Abstract
Pyrenophora tritici-repentis is a causative agent of tan spot in wheat. In recent years, there has been an increasing spread and harmfulness of wheat tan spot. The aim of the research was to study the racial composition of the P. tritici-repentis population in the Republic of Kazakhstan. A collection of 30 common wheat accessions, including promising lines and cultivars from Kazakhstan and CIMMYT–ICARDA, was assessed for resistance to P. tritici- repentis in a greenhouse and characterized using the Xfcp623 molecular marker, diagnostic for the Tsn1 gene. Monosporic isolates of P. tritici-repentis isolated from the southeastern region were assigned to certain races based on the manifestation of symptoms of necrosis/chlorosis on standard differentials (Glenlea, 6B662, 6B365). Five races of P. tritici-repentis have been identified, including races 1, 2, 3, 7 and 8. It has been shown that races 1 and 8 of P. tritici-repentis are dominant. As a result of the analysis of the frequency of occurrence of the P. tritici-repentis races, it was found that race 1 (50 %) producing Ptr ToxA and Ptr ToxB and race 8 (35 %) producing Ptr ToxA, Ptr ToxB and Ptr ToxC turned out to be dominant. From a practical point of view, of greatest interest are 16 wheat samples, which demonstrated resistance to race 1 and confirmed insensitivity to Ptr ToxA in a molecular screening. These include eight Kazakhstani (4_PSI, 10204_2_KSI, 10204_3_KSI, 10205_2_KSI, 10205_3_KSI, 605_SP2, 632_SP2, Dana) and seven foreign lines (KR11-20, KR11-03, KR11-9014, 11KR-13, KR11-9025, KR12-07, GN-68/2003). The results of this study are of interest in wheat breeding programs for tan spot resistance.
Highlights
One of the main reasons for the reduction in yield of wheat in Kazakhstan are the diseases with airborne infection
The aim of our research was to study the racial composition of the P. tritici-repentis population from the southeastern region of the Republic of Kazakhstan, as well as to search for sources of resistance to tan spot in the collection of wheat samples
The study of the wheat collection is aimed at finding the sources of resistance to PTR based on the assessment of seedling resistance to the dominant races of the fungus, the study of field resistance and molecular screening to P. tritici-repentis toxins
Summary
One of the main reasons for the reduction in yield of wheat in Kazakhstan are the diseases with airborne infection. Dominant position as a part of the pathogenic complex of wheat in the south and south-east of Kazakhstan took rusts (yellow, stem and leaf rust) (Kokhmetova et al, 2011, 2016b, 2018b; Rsaliyev A.S., Rsaliyev Sh.S., 2018), as well as leaf spot diseases (tan spot and Septoria) (Kokhmetova et al, 2017, 2018a, 2019). The causative agent of wheat tan spot is the fungus Pyrenophora tritici-repentis, which belongs to the class Ascomycetes, the subclass of marsupials, the order Dothidiales, the family Pleorosporaceae. P. tritici-repentis infects more than 60 species of forage and wild-growing grasses (Koishybaev, 2010; Mironenko, Kovalenko, 2018). The source of the primary infection is the ascospores of the fungus, the secondary infection is caused by conidia, which are carried by the wind (Pospekhov, 1989)
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