation (ABC) analysis uncovered evidence for migration and admixture among populations before the widespread use of glyphosate rather than the very recent contemporary gene flow. The pattern of adaptive and neutral genetic variations indicates that resistance in this mixed-mating weed species appears to have evolved in independent hotspots rather than through transmission of resistance alleles across the landscape.

Molecular and Cytogenetic Characterization of Wild Musa Species.

The production of bananas is threatened by rapid spreading of various diseases and adverse environmental conditions. The preservation and characterization of banana diversity is essential for the purposes of crop improvement. The world's largest banana germplasm collection maintained at the Bioversity International Transit Centre (ITC) in Belgium is continuously expanded by new accessions of edible cultivars and wild species. Detailed morphological and molecular characterization of the accessions is necessary for efficient management of the collection and utilization of banana diversity. In this work, nuclear DNA content and genomic distribution of 45S and 5S rDNA were examined in 21 diploid accessions recently added to ITC collection, representing both sections of the genus Musa. 2C DNA content in the section Musa ranged from 1.217 to 1.315 pg. Species belonging to section Callimusa had 2C DNA contents ranging from 1.390 to 1.772 pg. While the number of 45S rDNA loci was conserved in the section Musa, it was highly variable in Callimusa species. 5S rRNA gene clusters were found on two to eight chromosomes per diploid cell. The accessions were genotyped using a set of 19 microsatellite markers to establish their relationships with the remaining accessions held at ITC. Genetic diversity done by SSR genotyping platform was extended by phylogenetic analysis of ITS region. ITS sequence data supported the clustering obtained by SSR analysis for most of the accessions. High level of nucleotide diversity and presence of more than two types of ITS sequences in eight wild diploids pointed to their origin by hybridization of different genotypes. This study significantly expands the number of wild Musa species where nuclear genome size and genomic distribution of rDNA loci is known. SSR genotyping identified Musa species that are closely related to the previously characterized accessions and provided data to aid in their classification. Sequence analysis of ITS region provided further information about evolutionary relationships between individual accessions and suggested that some of analyzed accessions were interspecific hybrids and/or backcross progeny.

Population genetic analysis of Phytophthora infestans in northwestern China

Late blight caused by Phytophthora infestans is the most devastating disease of potato worldwide. To understand the P. infestans population structure and dynamics in northwestern China, 959 single‐lesion isolates were purified in three consecutive years (2009–2011) and were characterized for mating type, pathotype, mtDNA haplotype and molecular variation at eight SSR loci. The results showed that the distribution of mating types changed significantly over years, with self‐fertile isolates dominant in 2010 and 2011. SSR genotyping distinguished 959 isolates into 151 genotypes, and association analysis indicated that P. infestans populations in 2010 and 2011 were strictly asexual while in 2009 they showed signs of sexual reproduction. Population analysis showed that the majority of genetic variation was within P. infestans populations. Isolates sharing identical SSR genotypes were detected in distant regions, indicating that migration of P. infestans could have occurred between regions. Pathogenicity assays on a set of potato differential lines containing R1 to R11 resistance genes detected four pathotypes from 74 selected isolates, with the pathotype virulent against all 11 R genes being dominant. Three mtDNA haplotypes (Ia, IIa, IIb) were detected with Ia being dominant among 507 isolates examined. Phylogenetic analysis indicated that P. infestans populations in northwestern China are distant from European lineages including 13‐A2 (blue‐13) at the time of this survey. The results have implications for the trade of healthy seed tubers as a means of managing late blight.

Use of morphological traits and microsatellite markers to characterize the Tunisian cultivated and wild figs (Ficus carica L.)

We used 8 morphological traits and 17 simple sequence repeats loci to characterize 71 cultivated and wild Tunisian fig trees (Ficus carica L.). Significant morphological differences were inferred from leaf traits. The statistical analysis showed two major fig groups that indicated a common morphological basis. A total of 74 SSR alleles was revealed, defining 63 unique multilocus genotypes indicating a substantial genetic diversity. Based on multilocus SSR genotypes an identification key was established using MFC30, MFC3, MFC11 and MFC19 loci to identify figs. Analysis of variance components of linkage disequilibrium shown that among 136 pairs of loci, 32 present a significant gametic disequilibrium. The parameter D′2IS (0.1284) was greater than D′2ST (0.0079), a pointer of close to zero variance in total simple, and consequently the more pronounced independence of the 17 SSR loci. The majority of Ohta's variance components of linkage disequilibrium followed a pattern caused by genetic drift or a non-systematic disequilibrium profiles and natural selection occurs only for LMFC24-MFC8 pair loci in cultivated figs. Our results suggest that the morphological and SSR markers are suitable to characterize figs and should be recommended in conservation management strategy.

Congruence of microsatellite and mitochondrial DNA variation in acrobat ants (Crematogaster subgenus Decacrema, Formicidae: Myrmicinae) inhabiting Macaranga (Euphorbiaceae) myrmecophytes.

A previously reported mitochondrial DNA (mtDNA) phylogeny of Crematogaster (subgenus Decacrema) ants inhabiting Macaranga myrmecophytes indicated that the partners diversified synchronously and their specific association has been maintained for 20 million years. However, the mtDNA clades did not exactly match morphological species, probably owing to introgressive hybridization among younger species. In this study, we determined the congruence between nuclear simple sequence repeat (SSR, also called microsatellite) genotyping and mtDNA phylogeny to confirm the suitability of the mtDNA phylogeny for inferring the evolutionary history of Decacrema ants. Analyses of ant samples from Lambir Hills National park, northeastern Borneo, showed overall congruence between the SSR and mtDNA groupings, indicating that mtDNA markers are useful for delimiting species, at least at the local level. We also found overall high host-plant specificity of the SSR genotypes of Decacrema ants, consistent with the specificity based on the mtDNA phylogeny. Further, we detected cryptic genetic assemblages exhibiting high specificity toward particular plant species within a single mtDNA clade. This finding, which may be evidence for rapid ecological and genetic differentiation following a host shift, is a new insight into the previously suggested long-term codiversification of Decacrema ants and Macaranga plants.

Construction of a core collection and evaluation of genetic resources for Cryptomeria japonica (Japanese cedar)

In order to improve the accessibility of genetic resources, a core collection needs to be constructed and appropriately evaluated. For Cryptomeria japonica, the most important forestry species in Japan, we constructed a core collection derived from 3,203 plus trees. First, genetic redundancy was removed based on SSR genotypes from the plus tree population. One diploid accession from each of the 539 groups that were identified using information on the original growing location was then selected considering the conservation conditions. We defined this population composed of 539 individuals as a core collection for C. japonica, and then evaluated the collection status of this core collection from multiple viewpoints. This core collection proved to contain on average one entry selected per 10 km radius (314 km2) from 10 × 10 km grid squares with an area of more than 40 % covered with C. japonica, and covered more than 85 % retention of all 12 environmental factors affecting plus trees, while maintaining almost the same genetic diversity as the complete set of plus trees. These methods of evaluation from multiple viewpoints, using a geographic information system and genetic markers, were efficient in determining whether the collection of resources was complete, and, if not, where additional efforts for balancing a deficit should be devoted.

Population differentiation of Thai fragrant rice variety revealed by SSR marker analysis

This study aims to survey an allele badh2 , an 8 bp deletion in exon 7 of the fgr gene, in a representative rice collection of two traditional fragrant rice varieties, Hohm Nangnuan and Hohm Thung, grown in the northeastern region of Thailand. The study also determines the population genetic structure of these two traditional varieties by using 13 SSR markers surrounding the aroma loci mapped on chromosome 8. It was found that rice accessions of Hohm Nangnuan from Mahasarakham, Ubon Ratchathani (type 2), Yasothon, and Sakon Nakhon provinces showed fragrant genotypes ( badh2/badh2) , while Hohm Nangnuan type 1 from Ubon Ratchathani showed the non-fragrant genotype ( Badh2/Badh2 ). For the Hohm Thung variety from Ubon Ratchathani province, all rice accessions with the rice straw husk used in this experiment carried the fragrant genotype, whereas rice accessions with the rice brown husk carried the non-fragrant genotype. Based on the data of SSR genotype over the 13 SSR loci, the STRUCTURE simulation illustrates a spatial pattern that corresponds to their name.

Diversity of Oxalis tuberosa Molina: a comparison between AFLP and microsatellite markers

Traditional crops contribute to food security and agroecological sustainability, but their diversity is increasingly threatened by complex interplays of local and global sociocultural and economic change. Molecular markers are powerful tools to measure and characterize this diversity, and comparisons among different molecular marker systems are necessary to assess their appropriateness in different research contexts. Using a common sample set, we compare amplified fragment length polymorphism (AFLP) and microsatellite (simple sequence repeats; SSRs) techniques to assess their utility in research on the Andean tuber crop oca (Oxalis tuberosa Molina, Oxalidaceae). We find that 26 of 27 individuals have distinct AFLP genotypes, and all 27 individuals have distinct SSR genotypes. Both markers systems cluster samples in agreement with morphotype groups and separate clusters with similar strength, but more variation occurs within AFLP-based clusters than within SSR-based clusters. In addition, correlation between marker systems of pairwise distances is positive and significant (R = 0.831, p = 0.001). Ultimately, we discuss each system’s advantages and disadvantages for future oca diversity research.

MOLECULAR CHARACTERIZATION OF THE GRAPEVINE GERMPLASM COLLECTION HELD AT THE FONDAZIONE EDMUND MACH

Growing scientific interest in the genetic diversity of grapevine, together with the need to improve the organization of conserved materials and streamline manage-ment costs has given rise to a project aimed at characterizing all the germplasm maintained by FEM-IASMA. In an initial molecular analysis, one plant of each accession was tested at 10 microsatellite loci (SSR). Comparison of the profiles obtained allowed the genotypes present to be identified and hence the number of accessions to undergo further investigation to be reduced. The extension of genotyping to 12 other SSR loci confirmed the consistency of the collection?s gene pool. Using assignment experiments, comparisons with international databases and ampelo¬graphic verification, grape cultivars with the same SSR profile are attributed to cases of synonymy or denomination errors. The most interesting phenotypic variations amongst plants with an identical SSR genotype will be selected for conservation. The set of accessions with a non-redundant genotype is the collection?s main source of genetic diversity. Regarding this material, intense genotyping of hundreds of SNP loci is underway in order to identify appropriate core collections for future association studies. Some of the characteristics emerging from this study and other evaluations of the collection?s contents are presented.

Development of a rapid multiplex SSR genotyping method to study populations of the fungal plant pathogen Zymoseptoria tritici.

BackgroundZymoseptoria tritici is a hemibiotrophic ascomycete fungus causing leaf blotch of wheat that often decreases yield severely. Populations of the fungus are known to be highly diverse and poorly differentiated from each other. However, a genotyping tool is needed to address further questions in large collections of isolates, regarding regional population structure, adaptation to anthropogenic selective pressures, and dynamics of the recently discovered accessory chromosomes. This procedure is limited by costly and time-consuming simplex PCR genotyping. Recent development of genomic approaches and of larger sets of SSRs enabled the optimization of microsatellite multiplexing.FindingsWe report here a reliable protocol to amplify 24 SSRs organized in three multiplex panels, and covering all Z. tritici chromosomes. We also propose an automatic allele assignment procedure, which allows scoring alleles in a repeatable manner across studies and laboratories. All together, these tools enabled us to characterize local and worldwide populations and to calculate diversity indexes consistent with results reported in the literature.ConclusionThis easy-to-use, accurate, repeatable, economical, and faster technical strategy can provide useful genetic information for evolutionary inferences concerning Z. tritici populations. Moreover, it will facilitate the comparison of studies from different scientific groups.

Occurrence of a Spontaneous Triploid Progeny from Crosses between Diploid Asparagus (Asparagus officinalis L.) Plants and Its Origin Determined by SSR Markers

The origin of a spontaneous triploid asparagus plant from crosses of 2x × 2x was investigated by SSR and flow cytometric analyses. One hundred and twenty-four progeny were obtained from crosses between a diploid female ‘Gold Schatz’ and a diploid male ‘Hokkai 100’. SSR analysis proved that two and one genes were transmitted from the maternal and paternal parents, respectively, at each SSR locus of one progeny, 07M-61, whereas one gene each was from the female and male parents in the other diploid progeny. Triploidy of 07M-61 was confirmed by flow cytometric analysis. It was suggested that the triploid plant was derived from fertilization between an unreduced egg and reduced sperm nuclei, given its SSR genotypes. It was also suggested that the unreduced maternal gamete was derived from first division restitution (FDR) or second division restitution (SDR) with chiasma occurrence during meiosis. There were no noticeable morphological differences between the triploid and diploid progeny.

Analysis and Optimization of Bulk DNA Sampling with Binary Scoring for Germplasm Characterization

The strategy of bulk DNA sampling has been a valuable method for studying large numbers of individuals through genetic markers. The application of this strategy for discrimination among germplasm sources was analyzed through information theory, considering the case of polymorphic alleles scored binarily for their presence or absence in DNA pools. We defined the informativeness of a set of marker loci in bulks as the mutual information between genotype and population identity, composed by two terms: diversity and noise. The first term is the entropy of bulk genotypes, whereas the noise term is measured through the conditional entropy of bulk genotypes given germplasm sources. Thus, optimizing marker information implies increasing diversity and reducing noise. Simple formulas were devised to estimate marker information per allele from a set of estimated allele frequencies across populations. As an example, they allowed optimization of bulk size for SSR genotyping in maize, from allele frequencies estimated in a sample of 56 maize populations. It was found that a sample of 30 plants from a random mating population is adequate for maize germplasm SSR characterization. We analyzed the use of divided bulks to overcome the allele dilution problem in DNA pools, and concluded that samples of 30 plants divided into three bulks of 10 plants are efficient to characterize maize germplasm sources through SSR with a good control of the dilution problem. We estimated the informativeness of 30 SSR loci from the estimated allele frequencies in maize populations, and found a wide variation of marker informativeness, which positively correlated with the number of alleles per locus.

Radiation of the Nod‐independent Aeschynomene relies on multiple allopolyploid speciation events

• The semi-aquatic legumes belonging to the genus Aeschynomene constitute a premium system for investigating the origin and evolution of unusual symbiotic features such as stem nodulation and the presence of a Nod-independent infection process. This latter apparently arose in a single Aeschynomene lineage. But how this unique Nod-independent group then radiated is not yet known. • We have investigated the role of polyploidy in Aeschynomene speciation via a case study of the pantropical A. indica and then extended the analysis to the other Nod-independent species. For this, we combined SSR genotyping, genome characterization through flow cytometry, chromosome counting, FISH and GISH experiments, molecular phylogenies using ITS and single nuclear gene sequences, and artificial hybridizations. • These analyses demonstrate the existence of an A. indica polyploid species complex comprising A. evenia (C. Wright) (2n = 2x = 20), A. indica L. s.s. (2n = 4x = 40) and a new hexaploid form (2n = 6x = 60). This latter contains the two genomes present in the tetraploid (A. evenia and A. scabra) and another unidentified genome. Two other species, A. pratensis and A. virginica, are also shown to be of allopolyploid origin. • This work reveals multiple hybridization/polyploidization events, thus highlighting a prominent role of allopolyploidy in the radiation of the Nod-independent Aeschynomene.

Molecular analysis of genetic diversity, population structure and inbreeding level of the Italian Lipizzan horse

In this study, we examine the population structure and inbreeding level of the Italian Lipizzan horse breed by means of AFLP fingerprinting and SSR genotyping. A total of 245 AFLP marker alleles were scored across all horses (n=140) living in the Italian Lipizzan stud in 2007, and microsatellite analysis was performed on all mares (n=42) and stallions (n=7) by genotyping at 30 SSR marker loci. A total of 53 (21.6%) AFLP marker alleles were scored as polymorphic among the animals, with a mean frequency of 0.722. Based on this subset of markers, 123 animals were assigned to three distinct subgroups of 44, 41 and 38 animals, respectively, each one showing a within-subgroup mean Dice's genetic similarity around 86% (standard error<0.3%), whereas the remaining 17 animals that displayed an admixed ancestry (membership<45%) were clustered apart, with a between-subgroup genetic similarity spanning from 80% to 83%. All animals could be discriminated from each other on the basis of multi-locus DNA fingerprints. However, only 6% of the genetic variation was found among subgroups, as supported by the low fixation index Fst=0.058. In the mares and stallions, a total number of 146 marker alleles were detected across the assayed SSR loci, with a mean marker allele frequency of 0.485 and an observed and effective number of alleles per locus of 4.710 and 2.921, respectively. The Nei's unbiased heterozygosity for the Italian Lipizzan horse breed was equal to H=63.5% and the Wright's inbreeding coefficient had an average value of Fis=−0.133, suggesting an excess of heterozygosity. Significant (P<0.01) pair-wise linkage disequilibria between AFLP marker alleles as well as between SSR marker alleles were found in the whole Lipizzan population. It was found that mating plan optimization could reduce the average relatedness to 0.619, a lower value than that obtained by casual unions between stallions and mares (0.740). The findings described here will be useful for the indirect selection of animals based on markers linked to traits of interest and for the assessment of conservation priorities and strategies.

High Resolution Melting Analysis Is a More Sensitive and Effective Alternative to Gel-Based Platforms in Analysis of SSR – An Example in Citrus

High resolution melting curve analysis (HRM) has been used as an efficient, accurate and cost-effective tool to detect single nucleotide polymorphisms (SNPs) or insertions or deletions (INDELs). However, its efficiency, accuracy and applicability to discriminate microsatellite polymorphism have not been extensively assessed. The traditional protocols used for SSR genotyping include PCR amplification of the DNA fragment and the separation of the fragments on electrophoresis-based platform. However, post-PCR handling processes are laborious and costly. Furthermore, SNPs present in the sequences flanking repeat motif cannot be detected by polyacrylamide-gel-electrophoresis based methods. In the present study, we compared the discriminating power of HRM with the traditional electrophoresis-based methods and provided a panel of primers for HRM genotyping in Citrus. The results showed that sixteen SSR markers produced distinct polymorphic melting curves among the Citrus spp investigated through HRM analysis. Among those, 10 showed more genotypes by HRM analysis than capillary electrophoresis owing to the presence of SNPs in the amplicons. For the SSR markers without SNPs present in the flanking region, HRM also gave distinct melting curves which detected same genotypes as were shown in capillary electrophoresis (CE) analysis. Moreover, HRM analysis allowed the discrimination of most of the 15 citrus genotypes and the resulting genetic distance analysis clustered them into three main branches. In conclusion, it has been approved that HRM is not only an efficient and cost-effective alternative of electrophoresis-based method for SSR markers, but also a method to uncover more polymorphisms contributed by SNPs present in SSRs. It was therefore suggested that the panel of SSR markers could be used in a variety of applications in the citrus biodiversity and breeding programs using HRM analysis. Furthermore, we speculate that the HRM analysis can be employed to analyse SSR markers in a wide range of applications in all other species.

Inheritance and molecular mapping of a gene conferring seedling resistance against Puccinia hordei in the barley cultivar Ricardo

Genetic studies were undertaken to determine the inheritance and genomic location of uncharacterised seedling resistance to leaf rust, caused by Puccinia hordei, in the barley cultivar Ricardo. The resistance was shown to be conferred by a single dominant gene, which was tentatively designated RphRic. Bulk segregant analysis (BSA) and genetic mapping of an F(3) mapping population using multiplex-ready SSR genotyping and Illumina GoldenGate SNP assay located RphRic in chromosome 4H. Given that this is the first gene for leaf rust resistance mapped on chromosome 4H, it was designated Rph21. The presence of an additional gene, Rph2, in Ricardo, was confirmed by the test of allelism. The seedling gene Rph21 has shown effectiveness against all Australian pathotypes of P. hordei tested since at least 1992 and hence represents a new and useful source of resistance to this pathogen.