Races, disease symptoms and genetic variability in Pyrenophora tritici-repentis isolates from Oklahoma that cause tan spot of winter wheat

AbstractIn recent years, tan spot of wheat caused by the fungus Pyrenophora tritici-repentis has become more prevalent in Oklahoma. Experiments were conducted to investigate the race structure, disease symptoms and genetic variability in P. tritici-repentis isolates collected from winter wheat over three decades. Race determination was conducted for 16 isolates based on expression of necrosis and/or chlorosis produced on wheat differentials. Variability in disease symptoms expressed by 12 isolates was determined on 13 hard red winter wheat cultivars grown in Oklahoma. In addition, genetic variability among 17 isolates was determined using amplified fragment length polymorphism-polymerase chain reaction (AFLP-PCR). All isolates except one (El Reno) were classified as race 1. Isolates varied widely in producing necrosis and/or chlorosis symptoms on wheat cultivars, but necrosis with a chlorotic halo was predominant (56.4%). AFLP-PCR analysis using 13 primer pairs produced a total of 494 alleles of which 285 were polymorphic. The overall genetic diversity among the isolates was 25.2%. Genetic relationships based on cluster analysis and principal component analysis showed only minor differences between isolates, and isolates did not form tight clusters or groups. The isolates of P. tritici-repentis were predominantly race 1; however, they produced a range of tan spot symptoms on wheat cultivars. The lack of distinct genetic grouping by the AFLP marker study indicates that the isolates used in this study likely originated from a single lineage.

Download Full-text

Genetic Control of Resistance to Tan Necrosis Induced by Pyrenophora tritici-repentis, Races 1 and 2, in Spring and Winter Wheat Genotypes

Phytopathology ◽

10.1094/phyto-95-0172 ◽

2005 ◽

Vol 95 (2) ◽

pp. 172-177 ◽

Cited By ~ 30

Author(s):

P. K. Singh ◽

G. R. Hughes

Keyword(s):

Winter Wheat ◽

Genetic Control ◽

Recessive Gene ◽

Tan Spot ◽

Wheat Genotypes ◽

Resistant Cultivars ◽

Pyrenophora Tritici Repentis ◽

Lesion Type ◽

Race 1 ◽

Race 2

The symptoms of tan spot of wheat, caused by Pyrenophora triticirepentis, include a tan necrosis component and an extensive chlorosis component. Since tan spot has become the major component of the leafspotting disease complex of wheat in western Canada, the need for resistant cultivars has increased. This study was conducted to determine whether the resistance to tan spot found in a diverse set of spring and winter wheat genotypes was due to resistance genes not previously reported. The genetic control of resistance to necrosis induced by P. triticirepentis race 1 and race 2 was determined, under controlled environmental conditions, for spring wheat genotypes Erik and 86ISMN 2137 and winter wheat genotypes Hadden, Red Chief, and 6B-365. Plants were inoculated at the two-leaf stage and disease reaction was assessed based on lesion type. Tests of the F1 and F2 generations, and of F2:3 and F2:8 families, indicated that one recessive gene controlled resistance to the necrosis component of tan spot caused by both race 1 and race 2 in each cross studied. Lack of segregation in crosses between the resistant cultivars indicated that the resistance gene was the same in all of the cultivars.

Download Full-text

Identification and Characterization of Novel Isolates of Pyrenophora tritici-repentis from Arkansas

Plant Disease ◽

10.1094/pdis-94-2-0229 ◽

2010 ◽

Vol 94 (2) ◽

pp. 229-235 ◽

Cited By ~ 31

Author(s):

Shaukat Ali ◽

Suraj Gurung ◽

Tika B. Adhikari

Keyword(s):

The United States ◽

Tan Spot ◽

Wheat Cultivars ◽

Pyrenophora Tritici Repentis ◽

Winter Wheat Cultivars ◽

Race 1 ◽

Preliminary Study ◽

Polymerase Chain ◽

Identification And Characterization

Tan spot, caused by Pyrenophora tritici-repentis, is an important foliar disease of wheat (Triticum aestivum) worldwide. In a preliminary study, P. tritici-repentis isolates from Arkansas were shown to vary in virulence relative to isolates from other regions of the United States. Therefore, the aim of the current study was to characterize both pathogenic and molecular variations in P. tritici-repentis isolates from Arkansas. The virulence of 93 isolates of P. tritici-repentis was evaluated by inoculating five differential wheat cultivars/lines. Based on virulence phenotypes, 63 isolates were classified as race 1, and 30 isolates were assigned to race 3. A subset of 42 isolates was selected for molecular characterization with the presence or absence of the ToxA and ToxB genes. The results showed that 36 isolates out of 42 tested by polymerase chain reaction (PCR) and Southern analysis lacked the ToxA and ToxB genes. Six isolates harboring the ToxA and ToxB genes induced necrosis and chlorosis on Glenlea and 6B365, respectively. Thirteen ToxA gene-deficient isolates also caused necrosis and chlorosis on Glenlea and 6B365, respectively; however, they did not fit current race classification. In contrast, the remaining 23 ToxA gene-deficient isolates did not cause necrosis, but induced chlorosis on 6B365, showing a disease profile for race 3. When the virulence of AR LonB2 (an isolate with unclassified race) was compared with known races 1, 3, and 5 of P. tritici-repentis on 20 winter wheat cultivars from Arkansas, the virulence phenotypes differed substantially. Taken together, the ToxA and ToxB gene-deficient isolates of P. tritici-repentis that induce necrosis and/or chlorosis may produce a novel toxin(s) on wheat.

Download Full-text

Characterization of Pyrenophora tritici-repentis in Tunisia and Comparison with a Global Pathogen Population

Plant Disease ◽

10.1094/pdis-04-21-0763-re ◽

2021 ◽

Author(s):

Marwa Laribi ◽

Alireza Akhavan ◽

Sarrah M'Barek ◽

Amor Yahyaoui ◽

Stephen Ernest Strelkov ◽

...

Keyword(s):

Genetic Diversity ◽

Geographic Origin ◽

Tan Spot ◽

Pcr Analysis ◽

Group Method ◽

Region Of Origin ◽

Pyrenophora Tritici Repentis ◽

Pair Group ◽

Necrotrophic Effector

Pyrenophora tritici-repentis (Ptr) causes tan spot, an important foliar disease of wheat. A collection of Ptr isolates from Tunisia, located in one of the main secondary centers of diversification of durum wheat, was tested for phenotypic race classification based on virulence on a host differential set, and for the presence of the necrotrophic effector (NE) genes ToxA, ToxB , and toxb by PCR analysis. While races 2, 4, 5, 6, 7, and 8 were identified according to their virulence phenotypes, PCR testing indicated the presence of ‘atypical’ isolates that induced necrosis on the wheat differential ‘Glenlea’, but lacked the expected ToxA gene, suggesting the involvement of other NEs in the Ptr/wheat interaction. Genetic diversity and the Ptr population structure were explored further by examining 59 Tunisian isolates and 35 isolates from Algeria, Azerbaijan, Canada, Iran, and Syria using 24 simple sequence repeat markers. Average genetic diversity, overall gene flow and percentage polymorphic loci were estimated as 0.58, 2.09 and 87%, respectively. Analysis of molecular variance showed that 81% of the genetic variance occurred within populations and 19% between populations. Cluster analysis by the unweighted pair group method indicated that ToxB- isolates grouped together and were distantly related to ToxB+ isolates. Based on Nei’s analysis, the global collection clustered into two distinct groups according to their region of origin. The results suggest that both geographic origin and the host-specificity imposed by different NEs can lead to differentiation among Ptr populations.

Download Full-text

A Novel Source of Resistance in Wheat to Pyrenophora tritici-repentis Race 1

Plant Disease ◽

10.1094/pdis-92-1-0091 ◽

2008 ◽

Vol 92 (1) ◽

pp. 91-95 ◽

Cited By ~ 22

Author(s):

Sukhwinder Singh ◽

William W. Bockus ◽

Indu Sharma ◽

Robert L. Bowden

Keyword(s):

Great Plains ◽

Recombinant Inbred Lines ◽

The United States ◽

Interval Mapping ◽

Tan Spot ◽

Sources Of Resistance ◽

Pyrenophora Tritici Repentis ◽

Ptr Toxa ◽

Chromosome 5B ◽

Race 1

Tan spot, caused by the fungus Pyrenophora tritici-repentis, causes serious yield losses in wheat (Triticum aestivum) and many other grasses. Race 1 of the fungus, which produces the necrosis toxin Ptr ToxA and the chlorosis toxin Ptr ToxC, is the most prevalent race in the Great Plains of the United States. Wheat genotypes with useful levels of resistance to race 1 have been deployed, but this resistance reduces damage by only 50 to 75%. Therefore, new sources of resistance to P. tritici-repentis are needed. Recombinant inbred lines developed from a cross between the Indian spring wheat cvs. WH542 (resistant) and HD29 (moderately susceptible) were evaluated for reaction to race 1 of the fungus. Composite interval mapping revealed quantitative trait loci (QTL) on the short arm of chromosome 3A explaining 23% of the phenotypic variation, and the long arm of chromosome 5B explaining 27% of the variation. Both resistance alleles were contributed by the WH542 parent. The QTL on 5BL is probably tsn1, which was described previously. The 3AS QTL (QTs.ksu-3AS) on 3AS is a novel QTL for resistance to P. tritici-repentis race 1. The QTL region is located in the most distal bin of chromosome 3AS in a 2.2-centimorgan marker interval. Flanking markers Xbarc45 and Xbarc86 are suitable for marker-assisted selection for tan spot resistance.

Download Full-text

Principal component analysis for functional data on grain yield of winter wheat cultivars

Biometrical Letters ◽

10.2478/bile-2013-0019 ◽

2013 ◽

Vol 50 (2) ◽

pp. 81-94 ◽

Cited By ~ 2

Author(s):

Mirosław Krzyśko ◽

Adriana Derejko ◽

Tomasz Górecki ◽

Edward Gacek

Keyword(s):

Winter Wheat ◽

Grain Yield ◽

Adaptive Response ◽

Management Practices ◽

Crop Yields ◽

Principal Component ◽

Block Designs ◽

Wheat Cultivars ◽

Winter Wheat Cultivars ◽

Testing Environments

Summary The aim of this paper is to present a statistical methodology to assess patterns of cultivars' adaptive response to agricultural environments (agroecosystems) on the basis of complete Genotype x Crop Management x Location x Year (GxMxLxY) data obtained from 3-year multi-location twofactor trials conducted within the framework of the Polish post-registration trials (PDOiR), with an illustration of the application and usefulness of this methodology in analyzing winter wheat grain yield. Producing specific varieties for each subregion of a target region, from widely adapted varieties, may exploit positive genotype x location (GL) interactions to increase crop yields. Experiments designed to examine combinations of environment (E), management practices (M) and cultivars (G) also provide evidence of the relative importance of each of these factors for yield improvement. The evidence shows that variation due to E far outweighs the variation of grain yield that can be attributed to M or G, or the interactions between these factors, and between these factors and E (Anderson, 2010). This statistical method involves the use of functional PCA and cluster analysis. A total of 24 cultivars were evaluated over 3 years in 20 environments using randomized incomplete split-block designs with two replications per trial. The methodology proved an efficient tool for the reliable classification of 24 winter wheat cultivars, distinguishing cultivar groups that exhibited homogeneous adaptive response to environments. It enables the identification of cultivars displaying wide or specific adaptation. The remaining cultivars were locally adapted to some testing environments, or some of them were not relatively adapted to the environments because they always yielded substantially below the environmental means. Performing earlier specific selection, or adopting distinct genetic bases for each agro-ecosystem, may further increase the advantage of specific breeding.

Download Full-text

Assessing genetic variability in winter wheat cultivars using microsatellite markers

Journal of Biotechnology ◽

10.1016/j.jbiotec.2012.07.145 ◽

2012 ◽

Vol 161 ◽

pp. 45

Author(s):

Funda Senturk-Akfirat ◽

Ahu Altinkut Uncuoglu

Keyword(s):

Genetic Variability ◽

Winter Wheat ◽

Microsatellite Markers ◽

Wheat Cultivars ◽

Winter Wheat Cultivars

Download Full-text

Isolate Virulence and Cultivar Response in the Winter Wheat: Pyrenophora tritici-repentis (Tan Spot) Pathosystem in Oklahoma

The Plant Pathology Journal ◽

10.5423/ppj.oa.01.2021.0012 ◽

2021 ◽

Vol 37 (4) ◽

pp. 339-346

Author(s):

Kazi A. Kader ◽

Robert M. Hunger ◽

Mark E. Payton

Keyword(s):

Cluster Analysis ◽

Leaf Area ◽

Tan Spot ◽

Wheat Cultivars ◽

Cultivar Resistance ◽

Wheat Varieties ◽

Pyrenophora Tritici Repentis ◽

Greenhouse Study ◽

No Till ◽

Increased Susceptibility

Prevalence of tan spot of wheat caused by the fungus Pyrenophora tritici-repentis has become more prevalent in Oklahoma as no-till cultivation in wheat has increased. Hence, developing wheat varieties resistant to tan spot has been emphasized, and selecting pathogen isolates to screen for resistance to this disease is critical. Twelve isolates of P. tritici-repentis were used to inoculate 11 wheat cultivars in a greenhouse study in splitplot experiments. Virulence of isolates and cultivar resistance were measured in percent leaf area infection for all possible isolate x cultivar interactions. Isolates differed significantly (P < 0.01) in virulence on wheat cultivars, and cultivars differed significantly in disease reaction to isolates. Increased virulence of isolates detected increased variability in cultivar response (percent leaf area infection) (r = 0.56, P < 0.05) while increased susceptibility in cultivars detected increased variance in virulence of the isolates (r = 0.76, P < 0.01). A significant isolate × cultivar interaction indicated specificity between isolates and cultivars, however, cluster analysis indicated low to moderate physiological specialization. Similarity in wheat cultivars in response to pathogen isolates also was determined by cluster analysis. The use of diverse isolates of the fungus would facilitate evaluation of resistance in wheat cultivars to tan spot.

Download Full-text

Evaluation and Association Mapping of Resistance to Tan Spot and Stagonospora Nodorum Blotch in Adapted Winter Wheat Germplasm

Plant Disease ◽

10.1094/pdis-11-14-1131-re ◽

2015 ◽

Vol 99 (10) ◽

pp. 1333-1341 ◽

Cited By ~ 19

Author(s):

Zhaohui Liu ◽

Ibrahim El-Basyoni ◽

Gayan Kariyawasam ◽

Guorong Zhang ◽

Allan Fritz ◽

...

Keyword(s):

United States ◽

Winter Wheat ◽

Association Mapping ◽

Great Plains ◽

The United States ◽

Tan Spot ◽

Stagonospora Nodorum ◽

Northern Great Plains ◽

Stagonospora Nodorum Blotch ◽

Pyrenophora Tritici Repentis

Tan spot and Stagonospora nodorum blotch (SNB), often occurring together, are two economically significant diseases of wheat in the Northern Great Plains of the United States. They are caused by the fungi Pyrenophora tritici-repentis and Parastagonospora nodorum, respectively, both of which produce multiple necrotrophic effectors (NE) to cause disease. In this work, 120 hard red winter wheat (HRWW) cultivars or elite lines, mostly from the United States, were evaluated in the greenhouse for their reactions to the two diseases as well as NE produced by the two pathogens. One P. nodorum isolate (Sn4) and four Pyrenophora tritici-repentis isolates (Pti2, 331-9, DW5, and AR CrossB10) were used separately in the disease evaluations. NE sensitivity evaluation included ToxA, Ptr ToxB, SnTox1, and SnTox3. The numbers of lines that were rated highly resistant to individual isolates ranged from 11 (9%) to 30 (25%) but only six lines (5%) were highly resistant to all isolates, indicating limited sources of resistance to both diseases in the U.S. adapted HRWW germplasm. Sensitivity to ToxA was identified in 83 (69%) of the lines and significantly correlated with disease caused by Sn4 and Pti2, whereas sensitivity to other NE was present at much lower frequency and had no significant association with disease. As expected, association mapping located ToxA and SnTox3 sensitivity to chromosome arm 5BL and 5BS, respectively. A total of 24 potential quantitative trait loci was identified with −log (P value) > 3.0 on 12 chromosomes, some of which are novel. This work provides valuable information and tools for HRWW production and breeding in the Northern Great Plains.

Download Full-text