THE PATHOGENICITY OF NEW RACES OF WHEAT STEM RUST TO ADULT PLANTS OF RESISTANT VARIETIES

In a field experiment the wheat cultivars Glenwari, Exchange, Thatcher, Warigo, Idaed 59, and Hopps were assessed as having slow rusting abilities when artificially inoculated with a mixture of 22 physiologic races of stem rust. Resistance that resulted in slow rusting was demonstrated in growth cabinets with adult plants of these six cultivars after standardized inoculation with three stem rust races followed by uniform incubation and growth conditions. The investigation revealed that the following different kinds of resistance were involved: (1) 'specific' resistance effective against race C17 was observed in tests with seedlings and adult plants of Thatcher, Hopps, and Idaed 59; (2) low receptivity was observed in tests with adult plants of Glenwari, Warigo. Hopps, and Idaed 59; and (3) low urediospore production per pustule was evident in tests of the cultivar Exchange. The resistance of the cultivar Thatcher appeared complex, involving slow and nonuniform pustule development.Resistance expressed as low receptivity and low urediospore productivity varied in effectiveness against different physiologic races. In many instances significant interactions occurred between cultivars and races. Temperature changes appeared to affect the expression of resistance in many race–cultivar combinations. Thus, this type of resistance does not fit the definition of horizontal resistance proposed by van der Plank. Nevertheless, field investigations indicate that the resistance is effective against many rust races and could be potentially valuable in breeding programs.

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Principal approaches and achievements in studying race composition of wheat stem rust

Vavilov Journal of Genetics and Breeding ◽

10.18699/vj18.439 ◽

2019 ◽

Vol 22 (8) ◽

pp. 967-977 ◽

Cited By ~ 4

Author(s):

A. S. Rsaliyev ◽

Sh. S. Rsaliyev

Keyword(s):

Stem Rust ◽

Wheat Stem Rust ◽

Wheat Varieties ◽

Differential Set ◽

Northern Regions ◽

Disease Agent ◽

Commercially Important ◽

New Races ◽

Intraspecies Structure

Wheat stem rust caused by the biotrophic fungus Puccinia graminis f. sp. tritici is a dangerous disease that seriously damages the economics in many countries of the world. The review contains information about epidemics of wheat stem rust and causes of their emergence worldwide. Recently wheat stem rust epidemics have been recorded in the northern regions of Kazakhstan and on the territories adjacent to Omsk Region of Russia. It has been shown that severe wheat stem rust epidemics occur mainly due to the emergence of new virulent races of the disease agent and to growing susceptible wheat cultivars. New methods of studying the race composition of the fungus are described as well as the use of the previous and current diﬀerential sets for race determination of P. graminis f. sp. tritici. The results of developing molecular markers and assessing their eﬀectiveness in studying stem rust races are presented. Wheat stem rust races dominant in major grain-growing countries of the globe and their typical peculiarities are described. The paper contains information on identifcation of race Ug99 and of its variations including data on areas of their dissemination and on their virulence to Sr-resistance genes. The existence and emergence of other races of the agent potentially dangerous for commercially important genes for stem rust resistance is also described. Currently in nature strongly virulent races of P. graminis f. sp. tritici are circulating with wide geographical coverage and their virulence is absolutely diﬀerent from the virulence of race Ug99. Historical and modern data on studying the race composition of the pathogen in Kazakhstan are summarized. It is stated that the use of the old standard diﬀerential set and an incomplete North American system of race nomenclature in experiments prevents measuring similarity between Kazakhstani races and the worldwide known races of the pathogen. It has been shown that there is a need to continue studies on the intraspecies structure of the disease agent’s population in Kazakhstan with the use of the modern diﬀerential set, on determination of race composition and ways of emergence of new races potentially dangerous for commercial wheat varieties.

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SOURCES OF RESISTANCE TO NORTH CAUCASIAN STEM RUST POPULATION AMONG SOFT WHEAT SAMPLES FROM THE ALL-RUSSIAN PLANT RESEARCH INSTITUTE COLLECTION

Vestnik of the Russian agricultural science ◽

10.30850/vrsn/2020/4/50-53 ◽

1970 ◽

pp. 50-53

Author(s):

G. V. Volkova ◽

О. О. Miroshnichenko ◽

Е. V. Gladkova ◽

А. V. Dement’ev ◽

Е. V. Zuev

Keyword(s):

Stem Rust ◽

Plant Genetic Resources ◽

Triticum Aestivum L ◽

Soft Wheat ◽

Artificial Infection ◽

Sources Of Resistance ◽

Wheat Stem Rust ◽

The North ◽

Resistant Varieties ◽

Russian Plant

Wheat stem rust (pathogen Puccinia graminis Pers. f. sp. tritici) is a dangerous disease that affects crops. The pathogen causes many ruptures of the epidermis of the stem. With a significant development of the pathogen, lodging of wheat crops is possible, the yield sharply decreases due to the so-called outflow of grain. The use of pathogen resistant varieties is one of the most effective wheat protection methods. In 2018-2019, against the background of artificial infection with P. graminis, 263 samples of soft wheat (Triticum aestivum L.) from the collection of the Vavilov All - Russian Institute of Plant Genetic Resources (VIR) were evaluated, of which 186 were spring and 77 were winter. Varieties and lines of soft wheat were represented from 27 countries and mostly from Russia (44.9 % of the number studied). 56 sources of resistance to the North Caucasian population of P. graminis were identified, which are recommended for use in selection for immunity. A larger number of P. graminis-resistant specimens were isolated from Russia – 26 and Canada-9. Of particular interest for breeding are samples of soft wheat that were absolutely resistant to artificial infection with the pathogen: Stolypenskaya 2 (K - 66388, Russia, Omsk region), Grenada (K-66399, Russia, Tyumen region), Primorskaya 50 (K-66409, Russia, Primorsky Krai), Vishivanka (K-65257, Ukraine), K-66443 (Georgia), Shortandinskaya 2014 (K-66424, Kazakhstan), Chi Mai 1 (K-66440, China), byrsa (K-65852, Tunisia), Lovitt (K-66204, Canada), Nil Thatcher Lr35 (K-66207, Canada), Harding (K-66081, USA), Juchi F2000 (K-66252, Mexico).

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Presence of a Sexual Population of Puccinia graminis f. sp. tritici in Georgia Provides a Hotspot for Genotypic and Phenotypic Diversity

Phytopathology ◽

10.1094/phyto-06-19-0186-r ◽

2019 ◽

Vol 109 (12) ◽

pp. 2152-2160 ◽

Cited By ~ 5

Author(s):

Pablo D. Olivera ◽

Zoya Sikharulidze ◽

Rusudan Dumbadze ◽

Les J. Szabo ◽

Maria Newcomb ◽

...

Keyword(s):

Stem Rust ◽

Phenotypic Diversity ◽

Genotypic Diversity ◽

Puccinia Graminis ◽

Alternate Host ◽

Wheat Stem Rust ◽

Caucasus Region ◽

Sexual Recombination ◽

New Races ◽

Pathogen Populations

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is a re-emerging disease exemplified by recent epidemics caused by new virulent races. Understanding the sources and origins of genetic variations in the pathogen populations globally can facilitate the development of better strategies in disease management. We analyzed 68 wheat stem rust samples collected between 2013 and 2015 from Georgia where stem rust incidences are frequent and the alternate host, common barberry, is present. A total of 116 single-pustule isolates were derived and evaluated on stem rust differential lines to determine the virulence phenotypes and 23 races were identified, many of which were detected for the first time. Unique virulence combinations including, Sr22+Sr24 and Sr13b+Sr35+Sr37 were detected. These virulence combinations pose new challenges to breeding programs because many of these genes are used in breeding for resistance to the Ug99 race group. Sixty-one isolates were genotyped using a custom single-nucleotide polymorphism chip and 17 genotypes were identified. The 2013 isolates contained 11 multilocus genotypes compared with isolates of 2014 and 2015, with five and three genotypes, respectively. The higher levels of virulence and genotypic diversity observed in the 2013 samples strongly indicated that sexual recombination occurs in the Georgian P. graminis f. sp. tritici population, and that the Caucasus region of Eurasia may be an important source of new races. [Formula: see text] Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

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Genomic Dissection of Nonhost Resistance to Wheat Stem Rust in Brachypodium distachyon

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-08-18-0220-r ◽

2019 ◽

Vol 32 (4) ◽

pp. 392-400 ◽

Cited By ~ 1

Author(s):

Rafael Della Coletta ◽

Candice N. Hirsch ◽

Matthew N. Rouse ◽

Aaron Lorenz ◽

David F. Garvin

Keyword(s):

Stem Rust ◽

Brachypodium Distachyon ◽

Durable Resistance ◽

Future Research ◽

Nonhost Resistance ◽

Wheat Stem Rust ◽

Causal Pathogen ◽

New Races ◽

Molecular Marker Analysis ◽

Model Grass

The emergence of new races of Puccinia graminis f. sp. tritici, the causal pathogen of wheat stem rust, has spurred interest in developing durable resistance to this disease in wheat. Nonhost resistance holds promise to help control this and other diseases because it is durable against nonadapted pathogens. However, the genetic and molecular basis of nonhost resistance to wheat stem rust is poorly understood. In this study, the model grass Brachypodium distachyon, a nonhost of P. graminis f. sp. tritici, was used to genetically dissect nonhost resistance to wheat stem rust. A recombinant inbred line (RIL) population segregating for response to wheat stem rust was evaluated for resistance. Evaluation of genome-wide cumulative single nucleotide polymorphism allele frequency differences between contrasting pools of resistant and susceptible RILs followed by molecular marker analysis identified six quantitative trait loci (QTL) that cumulatively explained 72.5% of the variation in stem rust resistance. Two of the QTLs explained 31.7% of the variation, and their interaction explained another 4.6%. Thus, nonhost resistance to wheat stem rust in B. distachyon is genetically complex, with both major and minor QTLs acting additively and, in some cases, interacting. These findings will guide future research to identify genes essential to nonhost resistance to wheat stem rust.

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Determination of the Role of Berberis spp. in Wheat Stem Rust in China

Plant Disease ◽

10.1094/pdis-09-14-0928-re ◽

2015 ◽

Vol 99 (8) ◽

pp. 1113-1117 ◽

Cited By ~ 4

Author(s):

Jie Zhao ◽

Shilei Zhao ◽

Xianming Chen ◽

Zhiyan Wang ◽

Long Wang ◽

...

Keyword(s):

Stem Rust ◽

Rust Fungus ◽

Wheat Stem Rust ◽

Wheat Seedlings ◽

Detectable Rate ◽

New Races ◽

Relationship Of ◽

The Relationship

Previous studies on the relationship of barberry (Berberis spp.) and wheat stem rust suggested that, although some barberry species can serve as alternate hosts for the stem rust fungus Puccinia graminis f. sp. tritici, barberry plants play no role in wheat stem rust development and virulence variation of P. graminis f. sp. tritici in China. In the present study, severe rust infections on Berberis shensiana, B. brachypoda, B. potaninii, B. soulieana, and B. aggregata were observed during field surveys in 2011 and 2012. Through artificial inoculation of wheat seedlings (‘Mingxian 169’) under greenhouse conditions with aeciospores from naturally infected barberry plants, 185 isolates of P. graminis f. sp. tritici were obtained. From the 27 selected isolates that were tested on a set of wheat genotypes used to differentiate P. graminis f. sp. tritici races in China, 18 races were identified, of which 8 races were new and others were of Chinese 21 and 34 race groups. In addition to the information of virulence or avirulence patterns on the Chinese differentials, none of the races were virulent to resistance gene Sr31. The virulence frequencies based on individual Sr genes or differentials ranged from 0 to 96%. Using molecular markers for P. graminis f. sp. tritici, 75 of 4,036 samples of single aecia were identified as P. graminis f. sp. tritici. The low detectable rate of P. graminis f. sp. tritici was verified based on both infection and molecular marker tests. This observation may be correlated with the low levels of wheat stem rust in the surveyed regions. This study shows that P. graminis f. sp. tritici can produce new races through sexual reproduction on Berberis spp. in China.

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