Abstract
Tan spot caused by the fungus Pyrenophora tritici-repentis is an important leaf spot disease in wheat growing areas throughout the world. The study aims to identify wheat germplasm resistant to tan spot based on phytopathological screening and molecular marker analysis. A collection of 64 common wheat germplasms, including cultivars and breeding lines from Kazakhstan and CIMMYT, was assessed for tan spot resistance in greenhouse conditions and characterized using the Xfcp623 molecular marker, diagnostic for the Tsn1 gene. All wheat cultivars/lines varied in their reaction to tan spot isolate race 1, ranging from susceptible to resistant. Most accessions studied (53 %) were susceptible to Ptr race 1. Spring wheat cultivars were more susceptible to race 1 than winter wheat cultivars. As a result of genotyping, an insensitive reaction to Ptr ToxA was predicted in 41 wheat cultivars (64 %). The tsn1 gene carriers identified included 27 Kazakhstani and 14 CIMMYT cultivars/lines, demonstrating insensitivity to Ptr ToxA. The majority of the Tsn1 genotype were sensitive to race 1 and showed susceptibility to the pathogen in the field. Disease scores from seedling stage positively correlated with field disease ratings. Of particular interest are 27 wheat accessions that demonstrated resistance to spore inoculation by Ptr race 1, were characterized by insensitivity to ToxA and showed field resistance to the pathogen. The results of this study will contribute to wheat breeding programs for tan spot resistance with Marker Assisted Selection using the closely flanking markers.
Highlights
Ensuring food security is the most important priority of Kazakhstan’s economic strategy
The reaction of wheat cultivars and lines representing the range of lesion types to race 1 using rating system (Lamari, Bernier, 1989a) based on two phenotypically distinct symptoms: tan necrosis (N) and chlorosis (C) was carried out
Since it was previously shown that the race 1 is the most prevalent race in Kazakhstan (Zhanarbekova et al, 2005; Maraite et al, 2006; Kokhmetova et al, 2016), in the present study, we searched for carriers of resistance to race 1 and Ptr ToxA toxin among wheat germplasm
Summary
Ensuring food security is the most important priority of Kazakhstan’s economic strategy. Tan spot, caused by the fungus Pyrenophora tritici-repentis (Died.) Drechsler (anamorph), is an important foliar blight disease in temperate and warmer wheat growing areas throughout the world (Duveiller et al, 1998), including Kazakhstan (Koyshibayev, 2018). Under conditions favorable for tan spot development, yield losses can rise beyond 50 % (Rees et al, 1988). This pathogen infects leaf, stem and head tissue resulting in reduced photosynthetic area, increased transpiration and reduced accumulation of organic matter and causes considerable reduction in yield and quality of wheat. Integrated disease control strategies, such as the cultivation of resistant varieties, combined with desired crop rotations and management practices, are the most effective, environmentally friendly and cost-effective tools to combat wheat tan spot (Mikhailova et al, 2012)
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