leaf rust resistance
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2022 ◽  
Vol 12 ◽  
Author(s):  
Firdissa E. Bokore ◽  
Ron E. Knox ◽  
Colin W. Hiebert ◽  
Richard D. Cuthbert ◽  
Ron M. DePauw ◽  
...  

The hexaploid spring wheat cultivar, Carberry, was registered in Canada in 2009, and has since been grown over an extensive area on the Canadian Prairies. Carberry has maintained a very high level of leaf rust (Puccinia triticina Eriks.) resistance since its release. To understand the genetic basis of Carberry’s leaf rust resistance, Carberry was crossed with the susceptible cultivar, Thatcher, and a doubled haploid (DH) population of 297 lines was generated. The DH population was evaluated for leaf rust in seven field environments at the adult plant stage. Seedling and adult plant resistance (APR) to multiple virulence phenotypes of P. triticina was evaluated on the parents and the progeny population in controlled greenhouse studies. The population was genotyped with the wheat 90 K iSelect single nucleotide polymorphism (SNP) array, and quantitative trait loci (QTL) analysis was performed. The analysis using field leaf rust response indicated that Carberry contributed nine QTL located on chromosomes 1B, 2B (2 loci), 2D, 4A, 4B, 5A, 5B, and 7D. The QTL located on 1B, 2B, 5B, and 7D chromosomes were observed in two or more environments, whereas the remainder were detected in single environments. The resistance on 1B, detected in five environments, was attributed to Lr46 and on 7D, detected in seven environments to Lr34. The first 2B QTL corresponded with the adult plant gene, Lr13, while the second QTL corresponded with Lr16. The seedling analysis showed that Carberry carries Lr2a, Lr16, and Lr23. Five epistatic effects were identified in the population, with synergistic interactions being observed for Lr34 with Lr46, Lr16, and Lr2a. The durable rust resistance of Carberry is attributed to Lr34 and Lr46 in combination with these other resistance genes, because the resistance has remained effective even though the P. triticina population has evolved virulent to Lr2a, Lr13, Lr16, and Lr23.


2021 ◽  
pp. 15-20
Author(s):  
N. N. Vozhzhova ◽  
О. S. Zhogaleva ◽  
А. Yu. Dubina ◽  
N. T. Kupreyshvili ◽  
T. G. Derova ◽  
...  

Nowadays in Russia and in the world, the problem of improving food security is becoming more and more urgent. One of the main crops grown worldwide is winter bread wheat. Varieties resistant to main leaf diseases can produce large grain yields. Thus, the study and identification of resistance genes are of great importance. The purpose of the current work was to estimate the gene pool of winter bread wheat from the CIMMYT collection (Mexico) according to the age brown rust Lr 34 resistance gene. In the study of collection samples, there have been used such methods as DNA extraction using CTAB, PCR, electrophoresis on agarose gels. As a result of the study, there has been identified a presence of a functional allele of the Lr 34 gene in 146 winter bread wheat samples out of 411 studied ones (sets 20th IWWYT-SA, 21th IWWYT-IRR, 25th FAWWON-IRR, 25th FAWWON-SA). There have been identified three samples with a heterozygous allelic state of the Lr 34 gene. There have been identified 232 samples with the non-functional Lr 34 gene allele. 30 winter bread wheat samples had no amplification of DNA fragments with the molecular marker csLV34, which means a significant microsatellite sequence variability for which the molecular marker was developed in their genotype. 121 out of 146 winter bread wheat samples with the functional brown rust Lr 34 resistance gene showed resistance in field conditions and in the infectious plots. The rest 25 samples with the Lr 34 gene belonged to the group of moderately resistant ones in the infectious plots. The identified 121 CIMMYT collection winter bread wheat varieties, with the Lr 34 gene possessing a resistant type of pathogen damage response (for example, 9919, 9921, 9928, 9809, 9811, 9812, 23, 24, 30, 262, 265, 266, etc.) have been recommended for use in leaf rust resistance pyramiding in future breeding programs.


2021 ◽  
Vol 25 (7) ◽  
pp. 770-777
Author(s):  
R. O. Davoyan ◽  
I. V. Bebyakina ◽  
E. R. Davoyan ◽  
Y. S. Zubanova ◽  
D. M. Boldakov ◽  
...  

The use of the gene pool of wild relatives, which have a significant reserve of genetic diversity, is of immediate interest for breeding common wheat. The creation and use of synthetic forms as “bridges” is an effective method of transferring valuable genetic material from wild relatives to cultivated wheat. For this purpose, genome addition, genome substitution and recombinant “secondary” synthetic forms have been created in the P.P. Lukyanenko National Center of Grain. The synthetic recombination form RS5 (BBAASDt ), in which the third genome consists of chromosomes of Aegilops speltoides (S) and Aegilops tauschii (Dt ), was obtained from crossing the synthetic forms Avrodes (BBAASS) and M.it./Ae. tauschii (BBAADt Dt ), in which the D genome from Ae. tauschii was added to the BBAA genomes of the durum wheat cultivar Mutico italicum. Introgression lines resistant to leaf rust, yellow rust and powdery mildew have been obtained from backcrosses with the susceptible common wheat cultivars Krasnodarskaya 99, Rostislav and Zhirovka. Twelve resistant lines that additionally have high technological characteristics of grain and flour have been selected. The cytological study (С-banding) has revealed chromosomal modifications in 6 of 8 lines under study. The rearrangements mainly affected the chromosomes of the D genome, 1D, 3D, 4D, 6D and 7D. It was found that in most cases the genetic material from the synthetic form RS5 in the studied lines was represented by substituted chromosomes from Ae. tauschii. In line 5791p17, the substitution of chromosomes 6D from Ae. tauschii and 7D from Ae. speltoides was revealed. Substitutions 4D(4Dt ), 6D(6Dt ) from Ae. tauschii and 7D(7S) from Ae. speltoides were obtained for the first time. Molecular analysis of 12 lines did not reveal effective leaf rust resistance genes, presumably present in synthetic forms of M.it./Ae. tauschii and Avrodes. It is assumed that the lines may carry previously unidentified genes for fungal disease resistance, in particular for resistance to leaf rust, from Ae. tauschii and Ae. speltoides.


2021 ◽  
Author(s):  
Zahra Pourkhorshid ◽  
Ali Dadkhodaie ◽  
Roohollah Shamloo-Dashtpagerdi‎

Abstract Leaf rust is one of the most devastating wheat diseases worldwide, to which many resistance genes have been ‎successfully introgressed ‎from wheat wild relatives. Though the Thinopyrum ‎ponticum-derived leaf rust resistance gene Lr19, is widely effective worldwide and previous studies ‎have shown its likely presence in Aegilops tauschii, no ‎thorough investigation has been conducted to confirm this. The present study aimed to ‎examine the presence of Lr19 in Ae. tauschii using a collection of molecular and bioinformatic analysis. Accordingly, the Thatcher line was used as susceptible, and a Thatcher+Lr19 (TcLr19) and Agatha were used as resistant lines. CDHLQ pathotyping coupled with DNA markers genotyping verified the presence of an Lr19 orthologue on Ae. tauschii 7DL (AtLr19). Sequencing of the GB marker products from Ae. tauschii and TcLr19 showed 99% homology in these fragments, confirming phenotyping and genotyping results. Both isolated segments were matched to a putative melatonin biosynthesis gene, namely O-methyltransferase-2 (OMT2) mapped to 7DL, with 100% identity. A hierarchical gene network was reconstructed using all identified putative genes within a genomic region containing 2.5 cM upstream and downstream of the OMT2 gene. Results indicated that several numbers of important biotic stress-responsive genes such as RPM1, RGA2, TRIUR3, BURP12, and myosin-11, were located downstream of melatonin as a master regulator molecule through the OMT2 node. To our knowledge, this is the first report of finding an orthologue for ‎Lr19 in Ae. tauschii, which provides insights into the possible regulatory route of LR19.


2021 ◽  
Vol 845 (1) ◽  
pp. 012070
Author(s):  
Yu V Zeleneva ◽  
V P Sudnikova ◽  
V A Lavrinova ◽  
T S Polunina

Abstract To develop and optimize protective measures in the CCR conditions, an analysis of the epidemic resistance of zoned varieties and hybrid lines of spring wheat to the causative agents of septoria, brown and yellow rust was carried out; the effect of fungicides, biological agents, their binary mixtures was studied for wheat crops. Among the selection material of spring wheat, lines and numbers were identified and selected as potential genetic sources and donors, combining resistance to environmental stress factors (brown and yellow rust, septoria blight) with productivity and adaptability to the conditions of the Central Black Earth Region. Using DNA markers, Lr genes in the lines selected as potential donors of leaf rust resistance were identified. In the genotypes of selection lines, the Lr19 gene dominance was revealed in combination with the weakly effective genes Lr10, Lr 20, and Lr 26. It was observed that the combination of Lr19 + Lr26 increases the level of resistance. All zoned varieties were affected by diseases, which indicates the need for protective measures. The biological effectiveness of chemical and biological agents against aerogenic diseases was established in the range of 82.1-100%. Amistar Extra was effective against septoria, perenophorosis and leaf rust, Rex Duo was effective against leaf rust, Title Duo was effective against powdery mildew. Amist Extra 0.7 l / ha + Biostim 2.0 l / ha was effective against leaf rust (99.4%) and powdery mildew (98.9%). A mixture of Amistar Extra 0.7 l / ha and Alfastim 30 ml / ha was effective against septoria (93.0%) and pyrenoforosis (100%). Mixed forms of Amistar Extra 0.7 l / ha + Alfastim 30 ml / ha (91.3-95.7%) and Amistar Extra 0.7 l / ha + Healthy yield 0.9 l / ha (91.0-95.7%) were effective against septoria spot and brown rust.


Author(s):  
E. I. Gultyaeva ◽  
E. L. Shaydayuk

Background. Wheat leaf rust caused by Puccinia triticina Erikss. is a significant wheat disease in all regions of the Russian Federation. The genetic diversity of the cultivated wheat varieties regarding the type of resistance and genes that control it ensures reliable protection of this crop against the pathogen. The aim of this work was to characterize the diversity of new Russian varieties of winter and spring common wheat for leaf rust resistance genes (Lr-genes).Materials and Methods. The research material was represented by 43 varieties of winter and 25 of spring wheat included in the State Register of Selection Achievements of the Russian Federation in 2018-2020.Results. Using molecular markers, 18 Lr genes were identified: Lr1, Lr3, Lr9, Lr10, Lr19, Lr20, Lr21, Lr24, Lr25, Lr26, Lr28, Lr29, Lr34, Lr35, Lr37, Lr41 (39), Lr47 and Lr66. A phytopathological test was used to clarify the results of molecular analysis. Ninety-three percent of the studied wheat varieties were found to contain Lr genes, either separately or in combinations. These were the highly and partially effective genes Lr24, Lr9, and Lr19, adult plant resistance genes Lr34 and Lr37, and ineffective genes Lr1, Lr3, Lr10, Lr20, and Lr26. The Lr24 gene has been identified for the first time in Russian varieties. The spring variety ‘Leader 80’, harboring this gene, is recommended for cultivation in the West Siberian and East Siberian regions. An effective combination of Lr9 + Lr26 genes, individually overcome by the pathogen, was determined in the spring cultivar ‘Silach’, highly resistant to leaf rust. The Lr9 gene was found in the winter variety ‘Gerda’, which is recommended for cultivation in the North Caucasus region. Previously, the varieties with Lr9 were not grown in the North Caucasus. An increase in the number of leaf rust resistant accessions protected by the effective adult plant resistance gene Lr37 is noted among wheat varieties undergoing regional adaptation testing. Many of the identified Lr genes (Lr19, Lr24, Lr26, Lr34, Lr37) are linked with effective Sr genes (Sr25, Sr24, Sr31, Sr57, and Sr38), which additionally ensures stable genetic protection of wheat against stem rust.Conclusions. The obtained information about representation of Lr genes in wheat varieties should be used in regional breeding programs. A timely replacement of genetically protected varieties allows stabilizing the populational composition of the phytopathogen and reducing the likelihood of epiphytotics.


Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1484
Author(s):  
Alma Kokhmetova ◽  
Shynbolat Rsaliyev ◽  
Makpal Atishova ◽  
Madina Kumarbayeva ◽  
Angelina Malysheva ◽  
...  

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.


2021 ◽  
Author(s):  
James Kolmer ◽  
Adam Herman ◽  
John Fellers

Wheat leaf rust caused by Puccinia triticina, is a widespread disease of wheat in the United States and worldwide. Populations of P. triticina are characterized by virulence phenotypes that change rapidly due to selection by wheat cultivars with leaf rust resistance genes. The objective of this study was to genotype collections of P. triticina from 2011-2018 in the United States, using restriction site associated genotyping by sequencing (GBS), to determine if recently identified new virulence phenotypes belong to established genotype groups or belong to groups previously not detected. A total of 158 isolates were phenotyped for virulence on 20 lines of Thatcher wheat that are isogenic for leaf rust resistance genes and were also genotyped for single nucleotide polymorphism. Eight distinct groups of P. triticina genotypes from common wheat were described based on coancestry, nucleotide divergence, and principal coordinate plots. A separate genotype group had isolates with virulence to durum wheat. Isolates within groups had similar virulence phenotype, and the overall population had high level of heterozygosity and a high level of linkage disequilibria, which were all indicators of clonality. Two new genotype groups were described, raising the possibility of new introductions of P. triticina, although genotypes in these groups may have also originated from somatic nuclear exchange and recombination. A genome wide association study detected 19 SNPs that were highly associated with virulence to 11 resistance genes in the Thatcher near isogenic lines.


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