scholarly journals The Emergence of New Aggressive Leaf Rust Races with the Potential to Supplant the Resistance of Wheat Cultivars

Biology ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 925
Author(s):  
Reda Ibrahim Omara ◽  
Yasser Nehela ◽  
Ola Ibrahim Mabrouk ◽  
Mohsen Mohamed Elsharkawy
Keyword(s):  
Leaf Rust ◽  
Genetic Resistance ◽  
Puccinia Triticina ◽  
Wheat Cultivars ◽  
Physiological Races ◽  
Wheat Leaf ◽  
Host Genetic ◽  
Successful Control ◽  
Location Association

Characterization of the genetic structure and the physiological races of Puccinia triticina is a growing necessity to apply host genetic resistance against wheat leaf rust as a successful control strategy. Herein, we collected and identified about 130 isolates of P. triticina from 16 Egyptian commercial wheat cultivars grown at different locations, over two seasons (2019/2020 and 2020/2021). The 130 isolates of P. triticina were segregated into 17 different physiological races. TTTST and TTTKS were the most common virulent races, whereas TTTST and MTTGT were the most frequent races. The races were classified into three groups, based on their distinct DNA band sizes (150 bp, 200 bp, and 300 bp) after RAPD analysis. The new wheat cultivars (Sakha-94, Sakha-95, and Shandweel-1) infected with the most virulent race (TTTST), Gemmeiza-12, and Misr-3 were resistant to all physiological races. The resistance of these cultivars was mostly due to the presence of Lr19- and Lr28-resistant genes. Our results serve as a warning about emerging aggressive races capable of supplanting resistance to leaf rust, and help in the understanding of the pathotype–cultivar–location association and its role in the susceptibility/resistance of new wheat cultivars to P. triticina.

scholarly journals Dissecting the first phased dikaryotic genomes of the wheat rust pathogen Puccinia triticina reveals the mechanisms of somatic exchange in nature

2019 ◽  
Author(s):  
Jing Qin Wu ◽  
Chongmei Dong ◽  
Long Song ◽  
Christina A. Cuomo ◽  
Robert F. Park
Keyword(s):  
Leaf Rust ◽  
Somatic Hybridization ◽  
Puccinia Triticina ◽  
Genomic Variation ◽  
Hybrid Wheat ◽  
Wheat Cultivars ◽  
Wheat Leaf Rust ◽  
Virulence Evolution ◽  
Rust Pathogen ◽  
Wheat Leaf

AbstractAlthough somatic hybridization (SH) has been proposed as a means of accelerating rust pathogen virulence evolution in the absence of sexual recombination, previous studies are limited to the laboratory and none have revealed how this process happens. Using long-read sequencing, we generated dikaryotic phased genomes and annotations for three Australian field-collected isolates of the wheat leaf rust pathogen (Puccinia triticina; Pt), including a putative asexual hybrid (Pt64) and two putative parental isolates (Pt104 and Pt53; 132-141 Mb,155-176 contigs, N50 of 1.9-2.1 Mb). The genetic dissection based on the high-quality phased genomes including whole-genome alignments, phylogenetic and syntenic analyses along with short-read sequencing of 27 additional Pt isolates convergently demonstrated that Pt64, which rendered several commercial hybrid wheat cultivars susceptible to leaf rust, arose from SH between isolates within the Pt53 and Pt104 lineages. Parentage analysis demonstrated the role of mitotic crossover in the derivation of both nuclei of Pt64. Within HD mating type genes, the distinct specificity regions in Pt64 and the distinct phylogenetic pattern of the remaining admixed isolates suggested high genetic variation in specificity-related regions on the b locus intrinsically associated with the SH. This study not only provided a fundamental platform for investigating genomic variation underlying virulence evolution in one of the most devastating wheat pathogens, but also offered an in-depth understanding of the mechanisms of naturally occurring SH. This asexual mechanism can be broadly exploited by any dikaryotic pathogen to accelerate virulence evolution, and understanding this process is both urgent and crucial for sustainable pathogen control.ImportanceStrategies to manage plant rust pathogens are challenged by the constant emergence of new virulence. Although somatic hybridization has been proposed as a means by which rusts could overcome host resistance rapidly and cause crop loss, there is very little evidence of this process in nature and the mechanisms underlying it are not known. This study generated and analysed the first dikaryotic phased genomes of the wheat leaf rust pathogen, identifying an isolate as a hybrid and for the first time unveiling parasexuality via mitotic crossover in a rust pathogen. The erosion of the resistance of several hybrid wheat cultivars in agriculture by the hybrid rust has important implications for breeding efforts targeting durable resistance and sustained rust control.

scholarly journals Physiologic specialization of wheat leaf rust (Puccinia triticina Eriks.) in the Slovak Republic in 2005, 2006 and 2008

2010 ◽  
Vol 46 (No. 3) ◽  
pp. 114-121 ◽  
Author(s):  
A. Hanzalová ◽  
J. Huszár ◽  
E. Herzová ◽  
P. Bartoš
Keyword(s):  
Leaf Rust ◽  
Slovak Republic ◽  
Puccinia Triticina ◽  
Near Isogenic Lines ◽  
Wheat Cultivars ◽  
Wheat Leaf Rust ◽  
Wheat Leaf ◽  
Winter Wheat Cultivars ◽  
Low Incidence ◽  
Different Parts

In 2005, 2006 and 2008 the virulence of wheat leaf rust population was studied on Thatcher near-isogenic lines with Lr1, Lr2a, Lr2b, Lr2c, Lr3a, Lr9, Lr10, Lr13, Lr15, Lr17, Lr19, Lr21, Lr23, Lr24, Lr26 and Lr28. Samples of leaf rust (141 in total) were obtained from different parts of Slovakia. Resistance gene Lr9 was effective to all tested isolates except three isolates from 2008. No virulence was found to Lr19 and genes Lr24 and Lr28 were also highly effective. Low incidence of virulence to Lr2a was observed. Sixty-five winter wheat cultivars registered in Slovakia were tested with seven leaf rust isolates in the greenhouse. Cultivar Bona Dea was the most resistant of all.

scholarly journals Geographical Distribution of Physiologic Races of Puccinia triticina and Postulation of Resistance Genes in New Wheat Cultivars in Egypt

2012 ◽  
Vol 1 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Nour E. K. Soliman ◽  
Ashraf M. M. Abdelbacki ◽  
Mohammad A.A. Najeeb ◽  
Reda I. Omara
Keyword(s):  
Leaf Rust ◽  
Geographical Distribution ◽  
Resistance Genes ◽  
Puccinia Triticina ◽  
Wheat Cultivars ◽  
Wheat Leaf Rust ◽  
Rust Disease ◽  
Lr Genes ◽  
Wheat Leaf ◽  
Physiologic Races

Knowledge of the geographical distribution for physiologic races of Puccinia triticina and identification of leaf rust resistance genes (Lr ,s) in the recent Egyptian wheat cultivars are essential for maximizing resistance in future-bred cultivars. The  aim   of   this   study   was   to   know   the   status  of resistance in Egyptian wheat cultivars against wheat leaf rust and the most frequent race distributed. Infected samples were collected from five Governorates, i.e.,  Dakahlia,  Kafr el-Sheikh,  Beheira,  Sharqia  and  Sohag comprised the wheat growing area in Egypt. These samples were isolated, purified and identified on the differential stes. Gene postulation was done using fifteen identified races on Egyptian wheat cultivars correlated with Lr genes. Thirty three races identified during three seasons 2009/2010, 2010/2011 and 2011/2012. The most frequent race was TK (10%) followed by race BB (7.58%), PK (6.55%), TT (4.82%), PT (3.79%) and MT (3.44%). Moreover, races; BB, TT and PT were present during three seasons while these races appeared in some Governorates and disappeared in other Governorates. On the other hand, the most frequently occurring gene in ten Egyptian wheat cultivars was Lr35 (70%), followed by Lr22 (60%), Lr27 (40%), Lr34 (30%), Lr19 (30%),Lr18 (10%),Lr36 (10%) and Lr46 (10%), eight out of sixteen Lr genes were not present in the tested cultivars. It is concluded that there was a good variation in Lr genes carried by wheat cultivars commercially grown in Egypt. Therefore, strategies for deploying resistance genes to prolong effective disease resistance are suggested to control wheat leaf rust disease.

scholarly journals Leaf Rust on Aegilops speltoides Caused by a New Forma Specialis of Puccinia triticina

2004 ◽  
Vol 94 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Pnina Ben Yehuda ◽  
Tamar Eilam ◽  
Jacob Manisterski ◽  
Ayelet Shimoni ◽  
Yehoshua Anikster
Keyword(s):  
Leaf Rust ◽  
Host Preference ◽  
Natural Habitat ◽  
Puccinia Triticina ◽  
Aegilops Speltoides ◽  
Wheat Cultivars ◽  
Wheat Leaf Rust ◽  
Forma Specialis ◽  
Wheat Leaf ◽  
First Time

A leaf rust attacking Aegilops speltoides in its natural habitat is reported for the first time. It was found in two locations in northern and central Israel. The two collections from A. speltoides resemble wheat leaf rust, Puccinia triticina, in most spore dimensions, in the morphology of the substomatal vesicle of the urediniospore, and in DNA content in pycniospore nuclei. Similarly to P. triticina isolates from wheat, isolates taken from A. speltoides are compatible with Thalictrum speciosissimum as an aecial host and they are crossed easily with wheat leaf rust isolates. However, isolates from A. speltoides differ from wheat leaf rust in their telial host range. They are avirulent to cultivated wheat cultivars, but attack hundreds of A. speltoides accessions that were immune to wheat leaf rust. This distinct host preference justifies delineation of the newly found leaf rust as a forma specialis (f. sp. speltoides) within P. triticina.

scholarly journals Physiologic Specialization of Puccinia triticina on Wheat in the United States in 2003

Plant Disease ◽  
2005 ◽  
Vol 89 (11) ◽  
pp. 1201-1206 ◽  
Author(s):  
J. A. Kolmer ◽  
D. L. Long ◽  
M. E. Hughes
Keyword(s):  
United States ◽  
Leaf Rust ◽  
Great Plains ◽  
Puccinia Triticina ◽  
The United States ◽  
Wheat Cultivars ◽  
Ohio Valley ◽  
Virulence Phenotype ◽  
Common Phenotype ◽  
Wheat Leaf

Collections of Puccinia triticina were obtained from rust infected wheat leaves by cooperators throughout the United States and from surveys of wheat fields and nurseries in the Great Plains, Ohio Valley, Southeast, California, and the Pacific Northwest, in order to determine the virulence of the wheat leaf rust fungus in 2003. Single uredinial isolates (580 in total) were derived from the wheat leaf rust collections and tested for virulence phenotype on lines of Thatcher wheat that are near-isogenic for leaf rust resistance genes Lr1, Lr2a, Lr2c, Lr3, Lr9, Lr16, Lr24, Lr26, Lr3ka, Lr11, Lr17, Lr30, LrB, Lr10, Lr14a, and Lr18. In the United States in 2003, 52 virulence phenotypes of P. triticina were found. Virulence phenotype MBDS, which has been selected by virulence to resistance gene Lr17, was the most common phenotype in the United States. MBDS was found in the Southeast, Great Plains, the Ohio Valley, and California. Virulence phenotype THBJ, which has been selected by virulence to genes Lr16 and Lr26, was the second most common phenotype, and was found in the southern and northern central Great Plains region. Phenotype MCDS, which has been selected by virulence to genes Lr17 and Lr26, was the third most common phenotype and occurred in the same regions as MBDS. The use of wheat cultivars with leaf rust seedling resistance genes has selected leaf rust phenotypes with virulence to genes Lr9, Lr16, Lr17, Lr24, and Lr26. The population of P. triticina in the United States is highly diverse for virulence phenotypes, which will continue to present a challenge for the development of wheat cultivars with effective durable resistance.

scholarly journals Wheat leaf rust (Puccinia triticina Eriks.) virulence frequency and detection of resistance genes in wheat cultivars registered in the Czech Republic in 2016–2018

2020 ◽  
Vol 56 (No. 3) ◽  
pp. 87-92 ◽  
Author(s):  
Alena Hanzalová ◽  
Veronika Dumalasová ◽  
Ondřej Zelba
Keyword(s):  
Molecular Markers ◽  
Leaf Rust ◽  
Puccinia Triticina ◽  
Near Isogenic Lines ◽  
Wheat Cultivars ◽  
Wheat Leaf Rust ◽  
The Czech Republic ◽  
Lr Genes ◽  
Wheat Leaf ◽  
Virulence Frequency

In 2016–2018 virulence of the Czech wheat leaf rust population was studied on Thatcher near-isogenic lines, carrying different Lr genes, and 130 leaf rust isolates. Virulence to Lr9 was found only sporadically. Virulence frequency to Lr2a, Lr2b, Lr2c and Lr28 was lower than in previous years. All tested isolates were avirulent to Lr19. Lr24 conditioned resistance to majority of isolates. Nineteen recently registered Czech cultivars were tested with six isolates of the pathogen and Lr genes were postulated. Presence of genes Lr1, Lr10, Lr19, Lr24, Lr26, Lr28, Lr34 and Lr37 was tested by molecular markers. Lr37 prevailed, followed by Lr genes 10, 24, 28, 1 and 26; genes Lr19 and Lr34 were not determined.

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