Abstract
Tan spot, caused by the fungus Pyrenophora tritici-repentis (Ptr), is a severe foliar disease of wheat (Triticum aestivum L.). Improving genetic resistance is a durable strategy to reduce Ptr-related losses. Here, we dissected Ptr-infection’s genetic basis in 372 European wheat varieties via simple sequence repeats (SSRs) plus 35k and 90k single nucleotide polymorphism (SNP) marker platforms. In our phenotypic data analyses, Ptr infection showed a significant genotypic variance and a significant negative correlation with plant height. Genome-wide association studies revealed a highly quantitative nature of Ptr infection and identified two quantitative trait loci (QTL), viz., QTs.ipk-7A and QTs.ipk-7B, which imparted 21.23 and 5.84% of the genotypic variance, respectively. Besides, the Rht-D1 gene showed a strong allelic influence on the infection scores. Due to the complex genetic nature of the Ptr infection, the potential of genome-wide prediction (GP) was assessed via three different genetic models on individual and combined marker platforms. The GP results indicated that the marker density and marker platforms do not considerably impact prediction accuracy (~40–42%) and that higher-order epistatic interactions may not be highly pervasive. Our results provide a further understanding of Ptr-infection’s genetic nature, serve as a resource for marker-assisted breeding, and highlight the potential of genome-wide selection for improved Ptr resistance.
Highlights
Tan spot, known as the yellow leaf spot, is a severe disease of wheat worldwide.Caused by the fungal pathogen Pyrenophora tritici-repentis, (Ptr; Died.) anamorph Drechslera tritici-repentis (Dtr; Died.) Shoem
The tan spot (Ptr) infection assessment on 372 wheat varieties registered primarily for European markets was performed in replicated field trials
genome-wide prediction (GP) based on markers collectively from every platform
Summary
Known as the yellow leaf spot, is a severe disease of wheat worldwide.Caused by the fungal pathogen Pyrenophora tritici-repentis, (Ptr; Died.) anamorph Drechslera tritici-repentis (Dtr; Died.) Shoem. Known as the yellow leaf spot, is a severe disease of wheat worldwide. Helminthosporium tritici-repentis), the Ptr infection is mainly diagnosed by tan-colored necrotic lesions with yellow margins that are often surrounded by chlorotic haloes on susceptible wheat leaves. Dead leaf tissue areas translate to plant stress and eventually yield loss [1]. The yield losses—that may reach up to 50%—are mainly attributed to the reduction in (1) leaf area index, (2) dry matter accumulation, and (3) the number of reproductive tillers [3,4]. Reduced kernel size, kernel weight, and the number of kernels per ear were reported to be the main drivers of Ptr-associated yield losses [5]
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