The Identification of Two New Races of<i>Pyrenophora tritici-repentis</i>from the Host Center of Diversity Confirms a One-to-One Relationship in Tan Spot of Wheat

Lamari, L.; Strelkov, Stephen E.; Yahyaoui, A.; Orabi, Jihad; Smith, Richard B.

doi:10.1094/phyto.2003.93.4.391

Cited by 195 publications

(266 citation statements)

References 26 publications

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“…Virulence variation in P. tritici-repentis has been observed based on an isolate's ability to produce necrosis and/ or chlorosis symptoms on appropriate wheat differential genotype. So far, the isolates from wheat and alternative host plants have been grouped into eight races [ 2,[9][10][11] and race 1 was the most prevalent race observed in Africa, Asia, Europe, North and South America [2,9,[11][12][13][14][15]. Further, P. tritici-repentis produces three host-selective toxins, Ptr ToxA, Ptr ToxB, and Ptr ToxC, which are associated with necrosis and chlorosis symptoms in toxins sensitive wheat genotypes [11,[16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Race Diversity of Pyrenophora tritici-repentis in South Dakota and Response of Predominant Wheat Cultivars to Tan Spot

Abdullah¹,

Sk²,

Ali³

2017

J Plant Pathol Microbiol

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The fungus Pyrenophora tritici-repentis (Ptr) causing tan spot (TS) is an important pathogen of wheat in the US Northern-Great-Plains. Knowledge of physiological variation in the pathogen population is essential in the development of durable TS resistant cultivars. Eight Ptr races have been identified based on three host selective toxins (Ptr ToxA/Ptr ToxB/Ptr ToxC), which are associated with necrosis and chlorosis symptoms. The information about Ptr race structure and reaction of wheat cultivars grown in SD to tan spot is scarcely available. In this study, 569 isolates of Ptr collected from wheat were genotyped for Ptr ToxA and Ptr ToxB genes and a subset of 134 isolates were evaluated for their race identity on a wheat differential set. Ptr ToxA and Ptr ToxB genes were amplified in 89.6% and 0.4% isolates, respectively. The remaining 57 (10%) isolates lacked both toxins genes. The characterization of 134 isolates exhibited diverse race structure with 74.6%, 18.7%, 1.49% , and <1% isolates categorized as race 1, 4, 5, and 2, respectively. Another six (4.5%) isolates behaved like race 2 but lacked Ptr ToxA gene, hence could not fit under the currently known eight races. Our results determine the diversity of Ptr population that exists in SD and establish the presence of race 5 in SD for the first time. Since races 1 and 5 are most prevalent in the region, we screened 45 most predominant wheat cultivars against these races and Ptr ToxA. We observed eleven cultivars resistant or moderately resistant to both races, however, seven spring wheat cultivars showed susceptibility to both races 1 and 5. Continued cultivation of wheat cultivars susceptible to both races could play a role in the establishment and development of new races. Continuous germplasm enhancement and periodically monitoring Ptr population can help in better TS management.

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Section: Introductionmentioning

confidence: 99%

Race Diversity of Pyrenophora tritici-repentis in South Dakota and Response of Predominant Wheat Cultivars to Tan Spot

Abdullah¹,

Sk²,

Ali³

2017

J Plant Pathol Microbiol

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“…Toxins appear to act as pathogenicity factors (Orolaza et al 1995;Ciuffetti et al 2010). P. tritici-repentis ability to induce two distinct symptoms, tan necrosis and extensive chlorosis, on a set of differential wheat varieties is the basis of distinguishing eight P. tritici-repentis races (Lamari et al 2003). Each race is differentiated by the expression of one toxin or a combination of Ptr ToxA, PtrToxB and Ptr ToxC toxins.…”

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confidence: 99%

Differentially expressed gene transcripts in wheat and barley leaves upon leaf spot infection

Dumalasová¹,

Svobodová²,

Hanzalová³

2012

CZECH J GENET PLANT

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A cDNA library was created on the basis of transcripts that were generated during the process of infection of wheat and barley with Pyrenophora tritici-repentis or P. teres. Due to the time course of infection assays, the leaves were collected at various intervals after inoculation until 100 h after inoculation. We compared the temporal development of the two pathogens, as well as the effect of varieties of the same crop species, and differences among isolates of a single pathogen. The appressoria and vesicular structures developed more rapidly in barley varieties inoculated by P. teres than in wheat varieties inoculated by P. tritici-repentis. The lower level of susceptibility of the wheat variety Globus and the barley variety Heris to P. tritici-repentis and P. teres, respectively, was apparent from 12 h after infection. Information on changes in expression profiles during pathogenesis and on the clones that could be functionally assigned to the known gene sequences is presented. Out of the 360 transcript derived fragments (TDFs) produced in the barley-P. teres pathosystem in our trials, 62% were specific to the plant-pathogen interaction. In the wheat-P. tritici-repentis pathosystem 291 TDFs occurred, 63% were specific to the plant-pathogen interaction.

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“…All the isolates produced necrosis on Glenlea, which is indication of presence of Ptr ToxA in the culture filtrate. Although, race 1 isolates produces both Ptr ToxA and Ptr ToxC, since Ptr ToxC is highly unstable and gets lost in culture filtrate (Lamari et al 2003), we failed to observe Ptr ToxC induced symptoms i.e. …”

Section: Resultsmentioning

confidence: 63%

“…However, Lamari et al (1995) proposed a race designation based system to describe isolates of P. tritici-repentis on the basis of their ability to induce tan necrosis and/or extensive chlorosis on a set of differential wheat cultivars. Presently isolates of the tan spot fungus are classified into 8 races (Lamari et al 2003). Three races 2, 3, and 5 can be designated as basic races while other races based on the reaction on the standard differential set are different combinations of the basic races with the exception of race 4 which is avirulent (Singh et al 2010).…”

Section: S103mentioning

confidence: 99%

Evaluation of CIMMYT germplasm for resistance to leaf spotting diseases of wheat

Singh¹,

Duveiller²,

Singh³

2011

CZECH J GENET PLANT

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Abstract:The leaf spotting disease complex is a major biotic constrain in enhancing grain production in the major wheat growing regions. Two leaf spotting diseases, tan spot, caused by an ascomycete fungus Pyrenophora tritici-repentis, and Stagonospora nodorum blotch besides causing average yield losses of 5-10%, cause significant losses in grain quality by red smudge, black point and grain shriveling. Conservation agriculture in combination with wheat monoculture involving cultivation of susceptible cultivars has resulted in frequent onset of leaf spots epidemics worldwide. Development of resistant wheat cultivars, in conjunction with crop rotation, will provide an effective, economical, and environmentally safe means of controlling leaf spot. International Maize and Wheat Improvement Center (CIMMYT), Mexico has initiated major efforts to mitigate the threat of tan spot. Efforts include screening of wheat germplasm, identification of new sources of resistance, characterization of new tan spot resistance genes through classical and molecular genetic analysis, incorporation of resistance into adapted cultivars, and assessing the variability in the tan spot fungus. Screening studies reveal that elite CIMMYT germplasm has high level of resistance to tan spot caused by P. tritici-repentis race 1. These germplasm have diverse genetic make-up and the resistance is likely broad based. Association mapping studies done with CIMMYT germplasm reconfirmed the presence of previously identified genomic regions for tan spot resistance; however, novel genomic regions on long arm of chromosomes 6A and 7B have also been identified. Studies done to date indicate that CIMMYT germplasm possess high level diverse genetic based resistance to tan spot of wheat. Efforts are in place to develop desired wheat cultivars with tan spot resistance. Virulence studies indicate presence of P. tritici-repentis race 1 only with some variability in level of toxin Ptr ToxA produced in each of the 76 isolates studied.

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The Identification of Two New Races ofPyrenophora tritici-repentisfrom the Host Center of Diversity Confirms a One-to-One Relationship in Tan Spot of Wheat

Cited by 195 publications

References 26 publications

Race Diversity of Pyrenophora tritici-repentis in South Dakota and Response of Predominant Wheat Cultivars to Tan Spot

Race Diversity of Pyrenophora tritici-repentis in South Dakota and Response of Predominant Wheat Cultivars to Tan Spot

Differentially expressed gene transcripts in wheat and barley leaves upon leaf spot infection

Evaluation of CIMMYT germplasm for resistance to leaf spotting diseases of wheat

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