Resistance of winter wheat varieties to tan spot in the North Caucasus region of Russia

Abstract

Tan spot caused by Pyrenophora tritici-repentis (Died.) Drechsler, in recent years, occupies an increasingly large area on the territory of Russia. Due to the wide distribution and economic significance of this disease, the search for resistant plants to the pathogen is relevant. This paper presents the results of a field assessment for 2017–2019 of 34 regionally distributed winter wheat varieties of Russian selection for resistance to P. tritici-repentis in the North Caucasus region of Russia. Field resistance - the development of the disease up to 30% against the background of artificial infection for three years was shown by 20.5% of the studied varieties. Wheat varieties were assessed for resistance to isolates of tan spot identified as races 1, 3, and 4 in the greenhouse at the seedling stage. The number of resistant accessions for each race was different and ranged from 12 to 20. The 12 varieties showed resistance to race 1, 14 varieties to race 3, 20 varieties to race 4. This research showed that the resistance to tan spot of studied varieties was race-specific. A functional allele of the susceptibility gene Tsn1 to P. tritici-repentis isolates, producing the toxin Ptr ToxA, was diagnosed by PCR method. Of the analyzed 34 varieties, 13 had a dominant allele of the Tsn1 (Tsn1 + ), and 21 had a recessive allele in the tsn1tsn1 homozygous state. All Tsn1 + varieties, and most varieties with recessive alleles tsn1tsn1 , were susceptible to tan spot in the field. Varieties Dolya, Gurt, Lebed and Sila, which showed field resistance, had the tsn1tsn1 genotype. The expected reaction of varieties with different allelic composition of the Tsn1 gene to inoculation with the isolate of race 1, according to the generally accepted model of “gene-to-gene” interaction, did not coincide with that observed in reality, which confirms the results obtained by other authors. Research results demonstrate the effect of weather conditions on the susceptibility of wheat varieties to tan spot. In years with higher humidity and higher average air temperatures, the susceptibility response to the disease was observed in more varieties than in drier years. The studies show that the main part (79.5%) of winter wheat varieties of Russian selection widely zoned in the North Caucasus region of Russia are susceptible to P. tritici-repentis . Varieties that have been resistant to the pathogen in the adult phase in the field for three years and to the pathogen races in which the recessive allele of the tsn1 gene has been identified may be of interest as sources of resistance for developing new disease-resistant varieties.

Influence of the tillage method on the development of leaf diseases of winter wheat

“…tritici Marchal, Pyrenophora tritici-repentis Died., Septoria tritici Rob. et Desm.,) [5][6][7]. For effective protection, it is important to understand the quantitative and qualitative composition of the spores of fungal pathogens (as an indicator of the presence of an aerogenic infection).…”

Varietal Screening of Durum Wheat Varieties for Resistance to Pyrenophora tritici-repentis (Tan Spot) under Field Conditions

“…Disease severity was more important during growth season 2019-2020, compared to the following season because of the difference in humidity, air temperature and rainfall. These research results was demonstrated by Kremneva et al [22], which highlighted the effect of the higher average air temperatures and humidity on the susceptibility response of the most winter wheat varieties compared to drier years. These same weather factors have influenced the onset and development of the pathogen and the host susceptibility level to the disease in different studies of Fernandez et al [69].…”

“…This virulence variability was associated to eight races of Ptr [ 17 ]. The interaction of Ptr-wheat pathosystem follows in general an inverse of the gene-for-gene model [ 14 ] and race-specific [ 22 ]. The distinct races have the ability to produce three host selective toxins (HSTs) known as PtrToxA, PtrToxB, and PtrToxC, which are considered pathogenic factors.…”

Characterization of Pyrenophora tritici-repentis (tan spot of wheat) races in Kazakhstan

“…In contrast, race 6 was found in Algeria and Morocco (Strelkov et al, 2002;Benslimane, 2018;Gamba et al, 2017), while races 7 and 8 were found only in the Middle East, Caucasus and Algeria, and Kazakhstan in 2018 and 2020 (Kokhmetova et al, 2020b;Benslimane, 2018, Ouaar et al, 2022. In 2021, in the North Caucasus region of Russia, races 1, 3 and 4 were identified (Kremneva et al, 2021). Races 2, 4, 5 and 7 were found in Tunisia by Kamel et al (2019).…”