Evaluation of Wheat Germplasm for Resistance to Leaf Rust (Puccinia triticina) and Identification of the Sources of Lr Resistance Genes Using Molecular Markers.

Alma Kokhmetova,Angelina Malysheva,Ardak Bolatbekova,Danna Zhanuzak,Zhenis Keishilov,Madina Kumarbayeva,Makpal Atishova,Shynbolat Rsaliyev

doi:10.3390/plants10071484

Abstract

Leaf rust, caused by Puccinia triticina (Ptr), is a significant disease of spring wheat spread in Kazakhstan. The development of resistant cultivars importantly requires the effective use of leaf rust resistance genes. This study aims to: (i) determine variation in Ptr population using races from the East Kazakhstan, Akmola, and Almaty regions of Kazakhstan; (ii) examine resistance during seedling and adult plant stages; and (iii) identify the sources of Lr resistance genes among the spring wheat collection using molecular markers. Analysis of a mixed population of Ptr identified 25 distinct pathotypes. Analysis of these pathotypes using 16 Thatcher lines that are near-isogenic for leaf rust resistance genes (Lr) showed different virulence patterns, ranging from least virulent “CJF/B” and “JCL/G” to highly virulent “TKT/Q”. Most of the pathotypes were avirulent to Lr9, Lr19, Lr24, and Lr25 and virulent to Lr1, Lr2a, Lr3ka, Lr11, and Lr30. The Ptr population in Kazakhstan is diverse, as indicated by the range of virulence observed in five different races analyzed in this study. The number of genotypes showed high levels of seedling resistance to each of the five Ptr races, thus confirming genotypic diversity. Two genotypes, Stepnaya 62 and Omskaya 37, were highly resistant to almost all five tested Ptr pathotypes. Stepnaya 62, Omskaya 37, Avangard, Kazakhstanskaya rannespelaya, and Kazakhstanskaya 25 were identified as the most stable genotypes for seedling resistance. However, most of the varieties from Kazakhstan were susceptible in the seedling stage. Molecular screening of these genotypes showed contrasting differences in the genes frequencies. Among the 30 entries, 22 carried leaf rust resistance gene Lr1, and two had Lr9 and Lr68. Lr10 and Lr28 were found in three and four cultivars, respectively. Lr19 was detected in Omskaya 37. Two single cultivars separately carried Lr26 and Lr34, while Lr37 was not detected in any genotypes within this study. Field evaluation demonstrated that the most frequent Lr1 gene is ineffective. Kazakhstanskaya 19 and Omskaya 37 had the highest number of resistance genes: three and four Lr genes, respectively. Two gene combinations (Lr1, Lr68) were detected in Erythrospermum 35 and Astana. The result obtained may assist breeders in incorporating effective Lr genes into new cultivars and developing cultivars resistant to leaf rust.

Highlights

Central Asia, including Kazakhstan, is a significant player in regional and global food security, producing most of the grain traded in the region, with total area sown to wheat in Kazakhstan representing over 85% of total cereal production [1]
Use of 16 TcLr-lines helped to identify 25 virulence phenotypes of P. triticina from leaf rust-infected leaf samples that were collected in East Kazakhstan (East), Akmola (North), and Almaty (Southeast) regions of Kazakhstan during the 2019 and 2020 seasons (Table 1)
Leaf rust is a perennial problem for spring and winter wheat in Central Asia, including Kazakhstan [14,15,35], and Puccinia triticina (Ptr) populations are diverse and highly virulent [27,30]

Summary

Introduction

Central Asia, including Kazakhstan, is a significant player in regional and global food security, producing most of the grain traded in the region, with total area sown to wheat in Kazakhstan representing over 85% of total cereal production [1]. One of the main reasons for the reduction in the yield of wheat in Kazakhstan is the disease with airborne infection. As a part of the pathogenic complex of wheat in Kazakhstan, is taken by rusts (yellow, stem, and leaf rust) [2,3,4,5], as well as leaf spot diseases (tan spot and Septoria) [6,7,8,9,10,11]. Puccinia triticina (Ptr), is found in major wheat-growing regions of the world and is a leading cause of yield loss in wheat. It caused serious damage to both yield and quality. The disease causes 21.5% of yield losses in wheat globally [13]

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