scholarly journals Necrotrophic Fungus Pyrenophora tritici-repentis Triggers Expression of Multiple Resistance Components in Resistant and Susceptible Wheat Cultivars

2021 ◽  
Vol 37 (2) ◽  
pp. 99-114
Author(s):  
Ethan J. Andersen ◽  
Madhav P. Nepal ◽  
Shaukat Ali
Keyword(s):  
Multiple Resistance ◽  
Wheat Cultivars ◽  
Resistance Components ◽  
Pyrenophora Tritici Repentis

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

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.

scholarly journals Emergence of Tan Spot Disease Caused by Toxigenic Pyrenophora tritici-repentis in Australia Is Not Associated with Increased Deployment of Toxin-Sensitive Cultivars

2008 ◽  
Vol 98 (5) ◽  
pp. 488-491 ◽  
Author(s):  
R. P. Oliver ◽  
M. Lord ◽  
K. Rybak ◽  
J. D. Faris ◽  
P. S. Solomon
Keyword(s):  
The United States ◽  
Tan Spot ◽  
Wheat Cultivars ◽  
Tillage Practices ◽  
Pyrenophora Tritici Repentis ◽  
South Wales ◽  
Glume Blotch ◽  
Wheat Gene ◽  
Serious Disease ◽  
Wheat Lines

The wheat disease tan (or yellow leaf) spot, caused by Pyrenophora tritici-repentis, was first described in the period 1934 to 1941 in Canada, India, and the United States. It was first noted in Australia in 1953 and only became a serious disease in the 1970s. The emergence of this disease has recently been linked to the acquisition by P. tritici-repentis of the ToxA gene from the wheat leaf and glume blotch pathogen, Stagonospora nodorum. ToxA encodes a host-specific toxin that interacts with the product of the wheat gene Tsn1. Interaction of ToxA with the dominant allele of Tsn1 causes host necrosis. P. tritici-repentis races lacking ToxA give minor indistinct lesions on wheat lines, whereas wheat lines expressing the recessive tsn1 are significantly less susceptible to the disease. Although the emergence and spread of tan spot had been attributed to the adoption of minimum tillage practices, we wished to test the alternative idea that the planting of Tsn1 wheat lines may have contributed to the establishment of the pathogen in Australia. To do this, wheat cultivars released in Australia from 1911 to 1986 were tested for their sensitivity to ToxA. Prior to 1941, 16% of wheat cultivars were ToxA-insensitive and hence, all other factors being equal, would be more resistant to the disease. Surprisingly, only one of the cultivars released since 1940 was ToxA insensitive, and the area planted to ToxA-insensitive cultivars varied from 0 to a maximum of only 14% in New South Wales. Thus, the majority of the cultivars were ToxA-sensitive both before and during the period of emergence and spread of the disease. We therefore conclude that the spread of P. tritici-repentis in Australia cannot be causally linked to the deployment of ToxA-sensitive cultivars.

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

Plant Disease ◽  
2010 ◽  
Vol 94 (2) ◽  
pp. 229-235 ◽  
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.

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

2021 ◽  
Author(s):  
Kazi A. Kader ◽  
Robert M. Hunger ◽  
Aswathy Sreedharan ◽  
Stephen M. Marek
Keyword(s):  
Genetic Variability ◽  
Winter Wheat ◽  
Genetic Relationships ◽  
Principal Component ◽  
Tan Spot ◽  
Pcr Analysis ◽  
Wheat Cultivars ◽  
Disease Symptoms ◽  
Pyrenophora Tritici Repentis ◽  
Race 1

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.

scholarly journals ToxA–Tsn1 Interaction for Spot Blotch Susceptibility in Indian Wheat: An Example of Inverse Gene-for-Gene Relationship

Plant Disease ◽  
2020 ◽  
Vol 104 (1) ◽  
pp. 71-81 ◽  
Author(s):  
Sudhir Navathe ◽  
Punam Singh Yadav ◽  
Ramesh Chand ◽  
Vinod Kumar Mishra ◽  
Neeraj Kumar Vasistha ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Bipolaris Sorokiniana ◽  
Spot Blotch ◽  
Wheat Cultivars ◽  
Pyrenophora Tritici Repentis ◽  
Necrotic Spots ◽  
Parastagonospora Nodorum ◽  
Necrotrophic Effector ◽  
Selection Of ◽  
Gene For Gene

The ToxA–Tsn1 system is an example of an inverse gene-for-gene relationship. The gene ToxA encodes a host-selective toxin (HST) which functions as a necrotrophic effector and is often responsible for the virulence of the pathogen. The genomes of several fungal pathogens (e.g., Pyrenophora tritici-repentis, Parastagonospora nodorum, and Bipolaris sorokiniana) have been shown to carry the ToxA gene. Tsn1 is a sensitivity gene in the host, whose presence generally helps a ToxA-positive pathogen to cause spot blotch in wheat. Cultivars lacking Tsn1 are generally resistant to spot blotch; this resistance is attributed to a number of other known genes which impart resistance in the absence of Tsn1. In the present study, 110 isolates of B. sorokiniana strains, collected from the ME5A and ME4C megaenvironments of India, were screened for the presence of the ToxA gene; 77 (70%) were found to be ToxA positive. Similarly, 220 Indian wheat cultivars were screened for the presence of the Tsn1 gene; 81 (36.8%) were found to be Tsn1 positive. When 20 wheat cultivars (11 with Tsn1 and 9 with tsn1) were inoculated with ToxA-positive isolates, seedlings of only those carrying the Tsn1 allele (not tsn1) developed necrotic spots surrounded by a chlorotic halo. No such distinction between Tsn1 and tsn1 carriers was observed when adult plants were inoculated. This study suggests that the absence of Tsn1 facilitated resistance against spot blotch of wheat. Therefore, the selection of wheat genotypes for the absence of the Tsn1 allele can improve resistance to spot blotch.

Prevalence of ToxA-sensitive alleles of the wheat gene Tsn1 in Australian and Chinese wheat cultivars

2009 ◽  
Vol 60 (4) ◽  
pp. 348 ◽  
Author(s):  
Richard P. Oliver ◽  
Kasia Rybak ◽  
Peter S. Solomon ◽  
Margo Ferguson-Hunt
Keyword(s):  
Recent Survey ◽  
Stagonospora Nodorum ◽  
Wheat Cultivars ◽  
Pyrenophora Tritici Repentis ◽  
Wheat Gene ◽  
Chinese Wheat

A recent survey of worldwide isolates of Stagonospora nodorum showed that all Australian isolates expressed the host-specific toxin ToxA (Stukenbrock and McDonald 2007). In contrast, very few Chinese isolates did. All the Australian Pyrenophora tritici-repentis isolates that were tested expressed ToxA. We therefore postulated that the wheat gene that confers sensitivity to ToxA, Tsn1, would vary in prevalence in wheat cultivars in use in the two countries. Contrary to expectation, 10 out of 21 Chinese cultivars responded to ToxA as did 26 out of 46 Australian cultivars. The result suggests that ToxA has not had a determining effect on the survival of wheat cultivars in either country. They also suggest that despite the widespread use of Tsn1 markers in Australia, sensitive alleles are still commonplace. The removal of sensitive alleles from breeders’ lines could be readily achieved and could significantly affect the resistance of wheat to both diseases.

Leaf spotting reaction of spring common, durum and spelt wheat, and Kamut under organic management in western Canada

2014 ◽  
Vol 94 (5) ◽  
pp. 929-935 ◽  
Author(s):  
M. R. Fernandez ◽  
S. L. Fox ◽  
P. Hucl ◽  
A. K. Singh
Keyword(s):  
Durum Wheat ◽  
Leaf Spot Disease ◽  
Western Canada ◽  
Wheat Cultivars ◽  
Organic Management ◽  
Spelt Wheat ◽  
Conventional Management ◽  
Pyrenophora Tritici Repentis ◽  
Phaeosphaeria Nodorum ◽  
The Common

Fernandez, M. R., Fox, S. L., Hucl, P. and Singh, A. K. 2014. Leaf spotting reaction of spring common, durum and spelt wheat, and Kamut under organic management in western Canada. Can. J. Plant Sci. 94: 929–935. A 3-yr field study (2010 to 2012) was conducted in southwest Saskatchewan to determine the reaction of common, durum and spelt wheat cultivars currently registered in western Canada, and of Kamut wheat, to the leaf spot disease complex (LS) under organic management. The genotypes selected for this study are often grown by organic producers in this region. Overall, the most common LS diseases observed had been observed in previous studies under conventional management in the same area. For all 3 yr, common wheat cultivars with the highest LS scores were AC Barrie, CDC Go, Superb, and Unity, while those with the lowest scores were AC Andrew, CDC Bounty and Lillian. For durum wheat, Kyle had overall the greatest LS scores. CDC Zorba had lower LS scores than the other spelt wheat, CDC Origin, and it also had the lowest LS levels of all genotypes in this study. Kamut wheat was similar to the common and durum wheat cultivars for LS severity. The relative presence of the most common LS pathogens isolated (Pyrenophora tritici-repentis, Phaeosphaeria nodorum, Phaeosphaeria avenaria f. sp. triticea, Cochliobolus sativus, Mycosphaerella graminicola) from each of the four wheat species in each of the three years is also presented and discussed.

scholarly journals Reaction of 50 Winter Wheat Cultivars Grown in the Czech   Republic to Pyrenophora tritici-repentis Races 1, 3, and 6

2011 ◽  
Vol 42 (No. 2) ◽  
pp. 31-37
Author(s):  
J. Palicová-Šárová ◽  
A. Hanzalová
Keyword(s):  
Czech Republic ◽  
Winter Wheat ◽  
Moderate Level ◽  
Wheat Cultivars ◽  
Artificial Infection ◽  
The Czech Republic ◽  
Breeding Lines ◽  
Pyrenophora Tritici Repentis ◽  
Winter Wheat Cultivars ◽  
High Level

The reaction of 50 winter wheat cultivars/lines to artificial infection with Pyrenophora tritici-repentis (PTR) races 1, 3, and 6 was studied under greenhouse conditions. The set of tested cultivars/lines included predominantly cultivars registered in the Czech Republic and some new breeding lines. A high level of resistance to P. tritici-repentis was detected in the cultivars Clarus, Rheia, Cubus, SHMK WW 14-92, &Scaron;&aacute;rka, Vlasta and Dromos (SWS 799.14953), susceptible reactions were observed in the cultivars Caphorn, Corsaire, Karolinum, Heroldo (PBIS 00/91), Hedvika, Biscay, Svitava, Barroko (PBIS 00/140) to all three races tested. The majority of the tested cultivars possess a moderate level of resistance to PTRraces 1, 3, and 6. Significant differences were proved not only in the reaction of the tested cultivars but also in the aggressiveness of the three used isolates. &nbsp;

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