SOURCES OF RESISTANCE IN BARLEY TO PYRENOPHORA TERES

The distribution in western Canada of three biotypes of Pyrenophora teres, the cause of net blotch of barley, was determined. Two of these produced typical net blotch symptoms but differed in virulence and were found throughout the prairies in 1974. The third, which produces spot-like symptoms, was found only in Manitoba and comprised half the total isolates. The incidence of net blotch was higher in fields of two-rowed than in six-rowed barley. Resistance to the three biotypes of P. teres was found in several barley lines when symptom expression and rate of conidial development on infected host tissue were compared. CI 9214 was superior to CI 5791, the resistance source used in some barley breeding programs.

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Epidemiology and control of spot form of net blotch (Pyrenophora teres f. maculata) of barley: a review

Crop and Pasture Science ◽

10.1071/cp08173 ◽

2009 ◽

Vol 60 (4) ◽

pp. 303 ◽

Cited By ~ 48

Author(s):

Mark S. McLean ◽

Barbara J. Howlett ◽

Grant J. Hollaway

Keyword(s):

Cost Effective ◽

Pyrenophora Teres ◽

Net Blotch ◽

Stubble Retention ◽

Resistant Varieties ◽

Cost Effective Method ◽

Barley Germplasm ◽

Grain Yield And Quality ◽

The 1960S ◽

And Control

Spot form of net blotch (SFNB), caused by the fungus Pyrenophora teres f. maculata, was first described in Denmark in the 1960s and is now a prevalent foliar disease of barley in many countries. This disease should be controlled as a separate disease-causing organism from the net form of net blotch (NFNB), which is caused by P. teres f. teres. The increase in prevalence of SFNB is primarily due to stubble retention and cultivation of susceptible varieties, which have resulted in increased inoculum. Infected barley stubble is the primary inoculum source for SFNB, producing both asexual spores (conidia) and sexual spores (ascospores) from pseudothecia. Spot form of net blotch causes significant losses in grain yield and quality in situations where inoculum is present, susceptible varieties are cultivated, and where the climate is cool and moist. Cultivation of resistant varieties is the most cost-effective method for control of SFNB and more than 12 different resistance sources have been identified in barley germplasm and wild barley relatives. The resistance loci of 11 of these have been mapped. Control of SFNB can also be achieved with application of foliar fungicides, crop rotation, and stubble destruction.

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Current Virulence of Pyrenophora teres on Barley in Western Australia

Plant Disease ◽

10.1094/pdis.2001.85.9.960 ◽

2001 ◽

Vol 85 (9) ◽

pp. 960-966 ◽

Cited By ~ 46

Author(s):

Sanjiv Gupta ◽

Robert Loughman

Keyword(s):

Western Australia ◽

Error Variance ◽

Geographic Area ◽

Australian Isolate ◽

Pyrenophora Teres ◽

Sources Of Resistance ◽

Pathogenic Variation ◽

Resistant Varieties ◽

Significant Line ◽

Spot Type

Studies on variation, occurrence, and distribution of virulence in Pyrenophora teres are helpful to identify effective sources of resistance that can be used for barley breeding in Western Australia. Seventy-nine isolates of Pyrenophora teres were collected from different barley fields of Western Australia in 1995-96. Seventy-four induced net type symptoms (P. teres f. teres) and five induced spot type symptoms (P. teres f. maculata). Net type isolate responses on 47 barley lines were similar to the range of responses induced by nine historical isolates collected in the region between 1975 and 1985. These net type isolates were classified into two distinct groups based on virulence to the cultivar Beecher. Isolates were further classified into eight groups based on minor pathogenic variation among the population. The virulence phenotype present in an eastern Australian isolate was not observed in any isolates collected from Western Australia. An analysis of variance on a subset of 12 net type isolates indicated a significant line × isolate interaction (P < 0.001), with the interaction term variance component four times larger than the error variance. Based on these studies, the virulence among net type isolates has remained stable in Western Australia for the last 19 years. Spot type isolates were collected from a wider geographic area than previously reported and varied in virulence based on response to barley line Herta. Variation in spot-type isolates is reported for the first time from the region. The results from this study are being used in the development of resistant varieties.

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Erratum to: Epidemiology and control of spot form of net blotch (Pyrenophora teres f. maculata) of barley: a review

Crop and Pasture Science ◽

10.1071/cp08173_er ◽

2009 ◽

Vol 60 (5) ◽

pp. 499 ◽

Cited By ~ 7

Author(s):

Mark S. McLean ◽

Barbara J. Howlett ◽

Grant J. Hollaway

Keyword(s):

Cost Effective ◽

Pyrenophora Teres ◽

Net Blotch ◽

Stubble Retention ◽

Resistant Varieties ◽

Cost Effective Method ◽

Barley Germplasm ◽

Grain Yield And Quality ◽

The 1960S ◽

And Control

Spot form of net blotch (SFNB), caused by the fungus Pyrenophora teres f. maculata, was first described in Denmark in the 1960s and is now a prevalent foliar disease of barley in many countries. This disease should be controlled as a separate disease-causing organism from the net form of net blotch (NFNB), which is caused by P. teres f. teres. The increase in prevalence of SFNB is primarily due to stubble retention and cultivation of susceptible varieties, which have resulted in increased inoculum. Infected barley stubble is the primary inoculum source for SFNB, producing both asexual spores (conidia) and sexual spores (ascospores) from pseudothecia. Spot form of net blotch causes significant losses in grain yield and quality in situations where inoculum is present, susceptible varieties are cultivated, and where the climate is cool and moist. Cultivation of resistant varieties is the most cost-effective method for control of SFNB and more than 12 different resistance sources have been identified in barley germplasm and wild barley relatives. The resistance loci of 11 of these have been mapped. Control of SFNB can also be achieved with application of foliar fungicides, crop rotation, and stubble destruction.

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Resistance in cultivated barleys to Pyrenophora teres f. teres and prospects of its utilisation in marker identification and breeding

Australian Journal of Agricultural Research ◽

10.1071/ar03022 ◽

2003 ◽

Vol 54 (12) ◽

pp. 1379 ◽

Cited By ~ 11

Author(s):

S. Gupta ◽

R. Loughman ◽

G. J. Platz ◽

R. C. M. Lance

Keyword(s):

Resistance Breeding ◽

Pyrenophora Teres ◽

Net Blotch ◽

Sources Of Resistance ◽

Yield And Quality ◽

Prevalent Disease ◽

Overall Resistance ◽

Mapping Populations ◽

Marker Identification ◽

Virulence Diversity

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, and in the field in Western Australia. Resistance expressed in seedlings was frequently expressed in adult plants in the field, indicating that these sources are potentially useful for resistance breeding. Of these lines, 24 with the best overall resistance were identified, which could be used against virulence diversity present in P. teres f. teres in Australia.As a prelude to the evaluation of established mapping populations in the Australian Barley Molecular Marker Program, 42 parental lines were screened against a range of Australian isolates of P. teres f. teres. Variation in net blotch responses was observed among parents of the mapping populations. Ten principal mapping populations appear to provide opportunities to map resistances and identify molecular markers linked to NTNB resistance genes effective against Australian pathotypes.

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Identification of Pyrenophora teres f. maculata, Causal Agent of Spot Type Net Blotch of Barley in North Dakota

Plant Disease ◽

10.1094/pdis-94-4-0480a ◽

2010 ◽

Vol 94 (4) ◽

pp. 480-480 ◽

Cited By ~ 15

Author(s):

Z. H. Liu ◽

T. L. Friesen

Keyword(s):

North Dakota ◽

Leaf Tissue ◽

Causal Agent ◽

Tan Spot ◽

Pathogenicity Test ◽

Pyrenophora Teres ◽

Net Blotch ◽

Hordeum Vulgare L ◽

Single Spore ◽

Spot Type

Net blotch of barley (Hordeum vulgare L.) caused by the fungus Pyrenophora teres (anamorph Drechslera teres) is found in two forms, net form net blotch (NFNB) and spot form net blotch (SFNB). When inoculated on susceptible varieties, P. teres f. teres produces lesions with a characteristic net-like pattern surrounded by necrosis or chlorosis (NFNB), whereas P. teres f. maculata produces lesions consisting of spots surrounded by necrosis or chlorosis (SFNB). Recently, epidemics of SFNB have occurred throughout the world (4). Currently, net blotch is a significant foliar disease of barley in the North Dakota-Northwestern Minnesota agricultural region, a leading barley-production area. Diseased barley leaf tissue was collected annually from 2004 to 2008 in Fargo and Langdon, ND. Diseased leaves were incubated to promote sporulation. Ten single-spore isolates of P. teres collected from each location each year were tested for virulence by inoculation on 20 commonly used barley net blotch differential lines. Among the 100 isolates collected, one isolate collected in Fargo in 2006 (FGOH06Pt-8) and one isolate collected in Langdon in 2008 (LDNH08Pt-4) were identified as P. teres f. maculata due to their induction of spot-type lesions across the differential set. Conidial morphology of the two isolates was similar to P. teres f. teres isolates. A pathogenicity test of all isolates was performed on regional barley cvs. Tradition, Robust, and Lacey as well as barley lines Rika and Kombar (1) as previously described (3). The net form isolate 0-1 and spot form isolate DEN2.6 (obtained from B. Steffenson, University of Minnesota) were used as controls. The P. teres f. teres isolate 0-1 produced typical net type symptoms on all barley lines except the resistant line Rika, in which only small, dark spots were observed. DEN2.6 produced pin-point spot-like lesions with an extensive yellow halo on Robust, Lacey, Rika, and Kombar, but without chlorosis on Tradition. The two newly identified isolates induced elliptical spot-type lesions measuring 3 × 6 mm, larger than those produced by P. teres f. maculata isolate DEN 2.6, suggesting a higher level of virulence. We constructed a neighbor-joining phylogenetic tree using ClustalW2 ( http://www.ebi.ac.uk/ ) based on sequence identity of the internal transcribed spacer (ITS) region from 0-1 (GenBank No. GU014819), DEN2.6 (GenBank No. GU014820), FGOH06Pt-8 (GenBank No. GU014821), and LDNH08Pt-4 (GenBank No. GU014822) as well as P. teres f. maculata, P. teres f. teres, and P. tritici-repentis (causal agent of tan spot of wheat) accessions obtained from GenBank (2). All P. teres isolates clustered together and were clearly separated from the P. tritici-repentis cluster. Isolates FGOH06Pt-8 and LDNH08Pt-4 had identical ITS sequences and differed from DEN2.6 by only a single nucleotide. To our knowledge, this is the first report of P. teres f. maculata in North Dakota. Resistance to SFNB should now be considered in local barley breeding programs and cultivar releases. Reference: (1) M. Abu Qamar. Theor. Appl. Genet. 117:1261, 2008. (2) R. M. Andrie et al. Fungal Genet. Biol. 45:363, 2008. (3) Z. Lai et al. Fungal Genet. Biol. 44:323, 2007. (4) M. S. McLean et al. Crop Pasture Sci. 60:303, 2009.

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First Report of Spot Form Net Blotch Caused by Pyrenophora teres f. maculata on Barley in the Mon-Dak Area of the United States

Plant Disease ◽

10.1094/pdis-07-12-0657-pdn ◽

2013 ◽

Vol 97 (1) ◽

pp. 143-143 ◽

Cited By ~ 3

Author(s):

R. T. Lartey ◽

T. C. Caesar-TonThat ◽

A. J. Caesar ◽

U. M. Sainju ◽

R. G. Evans

Keyword(s):

North Dakota ◽

Its Region ◽

The United States ◽

Northern Great Plains ◽

Pathogenicity Test ◽

Pyrenophora Teres ◽

Net Blotch ◽

Morphological Examination ◽

First Report ◽

Barley Cultivars

Pyrenophora teres Drechs. causes net blotch of barley, a common foliar disease in cultivation zones around the world. The disease occurs in two forms, namely a net form net blotch (NFNB) caused by P. teres f. teres and a spot form net blotch (SFNB) caused by P. teres f. maculata. As in other parts of the northern Great Plains, in the Mon-Dak area (western North Dakota and eastern Montana), NFNB is prevalent. SFNB was first reported in western Montana in 1983 (1) and more recently in eastern North Dakota in 2010 (3) but not in the Mon-Dak area. In the summer of 2011, unusual spot lesions that were surrounded by necrosis or chlorosis were observed on different barley cultivars in fields at Williston, ND, Nesson Valley, ND, and Sidney, MT areas. Diseased leaves from various barley cvs. from the three locations were transferred to water agar and incubated at room temperature for 24 h to induce sporulation. Morphological examination of conidia (45 to 169 × 15 to 21 μm) did not show significant differences from a known isolate of P. teres f. teres 0-1 (provided by Tim Friesen, ARS, Fargo, ND). For pathogenicity testing, six 14-day-old plants of barley cv. Tradition were sprayed until runoff with a 2,000 spore/ml suspension of two isolates from each location and the control P. teres f. maculata isolate DEN2.6 (provided by Tim Friesen). Plants were incubated first in a lighted humidity chamber for 24 h and then in a greenhouse for 7 days at 21°C. Regardless of inoculum source, spot lesions surrounded by necrosis or chlorosis, typical of SFNB, appeared on the inoculated leaves within 7 days. Fungi isolated from symptomatic leaves were identified as P. teres and the morphology of the conidia was undistinguishable from those of P. teres f. teres. All control plants which were sprayed with sterile distilled water were symptomless. The pathogenicity test was repeated. Rapid PCR detection and amplicon sequencing (2) of the internal transcribed spacer (ITS) region of ribosomal genes was performed on field and pathogenicity test leaf lesion samples to confirm the presence of P. teres f. maculata. DNA templates were prepared using the Extract-N-Amp Plant PCR Kits (Sigma Chemical Co., St. Louis, MO) and subjected to PCR using ITS1 and ITS4 primers. Amplicons were then purified and sequenced. The 585-bp nucleotide sequences of P. teres f. maculata from Mon-Dak area were submitted to GenBank under accession nos. PtmNES1 (JX187587), PtmSDY1 (JX187588), PtmSDY2 (JX187589), and PtmWIL1 (JX187590). The sequences from the four locations shared 100% similarity and also with P. teres f. maculata (EF452471) from GenBank while showing 10 nucleotide differences (99% similarity) with P. teres f. teres (EF452472).The results represent first report of SFNB in the Mon-Dak. Barley is one of the most important crops in the area. Resistance of the NFNB and SFNB of barley are controlled by different genes (4). Based on this report, SFNB therefore have to be considered in selection of barley cultivars for cultivation in the area. References: (1) H. E Bockelman et al. Plant Dis. 67:696, 1983. (2) R. T. Lartey et al. J. Sugar Beet Res. 40:1, 2003. (3) Z. H. Liu and T. L. Friesen. Plant Dis. 94:480, 2010. (4) O. M. Manninen et al. Genome. 46:1564, 2006.

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Virulence Profile and Genetic Structure of a North Dakota Population of Pyrenophora teres f. teres, the Causal Agent of Net Form Net Blotch of Barley

Phytopathology ◽

10.1094/phyto-09-11-0243 ◽

2012 ◽

Vol 102 (5) ◽

pp. 539-546 ◽

Cited By ~ 26

Author(s):

Z. H. Liu ◽

S. Zhong ◽

A. K. Stasko ◽

M. C. Edwards ◽

T. L. Friesen

Keyword(s):

North Dakota ◽

Gene Diversity ◽

Random Mating ◽

Common Source ◽

Pyrenophora Teres ◽

Net Blotch ◽

Seedling Resistance ◽

Wide Range ◽

Significant Difference ◽

Net Form Net Blotch

A Pyrenophora teres f. teres population in North Dakota was analyzed for virulence variation and genetic diversity using 75 monospore isolates that were collected across a 4-year period (2004 to 2007) from two North Dakota State University agricultural experiment stations at Fargo and Langdon. Pathogenicity tests by inoculation onto 22 barley differential lines at seedling stage revealed 49 pathotypes, indicating a wide range of pathogenic diversity. Two-way analysis of variance of disease ratings revealed a significant difference in the virulence among isolates and in the resistance among barley lines, as well as in the interactions between the two. ‘CI5791’, ‘Algerian’, and ‘Heartland’ were three barley lines showing a high level of seedling resistance to all North Dakota isolates tested; however, many previously reported resistance genes have been overcome. Forty multilocus genotypes were identified from this set of isolates by genotyping at 13 simple-sequence repeat loci. High percentages of clonal cultures were detected in the samplings from 2005 and 2007 in Fargo and 2005 in Langdon. Using a clone-corrected sample set, the mean gene diversity (h) was estimated to be 0.58, approximately the same for both locations. The calculated Wright's FST value is small (0.11) but was significantly >0, indicating a significant differentiation between the Fargo and Langdon populations. In the gametic disequilibrium test, only 3 of 78 possible pairwise comparisons over all isolates showed significant (P < 0.05) nonrandom association, suggesting a random mating mode. Our results suggest that the populations from the two locations are derived from a common source and undergo frequent recombination. This research provides important information for barley breeders regarding development and deployment of cultivars with resistance to net form net blotch in this region.

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Genome wide association mapping of Pyrenophora teres f. maculata and Pyrenophora teres f. teres resistance loci utilizing natural Turkish wild and landrace barley populations

10.1101/2021.06.07.447398 ◽

2021 ◽

Author(s):

Shaun James Clare ◽

Arzu Çelik Oğuz ◽

Karl Effertz ◽

Roshan Sharma Poudel ◽

Deven See ◽

...

Keyword(s):

Fungal Pathogens ◽

Genome Wide Association Study ◽

Association Studies ◽

Hordeum Spontaneum ◽

Genome Wide Association ◽

Genome Wide Association Studies ◽

Pyrenophora Teres ◽

Net Blotch ◽

Sources Of Resistance ◽

Genome Wide

Unimproved landraces and wild relatives of crops are sources of genetic diversity that were lost post domestication in modern breeding programs. To tap into this rich resource, genome wide association studies in large plant genomes have enabled the rapid genetic characterization of desired traits from natural landrace and wild populations. Wild barley (Hordeum spontaneum), the progenitor of domesticated barley (H. vulgare), is dispersed across Asia and North Africa, and has co-evolved with the ascomycetous fungal pathogens Pyrenophora teres f. teres and P. teres f. maculata, the casual agents of the diseases net form of net blotch and spot form of net blotch, respectively. Thus, these wild and local adapted barley landraces from the region of origin of both the host and pathogen represent a diverse gene pool to identify new sources of resistance, due to millions of years of co-evolution. The barley - P. teres pathosystem is governed by complex genetic interactions with dominant, recessive, and incomplete resistances and susceptibilities, with many isolate-specific interactions. Here we provide the first genome wide association study of wild and landrace barley from the Fertile Crescent for resistance to both forms of P. teres. A total of 14 loci, four against P. teres f. maculata and ten against Pyrenophora teres f. teres, were identified in both wild and landrace populations, showing that both are genetic reservoirs for novel sources of resistance. We also highlight the importance of using multiple algorithms to both identify and validate additional loci.

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First Report of Spot Type of Barley Net Blotch Caused by Pyrenophora teres f. sp. maculata in Uruguay

Plant Disease ◽

10.1094/pdis.2004.88.10.1162c ◽

2004 ◽

Vol 88 (10) ◽

pp. 1162-1162

Author(s):

S. A. Pereyra ◽

S. E. Germán

Keyword(s):

North Dakota ◽

Tween 20 ◽

Pyrenophora Teres ◽

Sterile Water ◽

Net Blotch ◽

First Report ◽

Production Region ◽

Resistant Infection ◽

Infection Types ◽

Spot Type

In September 2003, leaves exhibiting spot-type lesions similar to those produced by Cochliobolus sativus Drechs. ex Dastur were widely observed in six commercial barley crops of cvs. Norteña Daymán, Norteña Carumbé, and MUSA 936 in Soriano and Río Negro provinces, the main barley production region in western Uruguay. Spot lesions were tan to dark brown, circular to elliptical, and 3 to 10 mm in diameter. Larger lesions were surrounded by a chlorotic margin of varying width. Affected leaf pieces (10 to 15) from each field were placed in a moist chamber for 2 days to promote sporulation. A fungus identified morphologically as Pyrenophora teres (Died.) Drechs. (1) was consistently isolated from infected leaves. However, symptoms did not correspond to the net-type lesions of net blotch commonly produced by P. teres f. sp. teres in Uruguay. Three monoconidial cultures were obtained by transferring single conidia to potato dextrose agar and then to 10% V8 juice agar and incubated at 20 to 22°C with a 12-h photoperiod for 10 days. Adding sterile water to each plate and gently rubbing the surface with a microscope slide prepared inoculum for pathogenicity tests. Conidia concentration was adjusted to 1 × 104 conidia per ml. Sixty-eight barley genotypes from Uruguay, ICARDA/CIMMYT, and North Dakota were grown in the greenhouse for 2 weeks at 20 to 22°C with a 14-h photoperiod. For each monoconidial isolate, three seedlings of each genotype were inoculated at the three-leaf stage 15 to 16 days after seeding with 0.4 ml of the inoculum suspension with an airbrush inoculator. A drop of Tween 20 was added per 40 ml of inoculum suspension. One set of each genotype was inoculated with sterile water as a control. Seedlings were placed in a dew chamber at 20°C and 100% relative humidity in the dark for 24 h and then returned to prior conditions. The first lesions developed after 7 to 9 days. Leaves two and three of the plants were visually rated for disease (3) 13 days after inoculation. Control plants were disease free. The most susceptible reactions were observed on cvs. Norteña Daymán, MUSA 936, and line CLE 230 (Uruguay). Symptoms were similar in shape and size to those observed in the fields. The most resistant infection types were observed on several Uruguayan and North Dakota advanced lines. The fungus was consistently reisolated from inoculated plants. On the basis of morphology and symptoms produced, the pathogen was identified (2) as P. teres. f. sp. maculata Smedeg. To our knowledge, this is the first report of this fungus causing spot-like symptoms of net blotch in Uruguay. References: (1) M. B. Ellis. Dematiaceous hyphomycetes, CABI, Oxon, UK, 1971. (2) V. Smedergaard-Petersen. Pages 124–144 in: R. Vet. Agr. Univ. Yearbook, Copenhagen, 1971. (3) A. Tekauz. Can. J. Plant Pathol.7:181, 1985.

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