G.J. Platz

Queensland Government · Department of Agriculture and Fisheries

Net form of net blotch caused by Pyrenophora teres f. teres (Ptt) is a major foliar disease of barley (Hordeum vulgare) worldwide. Knowledge of the evolution of P. teres f. teres pathogen populations is important for development of durable host‐plant resistance. This study was conducted to investigate changes in genetic structure of a Ptt populatio...

We assembled an international barley panel comprising 282 entries from 26 countries with various levels of field resistance to leaf rust caused by Puccinia hordei. The panel was screened for leaf rust response with an array of pathotypes at the seedling stage, and at the adult plant stage in multiple environments (2013-2015) in Aus-tralia and Urugu...

Pyrenophora teres f. teres (Ptt) and P. teres f. maculata (Ptm) cause net and spot form of net blotch of barley (Hordeum vulgare L.), respectively. Both pathogens co-exist in barley fields and each can reproduce sexually, resulting in hybridisation and potential generation of novel virulences that could overcome barley host resistances. In this stu...

Net form of net blotch (NFNB) caused by the fungus Pyrenophora teres f. teres is an economically important foliar disease of barley (Hordeum vulgare) in southern and eastern Africa. Little attention has been given to disease resistance breeding, and knowledge about the presence of NFNB resistance in breeding lines is limited. Deploying resistance i...

Key message: Thirteen potentially new leaf rust resistance loci were identified in a Vavilov wheat diversity panel. We demonstrated the potential of allele stacking to strengthen resistance against this important pathogen. Leaf rust (LR) caused by Puccinia triticina is an important disease of wheat (Triticum aestivum L.), and the deployment of gen...

Host genetic resistance is the most effective and sustainable means of managing tan spot or yellow spot of wheat. The disease is becoming increasingly problematic due to the adoption of minimum tillage practices, evolution of effector-mediated pathogenicity, and widespread cultivation of susceptible cultivars from a narrow genetic base. This highli...

Key message: Genome-wide association studies of barley breeding populations identified candidate minor genes for pairing with the adult plant resistance gene Rph20 to provide stable leaf rust resistance across environments. Stable resistance to barley leaf rust (BLR, caused by Puccinia hordei) was evaluated across environments in barley breeding p...

Pyrenophora teres f. teres (Ptt) is the causal agent of net form of net blotch (NFNB) – a major foliar disease of barley (Hordeum vulgare) crops worldwide. Deployment of genetic resistance in cultivars is the preferred method of control, but requires knowledge of the pathogenic variation of Ptt to be effective as spatial and temporal variation is c...

We identified Rph24 as a locus in barley (Hordeum vulgare L.) controlling adult plant resistance (APR) to leaf rust, caused by Puccinia hordei. The locus was previously reported as a quantitative trait locus in barley line ND24260-1 and named qRphND. We crossed ND24260-1 to the leaf-rust-susceptible standard Gus and determined inheritance patterns...

To respond faster to the changing climate, evolving pathogens and to feed a global population of 9–10 billion by 2050, plant breeders are exploring more efficient crop improvement strategies. In this study, we applied novel methodology for rapid trait introgression to the European two-rowed barley cultivar Scarlett. Scarlett is widely-grown in Arge...

Net blotch caused by Pyrenophora teres is major barley (Hordeum vulgare) leaf disease in Australia resulting in potential yield losses of up to 40% to the barley grains industry. Pyrenophora teres occurs as two forms; Pyrenophora teres f. teres (Ptt), showing net-like symptoms, and Pyrenophora teres f. maculata (Ptm), showing spot-like symptoms. Th...

Key message Evaluation of resistance to Pyrenophora teres f. maculata in barley breeding populations via association mapping revealed a complex genetic architecture comprising a mixture of major and minor effect genes. Abstract In the search for stable resistance to spot form of net blotch (Pyrenophora teres f. maculata, SFNB), association mappi...

A recently developed spot form of net blotch differential set of 16 barley lines was tested for reaction response to 60 Pyrenophora teres f. maculata isolates from geographically disperse barley crops of Australia. Twelve barley lines (Arimont, Barque, Chebec, CI5286, CI5791, CI9214, CII6150, Dairokkaku, Esperance Orge 289, Galleon, Keel, Skiff, To...

Supplementary material 1 The integrated map used as the reference map for QTL projection including Wenzl et al. (2006), RWA (ND19119-5/PI 642914) and ND24260/Flagship maps, including a total of 3,476 markers positions

Key message: "To find stable resistance using association mapping tools, QTL with major and minor effects on leaf rust reactions were identified in barley breeding lines by assessing seedlings and adult plants." Three hundred and sixty (360) elite barley (Hordeum vulgare L.) breeding lines from the Northern Region Barley Breeding Program in Austra...

A survey of the Australian barley powdery mildew (Blumeria graminis f. sp. hordei) population was conducted in 2010 and 2011. Three hundred and sixty-two isolates of the pathogen were collected from 18 locations across all six states of Australia. Thirty-two barley differentials were used and 11 genotypes were able to differentiate the population w...

Genomic regions influencing resistance to powdery mildew [Blumeria graminis (DC.) E.O. Speer f. sp. hordei Em. Marchal] were detected in a doubled haploid (DH) barley (Hordeum vulgare L.) population derived from a cross between the breeding line ND24260 and cultivar Flagship when evaluated across four field environments in Australia and Uruguay. Si...

Rph20 is the only reported, simply inherited gene conferring moderate to high levels of adult plant resistance (APR) to leaf rust (Puccinia hordei Otth) in barley (Hordeum vulgare L.). Key parental genotypes were examined to determine the origin of Rph20 in two-rowed barley. The Dutch cultivar 'Vada' (released in the 1950s) and parents, 'Hordeum la...

The responses of 95 barley lines and cultivars to spot form of net blotch (SFNB) caused by Pyrenophora teres f. maculata were analyzed as seedlings and adults in Australia and Canada. Cluster analyses revealed complex reaction responses. Only 2 lines (Esperance Orge 289 and TR3189) were resistant to all isolates at the seedling stage, whereas 15 li...

Barley (Hordeum vulgare L.) is a major crop in Australia and powdery mildew (Blumeria graminis f. sp. hordei) is one of its mostcommondiseases. Genes for resistance to powdery mildew were postulated for 86 Australian barley varieties and nine advanced breeding lines using 40 reference isolates of the pathogen. Fifty isolates collected in Australia...

A genetic map of barley (Hordeum vulgare L.) with 163 amplified fragment length polymorphism and 69 simple sequence repeat (SSR) markers was constructed using a population of 178 doubled haploid lines from a cross between the varieties ‘Baudin’ and ‘AC Metcalfe’. Linkage groups were assigned to barley chromosomes using published map locations of SS...

A doubled haploid (DH) barley (Hordeum vulgare L.) population of 334 lines (ND24260 × Flagship) genotyped with DArT markers was used to map genes for adult plant resistance (APR) to leaf rust (Puccinia hordei Otth) under field conditions in Australia and Uruguay. The Australian barley cultivar Flagship carries an APR gene (qRphFlag) derived from th...

Bipolaris sorokiniana (teleomorph: Cochliobolus sativus) is the fungal pathogen responsible for spot blotch in barley (Hordeum vulgare L.) and occurs worldwide in warmer, humid growing conditions. Current Australian barley varieties are largely susceptible to this disease and attempts are being made to introduce sources of resistance from North Ame...

Fourteen single nucleotide polymorphisms (SNPs) were identified at the mating type (MAT) loci of Pyrenophora teres f. teres (Ptt), which causes net form (NF) net blotch, and P. teres f. maculata (Ptm), which causes spot form (SF) net blotch of barley. MAT-specific SNP primers were developed for polymerase chain reaction (PCR) and the two forms were...

With 2 figures and 5 tables Net type net blotch (NTNB) is an important barley disease in Australia and elsewhere, with significant yield reduction. This trait is important in selection along with other traits of quality and agronomic value. Two-hundred doubled-haploid lines were generated through anther culture from a cross between ‘Pompadour’ and...

There are two recognized forms of the disease net blotch of barley: the net form caused by Pyrenophora teres f. teres (PTT) and the spot form caused by P. teres f. maculata (PTM). In this study, amplified fragment length polymorphism analysis was used to investigate the genetic diversity and population structure of 60 PTT and 64 PTM isolates collec...

Bipolaris sorokiniana (teleomorph: Cochliobolus sativus), the causal agent of common root rot (CRR) and foliar spot blotch (SB) diseases in barley and wheat, is an economically important fungal pathogen worldwide. However, the relationship between these two diseases is poorly understood. Differences within Australian B. sorokiniana populations were...

Bipolaris sorokiniana (teleomorph: Cochliobolus sativus) is the fungal pathogen responsible for spot blotch in barley (Hordeum vulgare L.) and occurs worldwide in warmer, humid growing conditions. Current Australian barley varieties are largely susceptible to this disease and attempts are being made to introduce sources of resistance from North Ame...

International comparison of virulence profiles of Pyrenophora teres f. teres (Ptt), the cause of barley net blotch, is seriously restricted by inconsistencies in differential testers used among researchers. This paper reports an attempt to develop an appropriate set of differentials to standardize characterization of Ptt populations globally. Fourt...

A genetic and phenotype comparison of Bipolaris sorokiniana isolates causing spot blotch and common root rot on barley.

Net form of net blotch (NFNB), caused by Pyrenophora teres Drechs. f. teres Smedeg., is a serious disease problem for the barley industry in Australia and other parts of the world. Three doubled haploid barley populations, Alexis/Sloop, WI2875-1/Alexis, and Arapiles/Franklin, were used to identify genes conferring adult plant resistance to NFNB...

Control of wheat rusts in north-eastern Australia has been based on resistance breeding since the early 1920s. It has been an enduring journey of discovery, disappointment, and achievement, which has culminated in a pool of knowledge and expertise upon which today's plant breeders can efficiently target durable resistance to the major rust diseases...

Malting barley (Hordeum vulgare L.) improvement involves selection for many quality traits, but the search for and deployment of resistance genes has continued to be an equally important endeavour. As an aid to phenotypic selection in breeding programs, gene mapping can serve to characterise genes known to exist in elite breeding lines. In the pres...

Pathotypes of Cochliobolus sativus have been reported overseas but variation in the Australian population has not been investigated nor have the optimum conditions for the identification of variation been established. Preliminary experiments showed that maximum separation of infection responses of seedlings to infection by C. sativus conidia was ob...

The use of fungicides to control yellow spot in wheat, caused by Pyrenophora tritici-repentis, in the northern wheat region of Australia, was examined in three field experiments. Field conditions were conducive to disease development. This was aided by spreading stubble infested with P. tritici-repentis and by regular spray irrigations, and moderat...

Quantitative trait loci (QTLs) associated with resistance to net blotch and their chromosomal,locations were determined from analyses of doubled haploid progeny of Alexis/Sloop, Arapiles/Franklin, Sloop/Halcyon, and recombinant inbred lines of Sloop-sib/Alexis. Five QTLs on chromosomes 2H, 3H, and 4H were found to be associated with seedling resist...

A doubled haploid population of 120 individuals was produced from the parents Chebec, an Australian 2-row barley of feed quality with resistance to the cereal cyst nematode, and Harrington, a 2-rowed, Canadian variety of premium malting quality. This paper describes 18 field and laboratory experiments conducted with the population and summarises th...

Two populations between the German malting variety Alexis and the Australian malting variety Sloop were constructed, mapped, phenotyped, and subjected to quantitative trait loci analysis. One population consisted of 153 F4-derived recombinant inbred lines and the other of 111 doubled haploid lines. This paper describes 18 field and laboratory exper...

Identification and deployment of disease resistance genes are key objectives of Australian barley breeding programs. Two doubled haploid (DH) populations derived from Tallon × Kaputar (TK) and VB9524 × ND11231 (VN) crosses were used to identify markers for net type net blotch (NTNB) (Pyrenophora teres f. teres). The maps included 263 and 250 marker...

Spot form of net blotch (SFNB) (Pyrenophora teres f. maculata) is an economically damaging foliar disease of barley in many of the world's cereal-growing areas. The gene Rpt4 that confers seedling resistance to SFNB has been mapped on the long arm of chromosome 7H, but no genes for adult plant resistance (APR) have been identified. A lack of field...

Net type net blotch (NTNB) is a prevalent disease in Australia, causing significant losses in barley yield and quality. Its impact can be reduced with the identification and utilisation of effective sources of resistance. Sixty-nine cultivated barley lines were screened as seedlings against 9 isolates of Pyrenophora teres f. teres from Australia, a...

A genetic linkage map of Hordeum vulgare L. 1280 cM in length, composed of 257 AFLP, RFLP, SNP, and microsatellite markers, has been constructed. The map was based on a doubled haploid population made from the cross Sloop (spring type) × Halcyon (winter type). The genetic map was used to identify qualitative major genes and quantitative trait loci...

A genetic map of barley with 224 AFLP and 39 simple sequence repeat (SSR) markers was constructed using a doubled haploid (DH) mapping population from a cross between the varieties Tallon and Kaputar. Linkage groups were assigned to individual barley chromosomes using the published map locations of the SSR markers as reference points. This genetic...

Studies on variation, occurrence and distribution of virulence in Pyrenophora teres f. teres are essential to identify effective sources of resistance for net type net blotch. Disease surveys suggested two different stains are prevalent in Western Australia and 13 in all around Australia. Sixty nine barley lines from different breeding groups in Au...

Thirty-eight Australian commercial cultivars of barley were screened as seedlings against 11 pathotypes of the leaf rust pathogen (Puccinia hordei Otth.) detected in Australia, and as adult plants in the field against the 2 predominant pathotypes (210 P+ and 200 P+) present in the eastern mainland states. Most cultivars were susceptible as seedling...

The effects of epidemics of leaf rust (Puccinia hordei Otth.) on grain size and yield of some commercial Australian barley cultivars were determined in 3 field experiments at or near Toowoomba in 1985, 1989 and 1990. Yield was reduced by 38% for the highly susceptible cultivar, Gus, in a mild to moderate epidemic in 1985; cvv. Prior, Schooner, Clip...

The effects of inoculum pressure on the development of epidemics of Puccinia graminis tritici in two barley cultivars with different levels of resistance were examined in two field experiments. Treatments were established by inoculation of foci within plots and/or the strategic use of fungicides. Additional 'rust-free' treatments were maintained to...

No complete resistance to Pyrenophora tritici-repentis has been located in more than 1400 bread wheats examined. Incomplete resistance, however, occurs at different levels in many spring and winter types and data are presented for the strongest sources of resistance detected. In particular, there is a high frequency of Brazilian spring wheats with...

The progress of epidemics of Puccinia graminis f. sp. tritici strain 343-Anz-1,2,3,5,6 was examined in field plots of the Australian barley cultivars Clipper, Corvette, Galleon, Grimmett, Prior and Schooner. The barley Purple Nudum, reported to possess seedling resistance to Puccinia graminis f. sp. tritici, and the susceptible wheat Oxley were als...

Severe epidemics of yellow spot (Pyrenophora tritici-repentis) reduced grain yield by c. 60% in the highly susceptible wheat cv. Banks in two experiments. About two-thirds of the yield loss was associated with reduced grain size. Milder epidemics developed in cultivars with incomplete resistance and resulted in substantially smaller effects on grai...

Effects of early and full season epidemics by stripe rust (Puccinia striiformis f. sp. Tritici) were examined in 12 wheat cultivars with different levels of adult plant resistance (APR). The APR in Cook, Bass, Banks, Kite, and Suneca was generally effective in preventing detectable yield losses due to stripe rust infection. Cultivars with lower lev...

The response of Australian wheats to yellow spot caused by Pyrenophora tritici-repentis has been examined under controlled conditions with a juvenile-plant screening system. About three-quarters of contemporary Australian wheats are highly susceptible to the disease and very few cultivars possess useful levels of resistance. Also, the majority of A...

Effects of yellow spot (Pyrenophoua tuitici-repentis) on two cultivars (Banks and Olympic) of wheat have been examined in a field experiment where distinctly different epidemics were produced in various treatments. Severe yellow spot before jointing reduced production of both tillers and dry matter, and substantially lowered leaf area index at join...

Losses in wheat yield associated with yellow spot (Pyrenophora tritici-repentis) have been examined in a field experiment where development of crop and disease were promoted with sprinkler irrigation. Different amounts of infected wheat stubble were applied to initiate epidemics in four treatments, while fungicide sprays were used to reduce the sev...

The effect of yellow spot (Pyrenophora tritici-repentis) on wheat yield has been examined with a single-tiller technique. The disease was assessed on c. 1000 tagged main stems in each of five wheat crops. Grain yield, its components, and harvest index were measured on each tiller. In most cases these response variables were significantly correlated...

Aspects of the epidemiology of yellow spot of wheat, caused by Pyrenophovu tritici-repentis, have been examined in southern Queensland. Ascospores of the fungus were detected In the air above wheat stubble between March and October, but numbers at any one time were small. Small numbers of conidia trapped between late February and May apparently ori...

Explanations were sought for the increased severity of yellow spot of wheat (Pyrenophora tritici-repentis) in the north-eastern wheat growing areas of Australia. A close association between the severity of yellow spot and stubble management practices was found in a field experiment. There was less disease in plots where stubble had been burned (0.8...

The control of wheat leaf rust (Puccinia recondita tritici) by seed or foliar applications of 4-n-butyl-l,2,4-triazole (RH-124) has been examined in field experiments over three years at Gatton, Queensland. Single foliar sprays of RH-124 at rates as low as 100 g a.i, ha-1 have given excellent control of leaf rust. One such spray resulted in a yield...

Reliable barley production in north-eastern Australia requires resistance to six foliar diseases. Leaf rust, stem rust, net blotch, spot form of net blotch, spot blotch and powdery mildew can be endemic under favourable conditions. Resistance to multiple diseases is an objective of the Northern Barley Improvement Program and is being addressed by h...

Pedigree-based whole genome (PBWG) mapping offers significant potential to increase the genetic gains made in plant breeding programs through the development of systems for marker assisted selection. Effective use of a PBWG marker approach requires relevant pedigree and phenotypic data, low-cost, high throughput genotyping and a data management and...

The fungus B. sorokiniana (Sacc. in Sorok.) causes spot blotch of barley which is a significant foliar disease of barley in northern New South Wales and Queensland. In the Northern barley region, spot blotch is more common in central Queensland and the sub-coastal areas and can also become widespread in inland areas when environmental conditions ar...

A dihaploid mapping population comprising 65 lines was developed between barley parent varieties Tallon and Kaputar and used to construct a genetic linkage map. This map, comprising 195 amplified fragment length polymorphism and 38 simple sequence repeat markers, was used to identify markers linked to the net form of net blotch (Pyrenophora teres f...