Nonhost resistance to rust pathogens – a continuation of continua

Directory of Open Access Journals (Sweden)

Jan eBettgenhaeuser

2014-12-01

Full Text Available The rust fungi (order: Pucciniales are a group of widely distributed fungal plant pathogens, which can infect representatives of all vascular plant groups. Rust diseases significantly impact several crop species and considerable research focuses on understanding the basis of host specificity and nonhost resistance. Like many pathogens, rust fungi vary considerably in the number of hosts they can infect, such as wheat leaf rust (Puccinia triticina, which can only infect species in the genera Triticum and Aegilops, whereas Asian soybean rust (Phakopsora pachyrhizi is known to infect over 95 species from over 42 genera. A greater understanding of the genetic basis determining host range has the potential to identify sources of durable resistance for agronomically important crops. Delimiting the boundary between host and nonhost has been complicated by the quantitative nature of phenotypes in the transition between these two states. Plant-pathogen interactions in this intermediate state are characterized either by (1 the majority of accessions of a species being resistant to the rust or (2 the rust only being able to partially complete key components of its life cycle. This leads to a continuum of disease phenotypes in the interaction with different plant species, observed as a range from compatibility (host to complete immunity within a species (nonhost. In this review we will highlight how the quantitative nature of disease resistance in these intermediate interactions is caused by a continuum of defense barriers, which a pathogen needs to overcome for successfully establishing itself in the host. To illustrate continua as this underlying principle, we will discuss the advances that have been made in studying nonhost resistance towards rust pathogens, particularly cereal rust pathogens.

Nonhost resistance to rust pathogens – a continuation of continua

Science.gov (United States)

Bettgenhaeuser, Jan; Gilbert, Brian; Ayliffe, Michael; Moscou, Matthew J.

2014-01-01

The rust fungi (order: Pucciniales) are a group of widely distributed fungal plant pathogens, which can infect representatives of all vascular plant groups. Rust diseases significantly impact several crop species and considerable research focuses on understanding the basis of host specificity and nonhost resistance. Like many pathogens, rust fungi vary considerably in the number of hosts they can infect, such as wheat leaf rust (Puccinia triticina), which can only infect species in the genera Triticum and Aegilops, whereas Asian soybean rust (Phakopsora pachyrhizi) is known to infect over 95 species from over 42 genera. A greater understanding of the genetic basis determining host range has the potential to identify sources of durable resistance for agronomically important crops. Delimiting the boundary between host and nonhost has been complicated by the quantitative nature of phenotypes in the transition between these two states. Plant–pathogen interactions in this intermediate state are characterized either by (1) the majority of accessions of a species being resistant to the rust or (2) the rust only being able to partially complete key components of its life cycle. This leads to a continuum of disease phenotypes in the interaction with different plant species, observed as a range from compatibility (host) to complete immunity within a species (nonhost). In this review we will highlight how the quantitative nature of disease resistance in these intermediate interactions is caused by a continuum of defense barriers, which a pathogen needs to overcome for successfully establishing itself in the host. To illustrate continua as this underlying principle, we will discuss the advances that have been made in studying nonhost resistance towards rust pathogens, particularly cereal rust pathogens. PMID:25566270

Duplications and losses in gene families of rust pathogens highlight putative effectors.

Science.gov (United States)

Pendleton, Amanda L; Smith, Katherine E; Feau, Nicolas; Martin, Francis M; Grigoriev, Igor V; Hamelin, Richard; Nelson, C Dana; Burleigh, J Gordon; Davis, John M

2014-01-01

Rust fungi are a group of fungal pathogens that cause some of the world's most destructive diseases of trees and crops. A shared characteristic among rust fungi is obligate biotrophy, the inability to complete a lifecycle without a host. This dependence on a host species likely affects patterns of gene expansion, contraction, and innovation within rust pathogen genomes. The establishment of disease by biotrophic pathogens is reliant upon effector proteins that are encoded in the fungal genome and secreted from the pathogen into the host's cell apoplast or within the cells. This study uses a comparative genomic approach to elucidate putative effectors and determine their evolutionary histories. We used OrthoMCL to identify nearly 20,000 gene families in proteomes of 16 diverse fungal species, which include 15 basidiomycetes and one ascomycete. We inferred patterns of duplication and loss for each gene family and identified families with distinctive patterns of expansion/contraction associated with the evolution of rust fungal genomes. To recognize potential contributors for the unique features of rust pathogens, we identified families harboring secreted proteins that: (i) arose or expanded in rust pathogens relative to other fungi, or (ii) contracted or were lost in rust fungal genomes. While the origin of rust fungi appears to be associated with considerable gene loss, there are many gene duplications associated with each sampled rust fungal genome. We also highlight two putative effector gene families that have expanded in Cqf that we hypothesize have roles in pathogenicity.

A new 2DS·2RL Robertsonian translocation transfers stem rust resistance gene Sr59 into wheat.

Science.gov (United States)

Rahmatov, Mahbubjon; Rouse, Matthew N; Nirmala, Jayaveeramuthu; Danilova, Tatiana; Friebe, Bernd; Steffenson, Brian J; Johansson, Eva

2016-07-01

A new stem rust resistance gene Sr59 from Secale cereale was introgressed into wheat as a 2DS·2RL Robertsonian translocation. Emerging new races of the wheat stem rust pathogen (Puccinia graminis f. sp. tritici), from Africa threaten global wheat (Triticum aestivum L.) production. To broaden the resistance spectrum of wheat to these widely virulent African races, additional resistance genes must be identified from all possible gene pools. From the screening of a collection of wheat-rye (Secale cereale L.) chromosome substitution lines developed at the Swedish University of Agricultural Sciences, we described the line 'SLU238' 2R (2D) as possessing resistance to many races of P. graminis f. sp. tritici, including the widely virulent race TTKSK (isolate synonym Ug99) from Africa. The breakage-fusion mechanism of univalent chromosomes was used to produce a new Robertsonian translocation: T2DS·2RL. Molecular marker analysis and stem rust seedling assays at multiple generations confirmed that the stem rust resistance from 'SLU238' is present on the rye chromosome arm 2RL. Line TA5094 (#101) was derived from 'SLU238' and was found to be homozygous for the T2DS·2RL translocation. The stem rust resistance gene on chromosome 2RL arm was designated as Sr59. Although introgressions of rye chromosome arms into wheat have most often been facilitated by irradiation, this study highlights the utility of the breakage-fusion mechanism for rye chromatin introgression. Sr59 provides an additional asset for wheat improvement to mitigate yield losses caused by stem rust.

Attempts to induce mutations for resistance of wheat to mildew, stem rust and leaf rust

International Nuclear Information System (INIS)

Kiraly, Z.; Barabas, Z.

1983-01-01

Research carried out between 1971 and 1981 is summarized. Attempts to find induced mutants with full resistance to pathotype mixtures of the three pathogens were not successful. Reasons are discussed. Studies on wheat lines tolerant to stem rust infection led to the conclusion that this disease reaction may be often accompanied by a reduced number of infection sites and a longer lag period resulting in reduced spore production. Various selection methods have been evaluated. Selecting for the multigenic 'non race specific' way is promising. (author)

Duplications and losses in gene families of rust pathogens highlight putative effectors

Directory of Open Access Journals (Sweden)

Amanda L. Pendleton

2014-06-01

Full Text Available Rust fungi are a group of fungal pathogens that cause some of the world’s most destructive diseases of trees and crops. A shared characteristic among rust fungi is obligate biotrophy, the inability to complete a lifecycle without a host. This dependence on a host species likely affects patterns of gene expansion, contraction, and innovation within rust pathogen genomes. The establishment of disease by biotrophic pathogens is reliant upon effector proteins that are encoded in the fungal genome and secreted from the pathogen into the host’s cell apoplast or within the cells. This study uses a comparative genomic approach to elucidate putative effectors and determine their evolutionary histories. We used OrthoMCL to identify nearly 20,000 gene families in proteomes of sixteen diverse fungal species, which include fifteen basidiomycetes and one ascomycete. We inferred patterns of duplication and loss for each gene family and identified families with distinctive patterns of expansion/contraction associated with the evolution of rust fungal genomes. To recognize potential contributors for the unique features of rust pathogens, we identified families harboring secreted proteins that: i arose or expanded in rust pathogens relative to other fungi, or ii contracted or were lost in rust fungal genomes. While the origin of rust fungi appears to be associated with considerable gene loss, there are many gene duplications associated with each sampled rust fungal genome. We also highlight two putative effector gene families that have expanded in Cqf that we hypothesize have roles in pathogenicity.

Inheritance and Bulked Segregant Analysis of Leaf Rust and Stem Rust Resistance in Durum Wheat Genotypes.

Science.gov (United States)

Aoun, Meriem; Kolmer, James A; Rouse, Matthew N; Chao, Shiaoman; Bulbula, Worku Denbel; Elias, Elias M; Acevedo, Maricelis

2017-12-01

Leaf rust, caused by Puccinia triticina, and stem rust, caused by P. graminis f. sp. tritici, are important diseases of durum wheat. This study determined the inheritance and genomic locations of leaf rust resistance (Lr) genes to P. triticina race BBBQJ and stem rust resistance (Sr) genes to P. graminis f. sp. tritici race TTKSK in durum accessions. Eight leaf-rust-resistant genotypes were used to develop biparental populations. Accessions PI 192051 and PI 534304 were also resistant to P. graminis f. sp. tritici race TTKSK. The resulting progenies were phenotyped for leaf rust and stem rust response at seedling stage. The Lr and Sr genes were mapped in five populations using single-nucleotide polymorphisms and bulked segregant analysis. Five leaf-rust-resistant genotypes carried single dominant Lr genes whereas, in the remaining accessions, there was deviation from the expected segregation ratio of a single dominant Lr gene. Seven genotypes carried Lr genes different from those previously characterized in durum. The single dominant Lr genes in PI 209274, PI 244061, PI387263, and PI 313096 were mapped to chromosome arms 6BS, 2BS, 6BL, and 6BS, respectively. The Sr gene in PI 534304 mapped to 6AL and is most likely Sr13, while the Sr gene in PI 192051 could be uncharacterized in durum.

Stripe rust and leaf rust resistance QTL mapping, epistatic interactions, and co-localization with stem rust resistance loci in spring wheat evaluated over three continents.

Science.gov (United States)

Singh, A; Knox, R E; DePauw, R M; Singh, A K; Cuthbert, R D; Campbell, H L; Shorter, S; Bhavani, S

2014-11-01

In wheat, advantageous gene-rich or pleiotropic regions for stripe, leaf, and stem rust and epistatic interactions between rust resistance loci should be accounted for in plant breeding strategies. Leaf rust (Puccinia triticina Eriks.) and stripe rust (Puccinia striiformis f. tritici Eriks) contribute to major production losses in many regions worldwide. The objectives of this research were to identify and study epistatic interactions of quantitative trait loci (QTL) for stripe and leaf rust resistance in a doubled haploid (DH) population derived from the cross of Canadian wheat cultivars, AC Cadillac and Carberry. The relationship of leaf and stripe rust resistance QTL that co-located with stem rust resistance QTL previously mapped in this population was also investigated. The Carberry/AC Cadillac population was genotyped with DArT(®) and simple sequence repeat markers. The parents and population were phenotyped for stripe rust severity and infection response in field rust nurseries in Kenya (Njoro), Canada (Swift Current), and New Zealand (Lincoln); and for leaf rust severity and infection response in field nurseries in Canada (Swift Current) and New Zealand (Lincoln). AC Cadillac was a source of stripe rust resistance QTL on chromosomes 2A, 2B, 3A, 3B, 5B, and 7B; and Carberry was a source of resistance on chromosomes 2B, 4B, and 7A. AC Cadillac contributed QTL for resistance to leaf rust on chromosome 2A and Carberry contributed QTL on chromosomes 2B and 4B. Stripe rust resistance QTL co-localized with previously reported stem rust resistance QTL on 2B, 3B, and 7B, while leaf rust resistance QTL co-localized with 4B stem rust resistance QTL. Several epistatic interactions were identified both for stripe and leaf rust resistance QTL. We have identified useful combinations of genetic loci with main and epistatic effects. Multiple disease resistance regions identified on chromosomes 2A, 2B, 3B, 4B, 5B, and 7B are prime candidates for further investigation and

stem rust seedling resistance genes in ethiopian wheat cultivars

African Journals Online (AJOL)

Prof. Adipala Ekwamu

Stem rust caused by Puccinia graminis f. sp. tritici is one of the major biotic limiting factors for wheat production in Ethiopia. Host plant resistance is the best option to manage stem rust from its economic and environmental points of view. Wheat cultivars are released for production without carrying race specific tests against ...

Genetic characterization of stem rust resistance in a global spring wheat germplasm collection

Science.gov (United States)

Stem rust is considered one of the most damaging diseases of wheat. The recent emergence of the stem rust Ug99 race group poses a serious threat to world wheat production. Utilization of genetic resistance in cultivar development is the optimal way to control stem rust. Here we report association ma...

Somatic recombination in wheat stem rust leads to virulence for Ug99-effective SR50 resistance

Science.gov (United States)

Race-specific resistance genes protect much of the global wheat crop from stem rust disease caused by Puccinia graminis f. sp. tritici (Pgt), but often break down due to evolution of new virulent pathogen races. To understand the molecular mechanisms of virulence evolution in Pgt we identified the p...

Wheat stem rust in South Africa: Current status and future research ...

African Journals Online (AJOL)

. In South Africa, stem rust caused by Puccinia graminis Pers. f. sp. tritici. Eriks. & E. Henn. (Pgt) is an important disease of wheat. Records of stem rust occurrence in South Africa date back to the late 1720's, when it was first discovered in the ...

75 FR 44881 - Black Stem Rust; Additions of Rust-Resistant Varieties

Science.gov (United States)

2010-07-30

...;Prices of new books are listed in the first FEDERAL REGISTER issue of each #0;week. #0; #0; #0; #0;#0... direct final rule notified the public of our intention to amend the black stem rust quarantine and...

76 FR 3011 - Black Stem Rust; Additions of Rust-Resistant Varieties

Science.gov (United States)

2011-01-19

...;Prices of new books are listed in the first FEDERAL REGISTER issue of each #0;week. #0; #0; #0; #0;#0... notified the public of our intention to amend the black stem rust quarantine and regulations by adding four...

Using hierarchical clustering of secreted protein families to classify and rank candidate effectors of rust fungi

Science.gov (United States)

Rust fungi are obligate biotrophic pathogens causing considerable damage on crop plants. P. graminis f. sp. tritici, the causal agent of wheat stem rust, and M. larici-populina, the poplar rust pathogen, have strong deleterious impact on wheat and poplar wood production, respectively. The recently r...

Detection of wheat stem rust race RRTTF in Ecuador in 2016

Science.gov (United States)

Wheat stem rust is a devastating disease that has incited numerous severe epidemics resulting in extreme yield losses over the past century. Stem rust infection in plots of wheat line UC11075, known to carry the Sr38 resistance gene, was severe in February 2016 in a nursery at the Instituto Nacional...

Studies of the genetics of inheritance of stem rust resistance in ...

African Journals Online (AJOL)

Five resistant wheat lines (KSL-2, KSL-3, KSL-5, KSL-12 and KSL-19) which were resistant in tests during 2008, 2009 and 2010 were used as parents in crosses with stem rust susceptible line CACUKE to develop genetic populations for determining the inheritance of resistance to stem rust. F3 populations were evaluated ...

Genomic analysis of a novel gene conferring resistance to Ug99 stem rust in Triticum turgidum ssp. dicoccum

Science.gov (United States)

Wheat production is threatened by the disease stem rust, which is caused by the biotrophic fungal pathogen Puccinia graminis Pers.:Pers. f. sp. tritici (Pgt). Among all known Pgt races, TTKSK (Ug99) and TRTTF are significant threats to North American wheat production due to their virulence against f...

Diversifying Selection in the Wheat Stem Rust Fungus Acts Predominantly on Pathogen-Associated Gene Families and Reveals Candidate Effectors

Directory of Open Access Journals (Sweden)

Jana eSperschneider

2014-09-01

Full Text Available Plant pathogens cause severe losses to crop plants and threaten global food production. One striking example is the wheat stem rust fungus, Puccinia graminis f. sp. tritici, which can rapidly evolve new virulent pathotypes in response to resistant host lines. Like several other filamentous fungal and oomycete plant pathogens, its genome features expanded gene families that have been implicated in host-pathogen interactions, possibly encoding effector proteins that interact directly with target host defence proteins. Previous efforts to understand virulence largely relied on the prediction of secreted, small and cysteine-rich proteins as candidate effectors and thus delivered an overwhelming number of candidates. Here, we implement an alternative analysis strategy that uses the signal of adaptive evolution as a line of evidence for effector function, combined with comparative information and expression data. We demonstrate that in planta up-regulated genes that are rapidly evolving are found almost exclusively in pathogen-associated gene families, affirming the impact of host-pathogen co-evolution on genome structure and the adaptive diversification of specialised gene families. In particular, we predict 42 effector candidates that are conserved only across pathogens, induced during infection and rapidly evolving. One of our top candidates has recently been shown to induce genotype-specific hypersensitive cell death in wheat. This shows that comparative genomics incorporating the evolutionary signal of adaptation is powerful for predicting effector candidates for laboratory verification. Our system can be applied to a wide range of pathogens and will give insight into host-pathogen dynamics, ultimately leading to progress in strategies for disease control.

Protection of wheat against leaf and stem rust and powdery mildew diseases by inhibition of polyamine metabolism

Science.gov (United States)

Weinstein, L. H.; Osmeloski, J. F.; Wettlaufer, S. H.; Galston, A. W.

1987-01-01

In higher plants, polyamines arise from arginine by one of two pathways: via ornithine and ornithine decarboxylase or via agmatine and arginine decarboxylase but in fungi, only the ornithine decarboxylase pathway is present. Since polyamines are required for normal growth of microorganisms and plants and since the ornithine pathway can be irreversibly blocked by alpha-difluoromethylornithine (DFMO) which has no effect on arginine decarboxylase, fungal infection of green plants might be controlled by the site-directed use of such a specific metabolic inhibitor. DFMO at relatively low concentrations provided effective control of the three biotrophic fungal pathogens studied, Puccinia recondita (leaf rust), P. graminis f. sp. tritici (stem rust), and Erysiphe graminis (powdery mildew) on wheat (Triticum aestivum L.) Effective control of infection by leaf or stem rust fungi was obtained with sprays of DFMO that ranged from about 0.01 to 0.20 mM in experiments where the inhibitor was applied after spore inoculation. The powdery mildew fungus was somewhat more tolerant of DFMO, but good control of the pathogen was obtained at less than 1.0 mM. In general, application of DFMO after spore inoculation was more effective than application before inoculation. Less control was obtained following treatment with alpha-difluoromethylarginine (DFMA) but the relatively high degree of control obtained raises the possibility of a DFMA to DFMO conversion by arginase.

Effect of fungicide on the development of wheat stem rust and yield ...

African Journals Online (AJOL)

Stem rust caused by Puccinia graminis f.sp tritici Erik. & E. Henn. is a highly destructive disease of wheat (Triticum aestivum L.). The effects of fungicide application on stem rust (Puccinia graminis tritici) epidemics and yield of three bread wheat varieties varying in reaction to the disease were studied in two major wheat ...

Genetic characterisation of novel resistance alleles to stem rust and stripe rust in wheat-alien introgression lines

OpenAIRE

Rahmatov, Mahbubjon

2016-01-01

Bread wheat (Triticum aestivum L., 2n = 6x = 42, AABBDD) is one of the most important food crops world-wide, but is attacked by many diseases and pests that cause significant yield losses. Globally, stem rust (Sr) (Puccinia graminis f. sp. tritici Erikss & E. Henning), stripe rust (Yr) (Puccinia striiformis Westend. f. sp. tritici Eriks) and leaf rust (Lr) (Puccinia triticina Eriks) are a great threat to wheat production. The majority of the Sr, Yr and Lr resistance genes are already defeated...

Mapping resistance to the Ug99 race group of the stem rust pathogen in a spring wheat landrace.

Science.gov (United States)

Babiker, E M; Gordon, T C; Chao, S; Newcomb, M; Rouse, M N; Jin, Y; Wanyera, R; Acevedo, M; Brown-Guedira, G; Williamson, S; Bonman, J M

2015-04-01

A new gene for Ug99 resistance from wheat landrace PI 374670 was detected on the long arm of chromosome 7A. Wheat landrace PI 374670 has seedling and field resistance to stem rust caused by Puccinia graminis f. sp tritici Eriks. & E. Henn (Pgt) race TTKSK. To elucidate the inheritance of resistance, 216 BC1F2 families, 192 double haploid (DH) lines, and 185 recombinant inbred lines (RILs) were developed by crossing PI 374670 and the susceptible line LMPG-6. The parents and progeny were evaluated for seedling resistance to Pgt races TTKSK, MCCFC, and TPMKC. The DH lines were tested in field stem rust nurseries in Kenya and Ethiopia. The DH lines were genotyped with the 90K wheat iSelect SNP genotyping platform. Goodness-of-fit tests indicated that a single dominant gene in PI 374670 conditioned seedling resistance to the three Pgt races. The seedling resistance locus mapped to the long arm of chromosome 7A and this result was verified in the RIL population screened with the flanking SNP markers using KASP assays. In the same region, a major QTL for field resistance was detected in a 7.7 cM interval and explained 34-54 and 29-36% of the variation in Kenya and Ethiopia, respectively. Results from tests with specific Pgt races and the csIH81 marker showed that the resistance was not due to Sr22. Thus, a new stem rust resistance gene or allele, either closely linked or allelic to Sr15, is responsible for the seedling and field resistance of PI 374670 to Ug99.

Postulation of rust resistance genes in Nordic spring wheat genotypes and identification of widely effective sources of resistance against the Australian rust flora.

Science.gov (United States)

Randhawa, Mandeep; Bansal, Urmil; Lillemo, Morten; Miah, Hanif; Bariana, Harbans

2016-11-01

Wild relatives, landraces and cultivars from different geographical regions have been demonstrated as the sources of genetic variation for resistance to rust diseases. This study involved assessment of diversity for resistance to three rust diseases among a set of Nordic spring wheat cultivars. These cultivars were tested at the seedling stage against several pathotypes of three rust pathogens in the greenhouse. All stage stem rust resistance genes Sr7b, Sr8a, Sr12, Sr15, Sr17, Sr23 and Sr30, and leaf rust resistance genes Lr1, Lr3a, Lr13, Lr14a, Lr16 and Lr20 were postulated either singly or in different combinations among these cultivars. A high proportion of cultivars were identified to carry linked rust resistance genes Sr15 and Lr20. Although 51 cultivars showed variation against Puccinia striiformis f. sp. tritici (Pst) pathotypes used in this study, results were not clearly contrasting to enable postulation of stripe rust resistance genes in these genotypes. Stripe rust resistance gene Yr27 was postulated in four cultivars and Yr1 was present in cultivar Zebra. Cultivar Tjalve produced low stripe rust response against all Pst pathotypes indicating the presence either of a widely effective resistance gene or combination of genes with compensating pathogenic specificities. Several cultivars carried moderate to high level of APR to leaf rust and stripe rust. Seedling stem rust susceptible cultivar Aston exhibited moderately resistant to moderately susceptible response, whereas other cultivars belonging to this class were rated moderately susceptible or higher. Molecular markers linked with APR genes Yr48, Lr34/Yr18/Sr57, Lr68 and Sr2 detected the presence of these genes in some genotypes.

Emergence and Spread of New Races of Wheat Stem Rust Fungus: Continued Threat to Food Security and Prospects of Genetic Control.

Science.gov (United States)

Singh, Ravi P; Hodson, David P; Jin, Yue; Lagudah, Evans S; Ayliffe, Michael A; Bhavani, Sridhar; Rouse, Matthew N; Pretorius, Zacharias A; Szabo, Les J; Huerta-Espino, Julio; Basnet, Bhoja R; Lan, Caixia; Hovmøller, Mogens S

2015-07-01

Race Ug99 (TTKSK) of Puccinia graminis f. sp. tritici, detected in Uganda in 1998, has been recognized as a serious threat to food security because it possesses combined virulence to a large number of resistance genes found in current widely grown wheat (Triticum aestivum) varieties and germplasm, leading to its potential for rapid spread and evolution. Since its initial detection, variants of the Ug99 lineage of stem rust have been discovered in Eastern and Southern African countries, Yemen, Iran, and Egypt. To date, eight races belonging to the Ug99 lineage are known. Increased pathogen monitoring activities have led to the identification of other races in Africa and Asia with additional virulence to commercially important resistance genes. This has led to localized but severe stem rust epidemics becoming common once again in East Africa due to the breakdown of race-specific resistance gene SrTmp, which was deployed recently in the 'Digalu' and 'Robin' varieties in Ethiopia and Kenya, respectively. Enhanced research in the last decade under the umbrella of the Borlaug Global Rust Initiative has identified various race-specific resistance genes that can be utilized, preferably in combinations, to develop resistant varieties. Research and development of improved wheat germplasm with complex adult plant resistance (APR) based on multiple slow-rusting genes has also progressed. Once only the Sr2 gene was known to confer slow rusting APR; now, four more genes-Sr55, Sr56, Sr57, and Sr58-have been characterized and additional quantitative trait loci identified. Cloning of some rust resistance genes opens new perspectives on rust control in the future through the development of multiple resistance gene cassettes. However, at present, disease-surveillance-based chemical control, large-scale deployment of new varieties with multiple race-specific genes or adequate levels of APR, and reducing the cultivation of susceptible varieties in rust hot-spot areas remains the best

Studies on general resistance to stem rust in wheat

International Nuclear Information System (INIS)

Knott, D.R.

1977-01-01

Eight cultivars that were thought to have field resistance to stem rust were selected and crossed to produce four four-cultivar hybrids. From those crosses lines were produced that lacked seedling resistance to race 15B-1 of stem rust but had good field resistance to it. They also proved to have field resistance to many other races and it is hoped that the resistance is general. Genetic studies indicated that there is some variation in the lines, but resistance is generally inherited as a quantitative character with several largely recessive genes having small additive effects. This suggests that in an induced mutation programme, no one plant is likely to accumulate sufficient mutant genes that it will appear resistant. (author)

Identification of New Resistance Loci to African Stem Rust Race TTKSK in Tetraploid Wheats Based on Linkage and Genome-Wide Association Mapping.

Science.gov (United States)

Laidò, Giovanni; Panio, Giosuè; Marone, Daniela; Russo, Maria A; Ficco, Donatella B M; Giovanniello, Valentina; Cattivelli, Luigi; Steffenson, Brian; de Vita, Pasquale; Mastrangelo, Anna M

2015-01-01

Stem rust, caused by Puccinia graminis Pers. f. sp. tritici Eriks. and E. Henn. (Pgt), is one of the most destructive diseases of wheat. Races of the pathogen in the "Ug99 lineage" are of international concern due to their virulence for widely used stem rust resistance genes and their spread throughout Africa. Disease resistant cultivars provide one of the best means for controlling stem rust. To identify quantitative trait loci (QTL) conferring resistance to African stem rust race TTKSK at the seedling stage, we evaluated an association mapping (AM) panel consisting of 230 tetraploid wheat accessions under greenhouse conditions. A high level of phenotypic variation was observed in response to race TTKSK in the AM panel, allowing for genome-wide association mapping of resistance QTL in wild, landrace, and cultivated tetraploid wheats. Thirty-five resistance QTL were identified on all chromosomes, and seventeen are of particular interest as identified by multiple associations. Many of the identified resistance loci were coincident with previously identified rust resistance genes; however, nine on chromosomes 1AL, 2AL, 4AL, 5BL, and 7BS may be novel. To validate AM results, a biparental population of 146 recombinant inbred lines was also considered, which derived from a cross between the resistant cultivar "Cirillo" and susceptible "Neodur." The stem rust resistance of Cirillo was conferred by a single gene on the distal region of chromosome arm 6AL in an interval map coincident with the resistance gene Sr13, and confirmed one of the resistance loci identified by AM. A search for candidate resistance genes was carried out in the regions where QTL were identified, and many of them corresponded to NBS-LRR genes and protein kinases with LRR domains. The results obtained in the present study are of great interest as a high level of genetic variability for resistance to race TTKSK was described in a germplasm panel comprising most of the tetraploid wheat sub-species.

Wheat Ammonium Transporter (AMT) Gene Family: Diversity and Possible Role in Host-Pathogen Interaction with Stem Rust.

Science.gov (United States)

Li, Tianya; Liao, Kai; Xu, Xiaofeng; Gao, Yue; Wang, Ziyuan; Zhu, Xiaofeng; Jia, Baolei; Xuan, Yuanhu

2017-01-01

Ammonium transporter (AMT) proteins have been reported in many plants, but no comprehensive analysis was performed in wheat. In this study, we identified 23 AMT members (hereafter TaAMTs) using a protein homology search in wheat genome. Tissue-specific expression analysis showed that TaAMT1;1a, TaAMT1;1b , and TaAMT1;3a were relatively more highly expressed in comparison with other TaAMTs . TaAMT1;1a, TaAMT1;1b, and TaAMT1;3a-GFP were localized in the plasma membrane in tobacco leaves, and TaAMT1;1a, TaAMT1;1b , and TaAMT1;3a successfully complemented a yeast 31019b strain in which ammonium uptake was deficient. In addition, the expression of TaAMT1;1b in an Arabidopsis AMT quadruple mutant ( qko ) successfully restored [Formula: see text] uptake ability. Resupply of [Formula: see text] rapidly increased cellular [Formula: see text] contents and suppressed expression of TaAMT1;3a , but not of TaAMT;1;1a and TaAMT1;1b expressions. Expression of TaAMT1;1a, TaAMT1;1b , and TaAMT1;3a was not changed in leaves after [Formula: see text] resupply. In contrast, nitrogen (N) deprivation induced TaAMT1;1a, TaAMT1;1b , and TaAMT1;3a gene expressions in the roots and leaves. Expression analysis in the leaves of the stem rust-susceptible wheat line "Little Club" and the rust-tolerant strain "Mini 2761" revealed that TaAMT1;1a, TaAMT1;1b , and TaAMT1;3a were specifically induced in the former but not in the latter. Rust-susceptible wheat plants grown under N-free conditions exhibited a lower disease index than plants grown with [Formula: see text] as the sole N source in the medium after infection with Puccinia graminis f. sp. tritici , suggesting that [Formula: see text] and its transport may facilitate the infection of wheat stem rust disease. Our findings may be important for understanding the potential function TaAMTs in wheat plants.

Major Gene for Field Stem Rust Resistance Co-Locates with Resistance Gene Sr12 in 'Thatcher' Wheat.

Science.gov (United States)

Hiebert, Colin W; Kolmer, James A; McCartney, Curt A; Briggs, Jordan; Fetch, Tom; Bariana, Harbans; Choulet, Frederic; Rouse, Matthew N; Spielmeyer, Wolfgang

2016-01-01

Stem rust, caused by Puccinia graminis (Pgt), is a damaging disease of wheat that can be controlled by utilizing effective stem rust resistance genes. 'Thatcher' wheat carries complex resistance to stem rust that is enhanced in the presence of the resistance gene Lr34. The purpose of this study was to examine APR in 'Thatcher' and look for genetic interactions with Lr34. A RIL population was tested for stem rust resistance in field nurseries in Canada, USA, and Kenya. BSA was used to find SNP markers associated with reduced stem rust severity. A major QTL was identified on chromosome 3BL near the centromere in all environments. Seedling testing showed that Sr12 mapped to the same region as the QTL for APR. The SNP markers were physically mapped and the region carrying the resistance was searched for sequences with homology to members of the NB-LRR resistance gene family. SNP marker from one NB-LRR-like sequence, NB-LRR3 co-segregated with Sr12. Two additional populations, including one that lacked Lr34, were tested in field nurseries. NB-LRR3 mapped near the maximum LOD for reduction in stem rust severity in both populations. Lines from a population that segregated for Sr12 and Lr34 were tested for seedling Pgt biomass and infection type, as well as APR to field stem rust which showed an interaction between the genes. We concluded that Sr12, or a gene closely linked to Sr12, was responsible for 'Thatcher'-derived APR in several environments and this resistance was enhanced in the presence of Lr34.

Genomic and pedigree-based prediction for leaf, stem, and stripe rust resistance in wheat.

Science.gov (United States)

Juliana, Philomin; Singh, Ravi P; Singh, Pawan K; Crossa, Jose; Huerta-Espino, Julio; Lan, Caixia; Bhavani, Sridhar; Rutkoski, Jessica E; Poland, Jesse A; Bergstrom, Gary C; Sorrells, Mark E

2017-07-01

Genomic prediction for seedling and adult plant resistance to wheat rusts was compared to prediction using few markers as fixed effects in a least-squares approach and pedigree-based prediction. The unceasing plant-pathogen arms race and ephemeral nature of some rust resistance genes have been challenging for wheat (Triticum aestivum L.) breeding programs and farmers. Hence, it is important to devise strategies for effective evaluation and exploitation of quantitative rust resistance. One promising approach that could accelerate gain from selection for rust resistance is 'genomic selection' which utilizes dense genome-wide markers to estimate the breeding values (BVs) for quantitative traits. Our objective was to compare three genomic prediction models including genomic best linear unbiased prediction (GBLUP), GBLUP A that was GBLUP with selected loci as fixed effects and reproducing kernel Hilbert spaces-markers (RKHS-M) with least-squares (LS) approach, RKHS-pedigree (RKHS-P), and RKHS markers and pedigree (RKHS-MP) to determine the BVs for seedling and/or adult plant resistance (APR) to leaf rust (LR), stem rust (SR), and stripe rust (YR). The 333 lines in the 45th IBWSN and the 313 lines in the 46th IBWSN were genotyped using genotyping-by-sequencing and phenotyped in replicated trials. The mean prediction accuracies ranged from 0.31-0.74 for LR seedling, 0.12-0.56 for LR APR, 0.31-0.65 for SR APR, 0.70-0.78 for YR seedling, and 0.34-0.71 for YR APR. For most datasets, the RKHS-MP model gave the highest accuracies, while LS gave the lowest. GBLUP, GBLUP A, RKHS-M, and RKHS-P models gave similar accuracies. Using genome-wide marker-based models resulted in an average of 42% increase in accuracy over LS. We conclude that GS is a promising approach for improvement of quantitative rust resistance and can be implemented in the breeding pipeline.

Lr67/Yr46 confers adult plant resistance to stem rust and powdery mildew in wheat.

Science.gov (United States)

Herrera-Foessel, Sybil A; Singh, Ravi P; Lillemo, Morten; Huerta-Espino, Julio; Bhavani, Sridhar; Singh, Sukhwinder; Lan, Caixia; Calvo-Salazar, Violeta; Lagudah, Evans S

2014-04-01

We demonstrate that Lr67/Yr46 has pleiotropic effect on stem rust and powdery mildew resistance and is associated with leaf tip necrosis. Genes are designated as Sr55, Pm46 and Ltn3 , respectively. Wheat (Triticum aestivum) accession RL6077, known to carry the pleiotropic slow rusting leaf and yellow rust resistance genes Lr67/Yr46 in Thatcher background, displayed significantly lower stem rust (P. graminis tritici; Pgt) and powdery mildew (Blumeria graminis tritici; Bgt) severities in Kenya and in Norway, respectively, compared to its recurrent parent Thatcher. We investigated the resistance of RL6077 to stem rust and powdery mildew using Avocet × RL6077 F6 recombinant inbred lines (RILs) derived from two photoperiod-insensitive F3 families segregating for Lr67/Yr46. Greenhouse seedling tests were conducted with Mexican Pgt race RTR. Field evaluations were conducted under artificially initiated stem rust epidemics with Pgt races RTR and TTKST (Ug99 + Sr24) at Ciudad Obregon (Mexico) and Njoro (Kenya) during 2010-2011; and under natural powdery mildew epiphytotic in Norway at Ås and Hamar during 2011 and 2012. In Mexico, a mean reduction of 41 % on stem rust severity was obtained for RILs carrying Lr67/Yr46, compared to RILs that lacked the gene, whereas in Kenya the difference was smaller (16 %) but significant. In Norway, leaf tip necrosis was associated with Lr67/Yr46 and RILs carrying Lr67/Yr46 showed a 20 % reduction in mean powdery mildew severity at both sites across the 2 years of evaluation. Our study demonstrates that Lr67/Yr46 confers partial resistance to stem rust and powdery mildew and is associated with leaf tip necrosis. The corresponding pleiotropic, or tightly linked, genes, designated as Sr55, Pm46, and Ltn3, can be utilized to provide broad-spectrum durable disease resistance in wheat.

Effects of neolignans from the stem bark of Magnolia obovata on plant pathogenic fungi.

Science.gov (United States)

Choi, N H; Choi, G J; Min, B-S; Jang, K S; Choi, Y H; Kang, M S; Park, M S; Choi, J E; Bae, B K; Kim, J-C

2009-06-01

To characterize antifungal principles from the methanol extract of Magnolia obovata and to evaluate their antifungal activities against various plant pathogenic fungi. Four neolignans were isolated from stem bark of M. obovata as antifungal principles and identified as magnolol, honokiol, 4-methoxyhonokiol and obovatol. In mycelial growth inhibition assay, both magnolol and honokiol displayed more potent antifungal activity than 4-methoxyhonokiol and obovatol. Both magnolol and honokiol showed similar in vivo antifungal spectrum against seven plant diseases tested; both compounds effectively suppressed the development of rice blast, tomato late blight, wheat leaf rust and red pepper anthracnose. 4-Methoxyhonokiol and obovatol were highly active to only rice blast and wheat leaf rust respectively. The extract of M. obovata and four neolignans had potent in vivo antifungal activities against plant pathogenic fungi. Neolignans from Magnolia spp. can be used and suggested as a novel antifungal lead compound for the development of new fungicide and directly as a natural fungicide for the control of plant diseases such as rice blast and wheat leaf rust.

Rust scoring guide

NARCIS (Netherlands)

Anonymous,

1986-01-01

This brief guide for identifying rust diseases of smaill grain cereals contains color photos depicting the growth stages of small grain cereal crops and provides instructions for recording rust severity and field response for stripe rust (Puccinia striiformis), stem rust (P. graminis), and leaf rust

Major Gene for Field Stem Rust Resistance Co-Locates with Resistance Gene Sr12 in ‘Thatcher’ Wheat

Science.gov (United States)

Hiebert, Colin W.; Kolmer, James A.; McCartney, Curt A.; Briggs, Jordan; Fetch, Tom; Bariana, Harbans; Choulet, Frederic; Rouse, Matthew N.; Spielmeyer, Wolfgang

2016-01-01

Stem rust, caused by Puccinia graminis (Pgt), is a damaging disease of wheat that can be controlled by utilizing effective stem rust resistance genes. ‘Thatcher’ wheat carries complex resistance to stem rust that is enhanced in the presence of the resistance gene Lr34. The purpose of this study was to examine APR in ‘Thatcher’ and look for genetic interactions with Lr34. A RIL population was tested for stem rust resistance in field nurseries in Canada, USA, and Kenya. BSA was used to find SNP markers associated with reduced stem rust severity. A major QTL was identified on chromosome 3BL near the centromere in all environments. Seedling testing showed that Sr12 mapped to the same region as the QTL for APR. The SNP markers were physically mapped and the region carrying the resistance was searched for sequences with homology to members of the NB-LRR resistance gene family. SNP marker from one NB-LRR-like sequence, NB-LRR3 co-segregated with Sr12. Two additional populations, including one that lacked Lr34, were tested in field nurseries. NB-LRR3 mapped near the maximum LOD for reduction in stem rust severity in both populations. Lines from a population that segregated for Sr12 and Lr34 were tested for seedling Pgt biomass and infection type, as well as APR to field stem rust which showed an interaction between the genes. We concluded that Sr12, or a gene closely linked to Sr12, was responsible for ‘Thatcher’-derived APR in several environments and this resistance was enhanced in the presence of Lr34. PMID:27309724

Rust scoring guide

OpenAIRE

Anonymous

1986-01-01

This brief guide for identifying rust diseases of smaill grain cereals contains color photos depicting the growth stages of small grain cereal crops and provides instructions for recording rust severity and field response for stripe rust (Puccinia striiformis), stem rust (P. graminis), and leaf rust (P. recondita).

Molecular Characterization of wheat stem rust races in Kenya

Science.gov (United States)

Stem or black rust caused by Puccinia graminis f. sp. tritici (Pgt) Erikss. & Henning causes severe losses to wheat (Triticum aestivum L.), historically threatening global wheat production. Characterizing prevalent isolates of Pgt would enhance the knowledge of population dynamics and evolution of t...

Studies on stem and leaf rust resistance in wheat

International Nuclear Information System (INIS)

Knott, D.R.

1983-01-01

Stem and leaf rust resistance was successfully transferred from Agropyron to wheat by radiation-induced translocations. Mutation induction subsequently proved to be useful in separating an undesired gene for yellow pigment from the resistance. The homoeologous pairing mutant obtained by Sears was also used successfully in obtaining transfers through crossing-over between wheat and Agropyron chromosomes. Another experimental series succeeded in accumulating minor genes for rust resistance, after eliminating major genes for specific resistance. The resistance is polygenic and widely effective although not general. It is recessively inherited, and hoped to be more durable than major gene resistance used so far in the Canadian prairies. An attempt to induce mutations for leaf rust resistance in a small-scale experiment with leading Canadian wheat varieties Manitou and Neepawa using gamma rays and EMS has not been successful. (author)

Stem and stripe rust resistance in wheat induced by gamma rays and thermal neutrons

International Nuclear Information System (INIS)

Skorda, E.A.

1977-01-01

Attempts were made to produce rust-resistant mutants in wheat cultivars. Seeds of G-38290 and G-58383 (T. aestivum), Methoni and Ilectra (T. durum) varieties were irradiated with different doses of γ-rays (3.5, 5, 8, 11, 15 and 21 krad) and thermal neutrons (1.7, 4, 5.5, 7.5, 10.5 and 12.5x10 12 ) and the M 1 plants were grown under isolation in the field. The objective was mainly to induce stripe, leaf and stem rust resistance in G-38290, Methoni and Ilectra varieties and leaf rust resistance in G-58383. Mutations for rust resistance were detected by using the ''chimera method'' under natural and artificial field epiphytotic conditions in M 2 and successive generations. The mutants detected were tested for resistance to a broad spectrum of available races. Mutants resistant or moderately resistant to stripe and stem rusts but not to leaf rust, were selected from G-38290. From the other three varieties tested no rust-resistant mutants were detected. The frequency of resistant mutants obtained increased with increased γ-ray dose-rate, but not with increased thermal neutron doses. Some mutants proved to be resistant or moderately resistant to both rusts and others to one of them. Twenty of these mutants were evaluated for yield from M 5 to M 8 . Some of them have reached the final stage of regional yield trials and one, induced by thermal neutrons, was released this year. (author)

Characterization of non-host resistance in broad bean to the wheat stripe rust pathogen

Directory of Open Access Journals (Sweden)

Cheng Yulin

2012-06-01

Full Text Available Abstract Background Non-host resistance (NHR confers plant species immunity against the majority of microbial pathogens and represents the most robust and durable form of plant resistance in nature. As one of the main genera of rust fungi with economic and biological importance, Puccinia infects almost all cereals but is unable to cause diseases on legumes. Little is known about the mechanism of this kind of effective defense in legumes to these non-host pathogens. Results In this study, the basis of NHR in broad bean (Vicia faba L. against the wheat stripe rust pathogen, Puccinia striiformis f. sp. tritici (Pst, was characterized. No visible symptoms were observed on broad bean leaves inoculated with Pst. Microscopic observations showed that successful location of stomata and haustoria formation were significantly reduced in Pst infection of broad bean. Attempted infection induced the formation of papillae, cell wall thickening, production of reactive oxygen species, callose deposition and accumulation of phenolic compounds in plant cell walls. The few Pst haustoria that did form in broad bean cells were encased in reactive oxygen and callose materials and those cells elicited cell death. Furthermore, a total of seven defense-related genes were identified and found to be up-regulated during the Pst infection. Conclusions The results indicate that NHR in broad bean against Pst results from a continuum of layered defenses, including basic incompatibility, structural and chemical strengthening of cell wall, posthaustorial hypersensitive response and induction of several defense-related genes, demonstrating the multi-layered feature of NHR. This work also provides useful information for further determination of resistance mechanisms in broad bean to rust fungi, especially the adapted important broad bean rust pathogen, Uromyces viciae-fabae, because of strong similarity and association between NHR of plants to unadapted pathogens and basal

Transformation of the flax rust fungus, Melampsora lini: selection via silencing of an avirulence gene

OpenAIRE

Lawrence, Gregory J.; Dodds, Peter N.; Ellis, Jeffrey G.

2009-01-01

Rust fungi cause devastating diseases on many important food crops, with a damaging stem rust epidemic currently affecting wheat production in Africa and the Middle East. These parasitic fungi propagate exclusively on plants, precluding the use of many biotechnological tools available for other culturable fungi. In particular the lack of a stable transformation system has been an impediment to the genetic manipulation required for molecular analysis of rust pathogenicity. We have developed an...

Molecular Cytogenetic Characterization of two Triticum–Secale–Thinopyrum Trigeneric Hybrids Exhibiting Superior Resistance to Fusarium Head Blight, Leaf Rust, and Stem Rust Race Ug99

Directory of Open Access Journals (Sweden)

Yi Dai

2017-05-01

Full Text Available Fusarium head blight (FHB, leaf rust, and stem rust are the most destructive fungal diseases in current world wheat production. The diploid wheatgrass, Thinopyrum elongatum (Host Dewey (2n = 2x = 14, EE is an excellent source of disease resistance genes. Two new Triticum–Secale–Thinopyrum trigeneric hybrids were derived from a cross between a hexaploid triticale (X Triticosecale Wittmack, 2n = 6x = 42, AABBRR and a hexaploid Triticum trititrigia (2n = 6x = 42, AABBEE, were produced and analyzed using genomic in situ hybridization and molecular markers. The results indicated that line RE21 contained 14 A-chromosomes, 14 B-chromosomes, three pairs of R-chromosomes (4R, 6R, and 7R, and four pairs of E-chromosomes (1E, 2E, 3E, and 5E for a total chromosome number of 2n = 42. Line RE62 contained 14 A-chromosomes, 14 B-chromosomes, six pairs of R-chromosomes, and one pair of translocation chromosomes between chromosome 5R and 5E, for a total chromosome number of 2n = 42. At the seedling and adult growth stages under greenhouse conditions, line RE21 showed high levels of resistance to FHB, leaf rust, and stem rust race Ug99, and line RE62 was highly resistant to leaf rust and stem rust race Ug99. These two lines (RE21 and RE62 display superior disease resistance characteristics and have the potential to be utilized as valuable germplasm sources for future wheat improvement.

Molecular Cytogenetic Characterization of two Triticum-Secale-Thinopyrum Trigeneric Hybrids Exhibiting Superior Resistance to Fusarium Head Blight, Leaf Rust, and Stem Rust Race Ug99.

Science.gov (United States)

Dai, Yi; Duan, Yamei; Liu, Huiping; Chi, Dawn; Cao, Wenguang; Xue, Allen; Gao, Yong; Fedak, George; Chen, Jianmin

2017-01-01

Fusarium head blight (FHB), leaf rust, and stem rust are the most destructive fungal diseases in current world wheat production. The diploid wheatgrass, Thinopyrum elongatum (Host) Dewey (2 n = 2 x = 14, EE) is an excellent source of disease resistance genes. Two new Triticum-Secale-Thinopyrum trigeneric hybrids were derived from a cross between a hexaploid triticale (X Triticosecale Wittmack, 2 n = 6 x = 42, AABBRR) and a hexaploid Triticum trititrigia (2 n = 6 x = 42, AABBEE), were produced and analyzed using genomic in situ hybridization and molecular markers. The results indicated that line RE21 contained 14 A-chromosomes, 14 B-chromosomes, three pairs of R-chromosomes (4R, 6R, and 7R), and four pairs of E-chromosomes (1E, 2E, 3E, and 5E) for a total chromosome number of 2 n = 42. Line RE62 contained 14 A-chromosomes, 14 B-chromosomes, six pairs of R-chromosomes, and one pair of translocation chromosomes between chromosome 5R and 5E, for a total chromosome number of 2 n = 42. At the seedling and adult growth stages under greenhouse conditions, line RE21 showed high levels of resistance to FHB, leaf rust, and stem rust race Ug99, and line RE62 was highly resistant to leaf rust and stem rust race Ug99. These two lines (RE21 and RE62) display superior disease resistance characteristics and have the potential to be utilized as valuable germplasm sources for future wheat improvement.

Stem rust seedling resistance genes in Ethiopian wheat cultivars ...

African Journals Online (AJOL)

Thirty durum wheat (19 commercial cultivars and 11 breeding lines) and 30 bread wheat (20 commercial cultivars and 10 breeding lines) were tested for gene postulation. Stem rust infection types produced on wheat cultivars and breeding lines by ten Pgt races was compared with infection types produced on 40 near ...

Genomic Selection for Quantitative Adult Plant Stem Rust Resistance in Wheat

Directory of Open Access Journals (Sweden)

Jessica E. Rutkoski

2014-11-01

Full Text Available Quantitative adult plant resistance (APR to stem rust ( f. sp. is an important breeding target in wheat ( L. and a potential target for genomic selection (GS. To evaluate the relative importance of known APR loci in applying GS, we characterized a set of CIMMYT germplasm at important APR loci and on a genome-wide profile using genotyping-by-sequencing (GBS. Using this germplasm, we describe the genetic architecture and evaluate prediction models for APR using data from the international Ug99 stem rust screening nurseries. Prediction models incorporating markers linked to important APR loci and seedling phenotype scores as fixed effects were evaluated along with the classic prediction models: Multiple linear regression (MLR, Genomic best linear unbiased prediction (G-BLUP, Bayesian Lasso (BL, and Bayes Cπ (BCπ. We found the region to play an important role in APR in this germplasm. A model using linked markers as fixed effects in G-BLUP was more accurate than MLR with linked markers (-value = 0.12, and ordinary G-BLUP (-value = 0.15. Incorporating seedling phenotype information as fixed effects in G-BLUP did not consistently increase accuracy. Overall, levels of prediction accuracy found in this study indicate that GS can be effectively applied to improve stem rust APR in this germplasm, and if genotypes at linked markers are available, modeling these genotypes as fixed effects could lead to better predictions.

Using hierarchical clustering of secreted protein families to classify and rank candidate effectors of rust fungi.

Directory of Open Access Journals (Sweden)

Diane G O Saunders

Full Text Available Rust fungi are obligate biotrophic pathogens that cause considerable damage on crop plants. Puccinia graminis f. sp. tritici, the causal agent of wheat stem rust, and Melampsora larici-populina, the poplar leaf rust pathogen, have strong deleterious impacts on wheat and poplar wood production, respectively. Filamentous pathogens such as rust fungi secrete molecules called disease effectors that act as modulators of host cell physiology and can suppress or trigger host immunity. Current knowledge on effectors from other filamentous plant pathogens can be exploited for the characterisation of effectors in the genome of recently sequenced rust fungi. We designed a comprehensive in silico analysis pipeline to identify the putative effector repertoire from the genome of two plant pathogenic rust fungi. The pipeline is based on the observation that known effector proteins from filamentous pathogens have at least one of the following properties: (i contain a secretion signal, (ii are encoded by in planta induced genes, (iii have similarity to haustorial proteins, (iv are small and cysteine rich, (v contain a known effector motif or a nuclear localization signal, (vi are encoded by genes with long intergenic regions, (vii contain internal repeats, and (viii do not contain PFAM domains, except those associated with pathogenicity. We used Markov clustering and hierarchical clustering to classify protein families of rust pathogens and rank them according to their likelihood of being effectors. Using this approach, we identified eight families of candidate effectors that we consider of high value for functional characterization. This study revealed a diverse set of candidate effectors, including families of haustorial expressed secreted proteins and small cysteine-rich proteins. This comprehensive classification of candidate effectors from these devastating rust pathogens is an initial step towards probing plant germplasm for novel resistance components.

Sources of stem rust resistance in Ethiopian tetraploid wheat ...

African Journals Online (AJOL)

Stem or black rust of wheat caused by the fungus Puccinia graminis f. sp. tritici Ericks and Henn (Pgt) is an important disease on wheat worldwide. Pgt is an obligate biotroph, heteroceous in its life cycle and heterothallic in mating type. Seedlings of 41 emmer (Triticum dicoccum), 56 durum (T. durum) wheat accessions were ...

Discovery of a novel stem rust resistance allele in durum wheat that exhibits differential reactions to Ug99 isolates

Science.gov (United States)

Wheat stem rust, caused by Puccinia graminis f. sp. tritici Erikss. & E. Henn, can incur yield losses on susceptible cultivars of durum wheat, Triticum turgidum ssp. durum (Desf.) Husnot. Though several durum cultivars possess the stem rust resistance gene Sr13, additional genes in durum wheat effec...

Studies of the genetics of inheritance of stem rust resistance in ...

African Journals Online (AJOL)

User

2013-05-22

May 22, 2013 ... increased production of wheat could help to ensure food and nutritional ... also characterized by genes with additive effects and non hypersensitive .... to create an artificial stem rust epidemic in the field (Hickey et al.,. 2012 ...

Stem rust (Puccinia graminis ssp. graminicola Urban its hosts and harmfulness in grasses grown for seed

Directory of Open Access Journals (Sweden)

Maria Prończuk

2013-12-01

Full Text Available Stem rust development on four species of grasses was studied in field experiments conducted at Radzików in 1997-2001. Population of Puccinia graminis ssp. graminicola from different hosts was characterised and their harmfulness for grass grown for seed was estimated. The materials for study were ecotypes and strains of Lolium perenne, Festuca rubra, Poa pratensis and Deschampsia caespitosa collected in breeding nursery and cultivars and strains of L.perenne, F.rubra, P.pratensis cultivated for seed. It was found that the changes in environmental conditions during last years influenced earlier occurrence of stem rust on grasses in Poland. All examined species were the host of P.graminis ssp. graminicola, however the period of infection of particular hosts were different. L.perenne and D.caespitosa were infected in early summer but F.rubra and P.pratensis in late summer or in the autumn. Morphological analysis of spores of P.graminis ssp. graminicola have shoved significant differences between populations obtained from L.perenne and D.caespitosa. Some differences were found between populations from F.rubra and P.pratensis also, but they need more study. Every year occurrence of stem rust on L.perenne and D.caespitosa and its relation with spring temperature in Radzików indicated that populations of patogen could overwinter in local turf. Incidental appearance of stem rust on F.rubra and P.pratensis in centre of Poland allowed to suppose that spores of these forms might be transfer by wind from other regions. The investigation revealed that stem rust can be dangerous for L.perenne grown for seed when infection occurs at flowering time. It has been established that infection of F.rubra and P.pratensis in autumn should not be disregarded. Damages of leaves by P.graminis ssp. graminicola substantially limited plant heading in the next year.

Sources of stem rust resistance in wheat-alien introgression lines

Science.gov (United States)

Stem rust, caused by Puccinia graminis f. sp. tritici, is one of the most devastating diseases of wheat and the novel highly virulent race of TTKSK and its lineage are threatening wheat production worldwide. The objective of the study was to identify new sources of resistance in wheat-alien introgre...

Genetic mapping of stem rust resistance to Puccinia graminis f. sp. tritici race TRTTF in the Canadian wheat cultivar 'Harvest'

Science.gov (United States)

Stem rust, caused by Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn.(Pgt), is a destructive disease of wheat that can be controlled by deploying effective stem rust resistance (Sr) genes. Highly virulent races of Pgt in Africa have been detected and characterized. These include race T...

Seedling Resistance to Stem Rust and Molecular Marker Analysis of Resistance Genes in Wheat Cultivars of Yunnan, China.

Directory of Open Access Journals (Sweden)

Tian Ya Li

Full Text Available Stem rust is one of the most potentially harmful wheat diseases, but has been effectively controlled in China since 1970s. However, the interest in breeding wheat with durable resistance to stem rust has been renewed with the emergence of Ug99 (TTKSK virulent to the widely used resistance gene Sr31, and by which the wheat stem rust was controlled for 40 years in wheat production area worldwide. Yunnan Province, located on the Southwest border of China, is one of the main wheat growing regions, playing a pivotal role in the wheat stem rust epidemic in China. This study investigated the levels of resistance in key wheat cultivars (lines of Yunnan Province. In addition, the existence of Sr25, Sr26, Sr28, Sr31, Sr32, and Sr38 genes in 119 wheat cultivars was assessed using specific DNA markers. The results indicated that 77 (64.7% tested wheat varieties showed different levels of resistance to all the tested races of Puccinia graminis f. sp. tritici. Using molecular markers, we identified the resistance gene Sr31 in 43 samples; Sr38 in 10 samples; Sr28 in 12 samples, and one sample which was resistant against Ug99 (avirulent to Sr32. No Sr25 or Sr26 (effective against Ug99 was identified in any cultivars tested. Furthermore, 5 out of 119 cultivars tested carried both Sr31 and Sr38 and eight contained both Sr31 and Sr28. The results enable the development of appropriate strategies to breed varieties resistant to stem rust.

Taxonomy, phylogeny, and coevolution of pines and their stem rusts

Science.gov (United States)

C. I. Millar; B. B. Kinloch

1991-01-01

We review and reinterpret major events in the evolution of pines and their stem rusts using information from their taxonomy, genetics, biogeography, and fossil history. Understanding of pine evolution has been significantly revised in the last 20 years. Pines appear to have evolved early in the Mesozoic and to have diversified and migrated throughout middle latitudes...

Wheat Rust Toolbox Related to New Initiatives on Yellow Rust

DEFF Research Database (Denmark)

Hansen, Jens Grønbech; Lassen, Poul

://www.fao.org/agriculture/crops/rust/stem/rust-report/en/). The Wheat rust toolbox is one of several International research platforms hosted by Aarhus University, and it uses the same ICT framework and databases as EuroWheat (www.eurowheat.org) and EuroBlight (www.EuroBlight.net). The Wheat Rust Toolbox will also serve the Global Rust Reference Centre (GRRC) as well...... – 2009), and as soon as possible this will be expanded to cover all global yellow rust data available via the GRRC. The presentation will focus on experiences from the previous work on global databases and web based information systems, as well as propose ideas how the toolbox can be helpful regarding...

Race-Specific Adult-Plant Resistance in Winter Wheat to Stripe Rust and Characterization of Pathogen Virulence Patterns.

Science.gov (United States)

Milus, Eugene A; Moon, David E; Lee, Kevin D; Mason, R Esten

2015-08-01

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is an important disease of wheat in the Great Plains and southeastern United States. Growing resistant cultivars is the preferred means for managing stripe rust, but new virulence in the pathogen population overcomes some of the resistance. The objectives of this study were to characterize the stripe rust resistance in contemporary soft and hard red winter wheat cultivars, to characterize the virulence of P. striiformis f. sp. tritici isolates based on the resistances found in the cultivars, and to determine wheat breeders' perceptions on the importance and methods for achieving stripe rust resistance. Seedlings of cultivars were susceptible to recent isolates, indicating they lacked effective all-stage resistance. However, adult-plants were resistant or susceptible depending on the isolate, indicating they had race-specific adult-plant resistance. Using isolates collected from 1990 to 2013, six major virulence patterns were identified on adult plants of twelve cultivars that were selected as adult-plant differentials. Race-specific adult-plant resistance appears to be the only effective type of resistance protecting wheat from stripe rust in eastern United States. Among wheat breeders, the importance of incorporating stripe rust resistance into cultivars ranged from high to low depending on the frequency of epidemics in their region, and most sources of stripe rust resistance were either unknown or already overcome by virulence in the pathogen population. Breeders with a high priority for stripe rust resistance made most of their selections based on adult-plant reactions in the field, whereas breeders with a low priority for resistance based selections on molecular markers for major all-stage resistance genes.

Plant-pathogen interactions: leaf physiology alterations in poplars infected with rust (Melampsora medusae).

Science.gov (United States)

Gortari, Fermín; Guiamet, Juan José; Graciano, Corina

2018-01-23

Rust produced by Melampsora sp. is considered one of the most relevant diseases in poplar plantations. Growth reduction in poplar plantations takes place because rust, like other pathogens, alters leaf physiology. There is not a complete evaluation of several of the physiological traits that can be affected by rust at leaf level. Therefore, the aim of this work was to evaluate, in an integrative way and in the same pathosystem, which physiological processes are affected when Populus deltoides Bartr. ex Marsh. leaves are infected by rust (Melampsora medusae Thümen). Leaves of two clones with different susceptibility to rust were analyzed. Field and pot experiments were performed, and several physiological traits were measured in healthy and infected leaves. We conclude that rust affects leaf mesophyll integrity, and so water movement in the leaf in liquid phase is affected. As a consequence, gas exchange is reduced, affecting both carbon fixation and transpiration. However, there is an increase in respiration rate, probably due to plant and fungal respiration. The increase in respiration rate is important in the reduction of net photosynthetic rate, but also some damage in the photosynthetic apparatus limits leaf capacity to fix carbon. The decrease in chlorophyll content would start later and seems not to explain the reduction in net photosynthetic rate. Both clones, although they have different susceptibility to rust, are affected in the same physiological mechanisms. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Characterization of stem rust resistance gene Sr2 in Indian wheat ...

African Journals Online (AJOL)

SONY

2013-05-01

May 1, 2013 ... accelerating wheat production in the last forty years and ensured food security of the Nation. In the present investigation, Sr2 specific molecular markers were used to assess their efficacy for assessing the deployment of Sr2 gene in Indian wheat cultivars of highly productive north-west plains and stem rust ...

Molecular and genetic study of wheat rusts | Le Maitre | African ...

African Journals Online (AJOL)

Microsatellite markers were used to differentiate P. triticina and P. striiformis pathotypes. Amplified fragment length polymorphisms (AFLP) were used to differentiate stem rust P. graminis pathotypes. Phylogenetic trees were created for leaf and stem rust pathotypes. Field isolates of leaf, stem and yellow rust were collected ...

Determination of rust resistance genes in pakistani bread wheats

International Nuclear Information System (INIS)

Qamar, M.; Ahmad, S.D.; Rabbani, M.A.; Shinwari, Z.K.

2014-01-01

Stripe and leaf rusts are the major constraints to bread wheat production in Pakistan. Molecular markers were used to investigate the presence of leaf rust and stripe rust resistance gene cluster Lr34/Yr18 and stem rust resistance gene Sr2 in 52 Pakistani bread wheat cultivars/lines. PCR amplification of DNA fragments using DNA marker csLV-34 showed that 13 of the studied cultivars/lines, namely 03FJ26, NR 337, NR 339, NR 347, NR 350, Manthar, Margalla 99, Iqbal 2000, Saleem 2000, Wafaq 2001, Marwat 2001, Pirsabak 2004 and Fareed 2006 carry leaf rust and stripe rust resistance genes Lr34/Yr18. Stem rust resistance gene Sr2 was observed in 36 Pakistani spring wheat cultivars/lines using stm560.3tgag marker. The slow rusting gene Sr2 needs to be combined with additional stem rust resistance genes to establish durable resistance against Ug99 in modern wheat cultivars. Low frequency of Lr34/Yr18 was found in Pakistani wheats. This gene cluster needs to be incorporated into Pakistani wheats for durable rust resistance. (author)

Screening oat populations for rust resistant mutants

International Nuclear Information System (INIS)

McKenzie, R.I.H.; Martens, J.W.; Harder, D.E.; Brown, P.D.

1976-01-01

In 1972 a two million M 2 plants were grown at Morden, Manitoba. Thirteen plants which were thought to have possible resistance to race CI0 of oat stem rust were harvested. After extensive seedling and adult plant rust tests the best of the selected plant progenies was crossed and backcrossed to Rodney 0, a stem rust susceptible oat. The resistance in this line M-72-6 was found to be controlled by a single gene. In 1973 another two million M 2 plants were examined for rust resistance at Morden and 38 were harvested. None of the M 2 plants selected in 1973 appeared to have any seedling or adult resistance when examined more thoroughly in the greenhouse and again in the field in 1974. In 1974 one million M 2 plants were examined for resistance and 73 selected. None appeared to have any resistance when tested further. The strain CI3034 which was good adult plant stem rust resistance associated with weak straw and a light green plant colour was treated with gamma radiation and EMS in 1973 and the M 2 grown in the C10 rust nursery at Morden in 1974. A considerable number of dark green plants were present in all treatments but unfortunately all were found to be stem rust susceptible. Thus it would appear to be difficult if not impossible to separate the rust resistance in CI3034 from the undesirable characters, weak straw and light green plant colour. (author)

Mapping and characterization of wheat stem rust resistance genes SrTm5 and Sr60 from Triticum monococcum.

Science.gov (United States)

Chen, Shisheng; Guo, Yan; Briggs, Jordan; Dubach, Felix; Chao, Shiaoman; Zhang, Wenjun; Rouse, Matthew N; Dubcovsky, Jorge

2018-03-01

The new stem rust resistance gene Sr60 was fine-mapped to the distal region of chromosome arm 5A m S, and the TTKSK-effective gene SrTm5 could be a new allele of Sr22. The emergence and spread of new virulent races of the wheat stem rust pathogen (Puccinia graminis f. sp. tritici; Pgt), including the Ug99 race group, is a serious threat to global wheat production. In this study, we mapped and characterized two stem rust resistance genes from diploid wheat Triticum monococcum accession PI 306540. We mapped SrTm5, a previously postulated gene effective to Ug99, on chromosome arm 7A m L, completely linked to Sr22. SrTm5 displayed a different race specificity compared to Sr22 indicating that they are distinct. Sequencing of the Sr22 homolog in PI 306540 revealed a novel haplotype. Characterization of the segregating populations with Pgt race QFCSC revealed an additional resistance gene on chromosome arm 5A m S that was assigned the official name Sr60. This gene was also effective against races QTHJC and SCCSC but not against TTKSK (a Ug99 group race). Using two large mapping populations (4046 gametes), we mapped Sr60 within a 0.44 cM interval flanked by sequenced-based markers GH724575 and CJ942731. These two markers delimit a 54.6-kb region in Brachypodium distachyon chromosome 4 and a 430-kb region in the Chinese Spring reference genome. Both regions include a leucine-rich repeat protein kinase (LRRK123.1) that represents a potential candidate gene. Three CC-NBS-LRR genes were found in the colinear Brachypodium region but not in the wheat genome. We are currently developing a Bacterial Artificial Chromosome library of PI 306540 to determine which of these candidate genes are present in the T. monococcum genome and to complete the cloning of Sr60.

Cytological and molecular analysis of nonhost resistance in rice to wheat powdery mildew and leaf rust pathogens.

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Cheng, Yulin; Yao, Juanni; Zhang, Hongchang; Huang, Lili; Kang, Zhensheng

2015-07-01

Cereal powdery mildews caused by Blumeria graminis and cereal rusts caused by Puccinia spp. are constant disease threats that limit the production of almost all important cereal crops. Rice is an intensively grown agricultural cereal that is atypical because of its immunity to all powdery mildew and rust fungi. We analyzed the nonhost interactions between rice and the wheat powdery mildew fungus B. graminis f. sp. tritici (Bgt) and the wheat leaf rust fungus Puccinia triticina (Ptr) to identify the basis of nonhost resistance (NHR) in rice against cereal powdery mildew and rust fungi at cytological and molecular levels. No visible symptoms were observed on rice leaves inoculated with Bgt or Ptr. Microscopic observations showed that both pathogens exhibited aberrant differentiation and significantly reduced penetration frequencies on rice compared to wheat. The development of Bgt and Ptr was also completely arrested at early infection stages in cases of successful penetration into rice leaves. Attempted infection of rice by Bgt and Ptr induced similar defense responses, including callose deposition, accumulation of reactive oxygen species, and hypersensitive response in rice epidermal and mesophyll cells, respectively. Furthermore, a set of defense-related genes were upregulated in rice against Bgt and Ptr infection. Rice is an excellent monocot model for genetic and molecular studies. Therefore, our results demonstrate that rice is a useful model to study the mechanisms of NHR to cereal powdery mildew and rust fungi, which provides useful information for the development of novel and durable strategies to control these important pathogens.

First report of the white pine blister rust fungus, Cronartium ribicola, infecting Pinus flexilis on Pine Mountain, Humboldt National Forest, Elko County, northeastern Nevada, U.S.A.

Science.gov (United States)

Detlev R. Vogler; Patricia E. Maloney; Tom Burt; Jacob W. Snelling

2017-01-01

In 2013, while surveying for five-needle white pine cone crops in northeastern Nevada, we observed white pine blister rust, caused by the rust pathogen Cronartium ribicola Fisch., infecting branches and stems of limber pines (Pinus flexilis James) on Pine Mountain (41.76975°N, 115.61622°W), Humboldt National Forest,...

Strategies for improving rust resistance in oats

International Nuclear Information System (INIS)

Harder, D.E.; McKenzie, R.I.H.; Martens, J.W.; Brown, P.D.

1977-01-01

During the history of breeding oats for rust resistance in Canada the known sources of resistance proved inadequate to counter the virulence potential of both stem rust (Puccinia graminis avenae) and crown rust (P. coronata avenae). A major programme to overcome the rust problem was undertaken at Winnipeg, involving four alternate approaches: (1) A search for new resistance in wild oat species, particularly Avena sterilis, has provided a wealth of good resistance to crown rust, but less to stem rust. Much of the A. sterilis-derived crown rust resistance is now being used world-wide; (2) Efforts at synthesizing new resistance by mutation breeding methods have not been successful. Of about seven million plants examined, only one showed significant new resistance, but this was associated with poor plant type; (3) Resistance with low levels of expression but which appears broadly effective has been observed against both stem and crown rusts. It appears that numbers of these low-level genes exist, and that they can be accumulated to provide increasingly effective resistance. Problems in using this type of resistance in a practical way are discussed; (4) Excellent rust resistance has been found in lower ploidy species such as A. barbata, but it was not previously possible to stabilize this resistance in hexaploid species. By using mutagenic treatments attempts have been made to translocate smaller portions of the A. barbata chromosome carrying the resistance to the hexaploid cultivar Rodney. In conclusion, mutation breeding methods at present appear to have limited application in synthesizing new rust-resistant genotypes in oats. The search for already existing genetic resistance and its synthesis into multi-genic resistant lines appears to be the most effective way at present of resolving the rust problem in oats. (author)

Multiple genotypes within aecial clusters in Puccinia graminis and Puccinia coronata: improved understanding of the biology of cereal rust fungi.

Science.gov (United States)

Berlin, Anna; Samils, Berit; Andersson, Björn

2017-01-01

Cereal rust fungi ( Puccinia spp.) are among the most economically important plant pathogens. These fungi have a complex life cycle, including five spore stages and two hosts. They infect one grass host on which they reproduce clonally and cause the cereal rust diseases, while the alternate host is required for sexual reproduction. Although previous studies clearly demonstrate the importance of the alternate host in creating genetic diversity in cereal rust fungi, little is known about the amount of novel genotypes created in each successful completion of a sexual reproduction event. In this study, single sequence repeat markers were used to study the genotypic diversity within aecial clusters by genotyping individual aecial cups. Two common cereal rusts, Puccinia graminis causing stem rust and Puccinia coronata the causal agent of crown rust were investigated. We showed that under natural conditions, a single aecial cluster usually include several genotypes, either because a single pycnial cluster is fertilized by several different pycniospores, or because aecia within the cluster are derived from more than one fertilized adjoining pycnial cluster, or a combination of both. Our results imply that although sexual events in cereal rust fungi in most regions of the world are relatively rare, the events that occur may still significantly contribute to the genetic variation within the pathogen populations.

New Seeds are Resistant to Wheat Stem Rust (Ug99) Multinational Programme Supported by FAO and IAEA

International Nuclear Information System (INIS)

2013-01-01

Full text: A multinational effort supported by the International Atomic Energy Agency and the U.N. Food and Agriculture Organization marked a key milestone this week when a Kenyan university debuted two new varieties of disease-resistant wheat to the nation's farmers. Over the past two days, thousands of Kenyan farmers have visited Eldoret University in western Kenya for a two-day agriculture fair highlighting the latest farming technologies. Supporting the development of the new varieties were the IAEA's Technical Cooperation Department and the Joint FAO/IAEA Programme of Nuclear Techniques in Food and Agriculture. They manage an interregional Technical Cooperation project to develop varieties of wheat that are resistant to a devastating type of fungus, causing a disease known as wheat stem rust. Wheat stem rust under control for over 30 years, but a resurgence of the disease was discovered in 1999 in Uganda that swiftly spread to neighbouring Kenya. The wheat stem rust, caused by the strain of the fungus known as Ug99, named after its place and year of origin, has since spread to Iran, Yemen and South Africa and threatens crops as far away as India as spores are carried by wind. Parasitic rusts threaten global wheat production, reducing plant growth and crop yields. The disease can destroy up to 70-100 percent of the yield of wheat crop if not prevented. 'Improving food security in developing countries through the use of nuclear techniques is an important priority of the IAEA', said IAEA Director General Yukiya Amano. 'I am pleased that we have been able to make an important contribution to fighting wheat rust'. 'Wheat rusts, particularly the Ug99 strain, are a major threat to food security because rust epidemics can result in devastating yield losses. This international project involving affected countries, plant scientists and breeders and international organizations is a major breakthrough. It clearly shows the benefits of FAO/IAEA collaboration and that

Virulence and molecular characterization of experimental isolates of the stripe rust pathogen (Puccinia striiformis) indicate somatic recombination

Science.gov (United States)

Puccinia striiformis causes stripe rust on wheat, barley, and grasses. Natural population studies have indicated that somatic recombination plays a possible role in the pathogen variation. To determine if somatic recombination can occur, susceptible wheat or barley plants were inoculated with mixe...

Genetic analysis of rust resistance genes in global wheat cultivars: an overview

International Nuclear Information System (INIS)

Aktar-Uz-Zaman, Md; Tuhina-Khatun, Mst; Hanafi, Mohamed Musa; Sahebi, Mahbod

2017-01-01

Rust is the most devastating fungal disease in wheat. Three rust diseases, namely, leaf or brown rust caused by Puccinia triticina Eriks, stem or black rust caused by Puccinia graminis f. sp. tritici West, and stripe or yellow rust caused by Puccinia striiformis f. Tritici Eriks, are the most economically significant and common diseases among global wheat cultivars. Growing cultivars resistant to rust is the most sustainable, cost-effective and environmentally friendly approach for controlling rust diseases. To date, more than 187 rust resistance genes (80 leaf rust, 58 stem rust and 49 stripe rust) have been derived from diverse wheat or durum wheat cultivars and the related wild species using different molecular methods. This review provides a detailed discussion of the different aspects of rust resistance genes, their primitive sources, their distribution in global wheat cultivars and the importance of durable resistant varieties for controlling rust diseases. This information will serve as a foundation for plant breeders and geneticists to develop durable rust-resistant wheat varieties through marker-assisted breeding or gene pyramiding

Laboratory, greenhouse and field methods for screening rust-resistant wheat cultivars

International Nuclear Information System (INIS)

Mashaal, S.F.; Kiraly, Z.; Barabas, Z.; Barna, B.; Cereal Research Inst., Szeged, Hungary)

1977-01-01

Detached flag leaf cultures were not suitable for evaluation of stem-rust resistance in our screening programme. On the basis of yield evaluation it was possible to screen out ten stem-rust ''tolerant'' wheat lines in field experiments. Rusted and protected microplots of each line were paired within a replicate. After artificial inoculation, the protected plants were sprayed with fungicides (benomyl plus dithiocarbamate plus copper salt) at weekly intervals until maturation to keep each protected plot rust-free. The thousand-kernel weights of rusted and protected plots were compared. When the thousand-kernel weight of protected plot increased only slightly and the rust reaction type of plants was susceptible in the rusted plot, the line was screened out as putative ''tolerant''. On the basis of three-year field trial ten ''tolerant'' lines were selected. Nine out of ten lines proved to be resistant to two stem-rust races in greenhouse tests in the seedling stage, when resistance was determined on the basis of reduced spore production instead of infection types. Resistance of these seedlings related partly to the reduced number of pustules and partly to a slow rusting character of plants. It seems possible to screen resistant cultivars in the greenhouse by the method outlined in this paper, when resistance is determined on the basis of a reduced number of infection sites and/or by the slow rusting capacity. (author)

The Lr34 adult plant rust resistance gene provides seedling resistance in durum wheat without senescence.

Science.gov (United States)

Rinaldo, Amy; Gilbert, Brian; Boni, Rainer; Krattinger, Simon G; Singh, Davinder; Park, Robert F; Lagudah, Evans; Ayliffe, Michael

2017-07-01

The hexaploid wheat (Triticum aestivum) adult plant resistance gene, Lr34/Yr18/Sr57/Pm38/Ltn1, provides broad-spectrum resistance to wheat leaf rust (Lr34), stripe rust (Yr18), stem rust (Sr57) and powdery mildew (Pm38) pathogens, and has remained effective in wheat crops for many decades. The partial resistance provided by this gene is only apparent in adult plants and not effective in field-grown seedlings. Lr34 also causes leaf tip necrosis (Ltn1) in mature adult plant leaves when grown under field conditions. This D genome-encoded bread wheat gene was transferred to tetraploid durum wheat (T. turgidum) cultivar Stewart by transformation. Transgenic durum lines were produced with elevated gene expression levels when compared with the endogenous hexaploid gene. Unlike nontransgenic hexaploid and durum control lines, these transgenic plants showed robust seedling resistance to pathogens causing wheat leaf rust, stripe rust and powdery mildew disease. The effectiveness of seedling resistance against each pathogen correlated with the level of transgene expression. No evidence of accelerated leaf necrosis or up-regulation of senescence gene markers was apparent in these seedlings, suggesting senescence is not required for Lr34 resistance, although leaf tip necrosis occurred in mature plant flag leaves. Several abiotic stress-response genes were up-regulated in these seedlings in the absence of rust infection as previously observed in adult plant flag leaves of hexaploid wheat. Increasing day length significantly increased Lr34 seedling resistance. These data demonstrate that expression of a highly durable, broad-spectrum adult plant resistance gene can be modified to provide seedling resistance in durum wheat. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Genome-Wide Association Study for Identification and Validation of Novel SNP Markers for Sr6 Stem Rust Resistance Gene in Bread Wheat.

Science.gov (United States)

Mourad, Amira M I; Sallam, Ahmed; Belamkar, Vikas; Wegulo, Stephen; Bowden, Robert; Jin, Yue; Mahdy, Ezzat; Bakheit, Bahy; El-Wafaa, Atif A; Poland, Jesse; Baenziger, Peter S

2018-01-01

Stem rust (caused by Puccinia graminis f. sp. tritici Erikss. & E. Henn.), is a major disease in wheat ( Triticum aestivium L.). However, in recent years it occurs rarely in Nebraska due to weather and the effective selection and gene pyramiding of resistance genes. To understand the genetic basis of stem rust resistance in Nebraska winter wheat, we applied genome-wide association study (GWAS) on a set of 270 winter wheat genotypes (A-set). Genotyping was carried out using genotyping-by-sequencing and ∼35,000 high-quality SNPs were identified. The tested genotypes were evaluated for their resistance to the common stem rust race in Nebraska (QFCSC) in two replications. Marker-trait association identified 32 SNP markers, which were significantly (Bonferroni corrected P < 0.05) associated with the resistance on chromosome 2D. The chromosomal location of the significant SNPs (chromosome 2D) matched the location of Sr6 gene which was expected in these genotypes based on pedigree information. A highly significant linkage disequilibrium (LD, r 2 ) was found between the significant SNPs and the specific SSR marker for the Sr6 gene ( Xcfd43 ). This suggests the significant SNP markers are tagging Sr6 gene. Out of the 32 significant SNPs, eight SNPs were in six genes that are annotated as being linked to disease resistance in the IWGSC RefSeq v1.0. The 32 significant SNP markers were located in nine haplotype blocks. All the 32 significant SNPs were validated in a set of 60 different genotypes (V-set) using single marker analysis. SNP markers identified in this study can be used in marker-assisted selection, genomic selection, and to develop KASP (Kompetitive Allele Specific PCR) marker for the Sr6 gene. Novel SNPs for Sr6 gene, an important stem rust resistant gene, were identified and validated in this study. These SNPs can be used to improve stem rust resistance in wheat.

Identification of QTL conferring resistance to stripe rust (Puccinia striiformis f. sp. hordei) and leaf rust (Puccinia hordei) in barley using nested association mapping (NAM).

Science.gov (United States)

Vatter, Thomas; Maurer, Andreas; Perovic, Dragan; Kopahnke, Doris; Pillen, Klaus; Ordon, Frank

2018-01-01

The biotrophic rust fungi Puccinia hordei and Puccinia striiformis are important barley pathogens with the potential to cause high yield losses through an epidemic spread. The identification of QTL conferring resistance to these pathogens is the basis for targeted breeding approaches aiming to improve stripe rust and leaf rust resistance of modern cultivars. Exploiting the allelic richness of wild barley accessions proved to be a valuable tool to broaden the genetic base of resistance of barley cultivars. In this study, SNP-based nested association mapping (NAM) was performed to map stripe rust and leaf rust resistance QTL in the barley NAM population HEB-25, comprising 1,420 lines derived from BC1S3 generation. By scoring the percentage of infected leaf area, followed by calculation of the area under the disease progress curve and the average ordinate during a two-year field trial, a large variability of resistance across and within HEB-25 families was observed. NAM based on 5,715 informative SNPs resulted in the identification of twelve and eleven robust QTL for resistance against stripe rust and leaf rust, respectively. Out of these, eight QTL for stripe rust and two QTL for leaf rust are considered novel showing no overlap with previously reported resistance QTL. Overall, resistance to both pathogens in HEB-25 is most likely due to the accumulation of numerous small effect loci. In addition, the NAM results indicate that the 25 wild donor QTL alleles present in HEB-25 strongly differ in regard to their individual effect on rust resistance. In future, the NAM concept will allow to select and combine individual wild barley alleles from different HEB parents to increase rust resistance in barley. The HEB-25 results will support to unravel the genetic basis of rust resistance in barley, and to improve resistance against stripe rust and leaf rust of modern barley cultivars.

Two distinct classes of QTL determine rust resistance in sorghum.

Science.gov (United States)

Wang, Xuemin; Mace, Emma; Hunt, Colleen; Cruickshank, Alan; Henzell, Robert; Parkes, Heidi; Jordan, David

2014-12-31

Agriculture is facing enormous challenges to feed a growing population in the face of rapidly evolving pests and pathogens. The rusts, in particular, are a major pathogen of cereal crops with the potential to cause large reductions in yield. Improving stable disease resistance is an on-going major and challenging focus for many plant breeding programs, due to the rapidly evolving nature of the pathogen. Sorghum is a major summer cereal crop that is also a host for a rust pathogen Puccinia purpurea, which occurs in almost all sorghum growing areas of the world, causing direct and indirect yield losses in sorghum worldwide, however knowledge about its genetic control is still limited. In order to further investigate this issue, QTL and association mapping methods were implemented to study rust resistance in three bi-parental populations and an association mapping set of elite breeding lines in different environments. In total, 64 significant or highly significant QTL and 21 suggestive rust resistance QTL were identified representing 55 unique genomic regions. Comparisons across populations within the current study and with rust QTL identified previously in both sorghum and maize revealed a high degree of correspondence in QTL location. Negative phenotypic correlations were observed between rust, maturity and height, indicating a trend for both early maturing and shorter genotypes to be more susceptible to rust. The significant amount of QTL co-location across traits, in addition to the consistency in the direction of QTL allele effects, has provided evidence to support pleiotropic QTL action across rust, height, maturity and stay-green, supporting the role of carbon stress in susceptibility to rust. Classical rust resistance QTL regions that did not co-locate with height, maturity or stay-green QTL were found to be significantly enriched for the defence-related NBS-encoding gene family, in contrast to the lack of defence-related gene enrichment in multi-trait effect

Uncovering leaf rust responsive miRNAs in wheat (Triticum aestivum L.) using high-throughput sequencing and prediction of their targets through degradome analysis.

Science.gov (United States)

Kumar, Dhananjay; Dutta, Summi; Singh, Dharmendra; Prabhu, Kumble Vinod; Kumar, Manish; Mukhopadhyay, Kunal

2017-01-01

Deep sequencing identified 497 conserved and 559 novel miRNAs in wheat, while degradome analysis revealed 701 targets genes. QRT-PCR demonstrated differential expression of miRNAs during stages of leaf rust progression. Bread wheat (Triticum aestivum L.) is an important cereal food crop feeding 30 % of the world population. Major threat to wheat production is the rust epidemics. This study was targeted towards identification and functional characterizations of micro(mi)RNAs and their target genes in wheat in response to leaf rust ingression. High-throughput sequencing was used for transcriptome-wide identification of miRNAs and their expression profiling in retort to leaf rust using mock and pathogen-inoculated resistant and susceptible near-isogenic wheat plants. A total of 1056 mature miRNAs were identified, of which 497 miRNAs were conserved and 559 miRNAs were novel. The pathogen-inoculated resistant plants manifested more miRNAs compared with the pathogen infected susceptible plants. The miRNA counts increased in susceptible isoline due to leaf rust, conversely, the counts decreased in the resistant isoline in response to pathogenesis illustrating precise spatial tuning of miRNAs during compatible and incompatible interaction. Stem-loop quantitative real-time PCR was used to profile 10 highly differentially expressed miRNAs obtained from high-throughput sequencing data. The spatio-temporal profiling validated the differential expression of miRNAs between the isolines as well as in retort to pathogen infection. Degradome analysis provided 701 predicted target genes associated with defense response, signal transduction, development, metabolism, and transcriptional regulation. The obtained results indicate that wheat isolines employ diverse arrays of miRNAs that modulate their target genes during compatible and incompatible interaction. Our findings contribute to increase knowledge on roles of microRNA in wheat-leaf rust interactions and could help in rust

29-34 Yellow Rust Resistance in Advanced Lines and Commercial ...

African Journals Online (AJOL)

rust pathogen. The objective of this study was to characterize seedling yellow rust resistance in 21 advanced bread wheat lines and 20 cultivars from Ethiopia. Yellow rust infection types (ITs) produced on test wheat lines and cultivars from nine yellow rust races were compared with ITs produced on standard differential lines ...

Molecular and cytogenetic characterization of wheat introgression lines carrying the stem rust resistance gene Sr39.

Science.gov (United States)

Stem rust, caused by Puccinia graminis Pers.:Pers. f.sp. tritici Eriks. and Henn., poses a serious threat to global wheat production because of the emergence of Pgt-TTKSK (Ug99). The TTKSK resistant gene Sr39 was derived from Aegilops speltoides through chromosome translocation. In this study, we ch...

Identification of QTL conferring resistance to stripe rust (Puccinia striiformis f. sp. hordei) and leaf rust (Puccinia hordei) in barley using nested association mapping (NAM)

Science.gov (United States)

Vatter, Thomas; Maurer, Andreas; Perovic, Dragan; Kopahnke, Doris; Pillen, Klaus

2018-01-01

The biotrophic rust fungi Puccinia hordei and Puccinia striiformis are important barley pathogens with the potential to cause high yield losses through an epidemic spread. The identification of QTL conferring resistance to these pathogens is the basis for targeted breeding approaches aiming to improve stripe rust and leaf rust resistance of modern cultivars. Exploiting the allelic richness of wild barley accessions proved to be a valuable tool to broaden the genetic base of resistance of barley cultivars. In this study, SNP-based nested association mapping (NAM) was performed to map stripe rust and leaf rust resistance QTL in the barley NAM population HEB-25, comprising 1,420 lines derived from BC1S3 generation. By scoring the percentage of infected leaf area, followed by calculation of the area under the disease progress curve and the average ordinate during a two-year field trial, a large variability of resistance across and within HEB-25 families was observed. NAM based on 5,715 informative SNPs resulted in the identification of twelve and eleven robust QTL for resistance against stripe rust and leaf rust, respectively. Out of these, eight QTL for stripe rust and two QTL for leaf rust are considered novel showing no overlap with previously reported resistance QTL. Overall, resistance to both pathogens in HEB-25 is most likely due to the accumulation of numerous small effect loci. In addition, the NAM results indicate that the 25 wild donor QTL alleles present in HEB-25 strongly differ in regard to their individual effect on rust resistance. In future, the NAM concept will allow to select and combine individual wild barley alleles from different HEB parents to increase rust resistance in barley. The HEB-25 results will support to unravel the genetic basis of rust resistance in barley, and to improve resistance against stripe rust and leaf rust of modern barley cultivars. PMID:29370232

Identification of QTL conferring resistance to stripe rust (Puccinia striiformis f. sp. hordei and leaf rust (Puccinia hordei in barley using nested association mapping (NAM.

Directory of Open Access Journals (Sweden)

Thomas Vatter

Full Text Available The biotrophic rust fungi Puccinia hordei and Puccinia striiformis are important barley pathogens with the potential to cause high yield losses through an epidemic spread. The identification of QTL conferring resistance to these pathogens is the basis for targeted breeding approaches aiming to improve stripe rust and leaf rust resistance of modern cultivars. Exploiting the allelic richness of wild barley accessions proved to be a valuable tool to broaden the genetic base of resistance of barley cultivars. In this study, SNP-based nested association mapping (NAM was performed to map stripe rust and leaf rust resistance QTL in the barley NAM population HEB-25, comprising 1,420 lines derived from BC1S3 generation. By scoring the percentage of infected leaf area, followed by calculation of the area under the disease progress curve and the average ordinate during a two-year field trial, a large variability of resistance across and within HEB-25 families was observed. NAM based on 5,715 informative SNPs resulted in the identification of twelve and eleven robust QTL for resistance against stripe rust and leaf rust, respectively. Out of these, eight QTL for stripe rust and two QTL for leaf rust are considered novel showing no overlap with previously reported resistance QTL. Overall, resistance to both pathogens in HEB-25 is most likely due to the accumulation of numerous small effect loci. In addition, the NAM results indicate that the 25 wild donor QTL alleles present in HEB-25 strongly differ in regard to their individual effect on rust resistance. In future, the NAM concept will allow to select and combine individual wild barley alleles from different HEB parents to increase rust resistance in barley. The HEB-25 results will support to unravel the genetic basis of rust resistance in barley, and to improve resistance against stripe rust and leaf rust of modern barley cultivars.

Resistance to stem rust Ug99 in six bread wheat cultivars maps to chromosome 6DS.

Science.gov (United States)

Lopez-Vera, Eric E; Nelson, Sarah; Singh, Ravi P; Basnet, Bhoja R; Haley, Scott D; Bhavani, Sridhar; Huerta-Espino, Julio; Xoconostle-Cazares, Beatriz G; Ruiz-Medrano, Roberto; Rouse, Matthew N; Singh, Sukhwinder

2014-01-01

Identified SSR markers ( Xcfd49 and Xbarc183 ) linked with stem rust resistance for efficient use in marker-assisted selection and stacking of resistance genes in wheat breeding programs. More than 80 % of the worldwide wheat (Triticum aestivum L.) area is currently sown with varieties susceptible to the Ug99 race group of stem rust fungus. However, wheat lines Niini, Tinkio, Coni, Pfunye, Blouk, and Ripper have demonstrated Ug99 resistance at the seedling and adult plant stages. We mapped stem rust resistance in populations derived from crosses of a susceptible parent with each of the resistant lines. The segregation of resistance in each population indicated the presence of a single gene. The resistance gene in Niini mapped to short arm of chromosome 6D and was flanked by SSR markers Xcfd49 at distances of 3.9 cM proximal and Xbarc183 8.4 cM distal, respectively. The chromosome location of this resistance was validated in three other populations: PBW343/Coni, PBW343/Tinkio, and Cacuke/Pfunye. Resistance initially postulated to be conferred by the SrTmp gene in Blouk and Ripper was also linked to Xcfd49 and Xbarc183 on 6DS, but it was mapped proximal to Xbarc183 at a similar position to previously mapped genes Sr42 and SrCad. Based on the variation in diagnostic marker alleles, it is possible that Niini and Pfunye may carry different resistance genes/alleles. Further studies are needed to determine the allelic relationships between various genes located on chromosome arm 6DS. Our results provide valuable molecular marker and genetic information for developing Ug99 resistant wheat varieties in diverse germplasm and using these markers to tag the resistance genes in wheat breeding.

Transfer of genes for stem rust resistance from Agropyron elongatum and imperial rye to durum wheat

International Nuclear Information System (INIS)

Prabhakara Rao, M.V.

1977-01-01

The Agropyron elongatum gene for stem rust resistance on chromosome 6A of Knott's Thatcher translocation line was transferred to a susceptible local durum wheat variety, Jaya, through a series of back-crosses. Plants heterozygous for the Agropyron translocation always show at least one open bivalent. Homozygotes have not been obtained, probably because of the absence of male transmission in durum background. Monotelosomic addition of the short arm of Imperial rye chromosome 3R (formerly ''G'' of Sears), which carries a gene(s) for resistance to wheat stem rust, was obtained in the local durum variety. Rust-resistant plants from parents having the added rye telocentric were irradiated with gamma rays just before meiosis, and the pollen obtained from the irradiated spikes was used to pollinate euploid plants. In addition, seeds harvested from 2n+1 resistant plants were irradiated with thermal neutrons and the resistant M 1 plants were selfed to raise M 2 families. Two durum-rye translocation lines were obtained following irradiation. DRT-1 was transmitted normally through the female gametes but showed no male transmission. As a result of this, homozygotes have not been obtained. Gametic transmission rates of DRT-2 are being tested. Alien translocations, which show normal gametic and zygotic transmissions in the hexaploid wheat, may behave differently in a tetraploid background. The results indicate that alien genetic transfers may be more difficult to obtain in durum wheat, probably owing to the reduced buffering effect of the tetraploid genome. (author)

A reassessment of the risk of rust fungi developing resistance to fungicides.

Science.gov (United States)

Oliver, Richard P

2014-11-01

Rust fungi are major pathogens of many annual and perennial crops. Crop protection is largely based on genetic and chemical control. Fungicide resistance is a significant issue that has affected many crop pathogens. Some pathogens have rapidly developed resistance and hence are regarded as high-risk species. Rust fungi have been classified as being low risk, in spite of sharing many relevant features with high-risk pathogens. An examination of the evidence suggests that rust fungi may be wrongly classified as low risk. Of the nine classes of fungicide to which resistance has developed, six are inactive against rusts. The three remaining classes are quinone outside inhibitors (QoIs), demethylation inhibitors (DMIs) and succinate dehydrogenase inhibitors (SDHIs). QoIs have been protected by a recently discovered intron that renders resistant mutants unviable. Low levels of resistance have developed to DMIs, but with limited field significance. Older SDHI fungicides were inactive against rusts. Some of the SDHIs introduced since 2003 are active against rusts, so it may be that insufficient time has elapsed for resistance to develop, especially as SDHIs are generally sold in mixtures with other actives. It would therefore seem prudent to increase the level of vigilance for possible cases of resistance to established and new fungicides in rusts. © 2014 Society of Chemical Industry.

Effector proteins of rust fungi.

Science.gov (United States)

Petre, Benjamin; Joly, David L; Duplessis, Sébastien

2014-01-01

Rust fungi include many species that are devastating crop pathogens. To develop resistant plants, a better understanding of rust virulence factors, or effector proteins, is needed. Thus far, only six rust effector proteins have been described: AvrP123, AvrP4, AvrL567, AvrM, RTP1, and PGTAUSPE-10-1. Although some are well established model proteins used to investigate mechanisms of immune receptor activation (avirulence activities) or entry into plant cells, how they work inside host tissues to promote fungal growth remains unknown. The genome sequences of four rust fungi (two Melampsoraceae and two Pucciniaceae) have been analyzed so far. Genome-wide analyses of these species, as well as transcriptomics performed on a broader range of rust fungi, revealed hundreds of small secreted proteins considered as rust candidate secreted effector proteins (CSEPs). The rust community now needs high-throughput approaches (effectoromics) to accelerate effector discovery/characterization and to better understand how they function in planta. However, this task is challenging due to the non-amenability of rust pathosystems (obligate biotrophs infecting crop plants) to traditional molecular genetic approaches mainly due to difficulties in culturing these species in vitro. The use of heterologous approaches should be promoted in the future.

In situ hybridization for the detection of rust fungi in paraffin embedded plant tissue sections.

Science.gov (United States)

Ellison, Mitchell A; McMahon, Michael B; Bonde, Morris R; Palmer, Cristi L; Luster, Douglas G

2016-01-01

Rust fungi are obligate pathogens with multiple life stages often including different spore types and multiple plant hosts. While individual rust pathogens are often associated with specific plants, a wide range of plant species are infected with rust fungi. To study the interactions between these important pathogenic fungi and their host plants, one must be able to differentiate fungal tissue from plant tissue. This can be accomplished using the In situ hybridization (ISH) protocol described here. To validate reproducibility using the ISH protocol, samples of Chrysanthemum × morifolium infected with Puccinia horiana, Gladiolus × hortulanus infected with Uromyces transversalis and Glycine max infected with Phakopsora pachyrhizi were tested alongside uninfected leaf tissue samples. The results of these tests show that this technique clearly distinguishes between rust pathogens and their respective host plant tissues. This ISH protocol is applicable to rust fungi and potentially other plant pathogenic fungi as well. It has been shown here that this protocol can be applied to pathogens from different genera of rust fungi with no background staining of plant tissue. We encourage the use of this protocol for the study of plant pathogenic fungi in paraffin embedded sections of host plant tissue.

Molecular and genetic study of wheat rusts | Le Maitre | African ...

African Journals Online (AJOL)

Puccinia triticina, Puccinia graminis and Puccinia striiformis cause leaf, stem and yellow rust, respectively. Wheat rusts can cause losses as high as 70%. The rusts ability to evolve fungicide resistance has resulted in the use of resistant cultivars as the primary method of control. Breeding resistant cultivars is a long process ...

Mapping of quantitative adult plant field resistance to leaf rust and stripe rust in two European winter wheat populations reveals co-location of three QTL conferring resistance to both rust pathogens.

Science.gov (United States)

Buerstmayr, Maria; Matiasch, Lydia; Mascher, Fabio; Vida, Gyula; Ittu, Marianna; Robert, Olivier; Holdgate, Sarah; Flath, Kerstin; Neumayer, Anton; Buerstmayr, Hermann

2014-09-01

We detected several, most likely novel QTL for adult plant resistance to rusts. Notably three QTL improved resistance to leaf rust and stripe rust simultaneously indicating broad spectrum resistance QTL. The rusts of wheat (Puccinia spp.) are destructive fungal wheat diseases. The deployment of resistant cultivars plays a central role in integrated rust disease management. Durability of resistance would be preferred, but is difficult to analyse. The Austrian winter wheat cultivar Capo was released in the 1989 and grown on a large acreage during more than two decades and maintained a good level of quantitative leaf rust and stripe rust resistance. Two bi-parental mapping populations: Capo × Arina and Capo × Furore were tested in multiple environments for severity of leaf rust and stripe rust at the adult plant stage in replicated field experiments. Quantitative trait loci associated with leaf rust and stripe rust severity were mapped using DArT and SSR markers. Five QTL were detected in multiple environments associated with resistance to leaf rust designated as QLr.ifa-2AL, QLr.ifa-2BL, QLr.ifa-2BS, QLr.ifa-3BS, and QLr.ifa-5BL, and five for resistance to stripe rust QYr.ifa-2AL, QYr.ifa-2BL, QYr.ifa-3AS, QYr.ifa-3BS, and QYr.ifa-5A. For all QTL apart from two (QYr.ifa-3AS, QLr.ifa-5BL) Capo contributed the resistance improving allele. The leaf rust and stripe rust resistance QTL on 2AL, 2BL and 3BS mapped to the same chromosome positions, indicating either closely linked genes or pleiotropic gene action. These three multiple disease resistance QTL (QLr.ifa-2AL/QYr.ifa-2AL, QLr.ifa.2BL/QYr.ifa-2BL, QLr.ifa-3BS/QYr.ifa.3BS) potentially contribute novel resistance sources for stripe rust and leaf rust. The long-lasting resistance of Capo apparently rests upon a combination of several genes. The described germplasm, QTL and markers are applicable for simultaneous resistance improvement against leaf rust and stripe rust.

Genetic diversity of the myrtle rust pathogen (Austropuccinia psidii) in the Americas and Hawaii: Global implications for invasive threat assessments

Science.gov (United States)

J. E. Stewart; A.L. Ross-Davis; R. N. Graҫa; A. C. Alfenas; T. L. Peever; J. W. Hanna; J. Y. Uchida; R. D. Hauff; C. Y. Kadooka; M.-S. Kim; P. G. Cannon; S. Namba; S. Simeto; C. A. Pérez; M. B. Rayamajhi; D.J. Lodge; M. Arguedas; R. Medel-Ortiz; M. A. López-Ramirez; P. Tennant; M. Glen; P. S. Machado; A. R. McTaggart; A. J. Carnegie; N. B. Klopfenstein; M. Cleary

2017-01-01

Since the myrtle rust pathogen (Austropuccinia psidii) was first reported (as Puccinia psidii) in Brazil on guava (Psidium guajava) in 1884, it has been found infecting diverse myrtaceous species. Because A. psidii has recently spread rapidly worldwide with an extensive host range,...

Molecular and cytogenetic characterization of a durum wheat Aegilops speltoides chromosome translocation conferring resistance to stem rust

Science.gov (United States)

Stem rust is a serious disease of wheat that has caused historical epidemics, but it has not been a threat in recent decades in North America due to the eradication of the alternate host and deployment of resistant cultivars. However, the recent emergence of Ug99 (or race TTKS) poses a threat to glo...

Identification and validation of single nucleotide polymorphic markers linked to Ug99 stem rust resistance in spring wheat

Science.gov (United States)

Wheat stem rust (Puccinia graminis f. sp. tritici Eriks. and E. Henn.) is one of the most destructive diseases world-wide. Races belonging to Ug99 (or TTKSK) continue to cause crop losses in East Africa and threaten global wheat production. Developing and deploying wheat varieties with multiple race...

Genome size variation in the pine fusiform rust pathogen Cronartium quercuum f.sp. fusiforme as determined by flow cytometry

Science.gov (United States)

Claire L Anderson; Thomas L Kubisiak; C Dana Nelson; Jason A Smith; John M Davis

2010-01-01

The genome size of the pine fusiform rust pathogen Cronartium quercuum f.sp. fusiforme (Cqf) was determined by flow cytometric analysis of propidium iodide-stained, intact haploid pycniospores with haploid spores of two genetically well characterized fungal species, Sclerotinia sclerotiorum and Puccinia graminis f.sp. tritici, as size standards. The Cqf haploid genome...

Spread, genetic variation and methods for the detection of Puccinia kuehnii, the causal agent of sugarcane orange rust.

Science.gov (United States)

Sugarcane is susceptible to infection by two rust pathogens, Puccinia melanocephala and P. kuehnii, causing brown and orange rust, respectively. Orange rust of sugarcane was first reported in the Western hemisphere in Florida in July 2007. The pathogen was found to be distributed widely throughout t...

Pushing the boundaries of resistance: insights from Brachypodium-rust interactions

OpenAIRE

Figueroa, Melania; Castell-Miller, Claudia V.; Li, Feng; Hulbert, Scot H.; Bradeen, James M.

2015-01-01

The implications of global population growth urge transformation of current food and bioenergy production systems to sustainability. Members of the family Poaceae are of particular importance both in food security and for their applications as biofuel substrates. For centuries, rust fungi have threatened the production of valuable crops such as wheat, barley, oat, and other small grains; similarly, biofuel crops can also be susceptible to these pathogens. Emerging rust pathogenic races with i...

Breeding wheat mutant Longfu 03D51 with resisting stem rust and genetic analyzation of resisting disease and RAPD maker

International Nuclear Information System (INIS)

Sun Yan; Yin Jing; Wang Guangjin; Zhang Hongji; Huang Jinghua; Guo Qiang; Diao Yanling; Liu Dongjun

2007-01-01

Longfu 03D51 was bred using Long 6239 immature embryo as explants through radiation mutagenesis breeding coupled with tissue culture technique. By artificial inoculation and field breeding identified Longfu 03D51 was identified with high resistance to dominant strain 21C 3 CPH, good quality and high yield. Genetic analysis suggested that stem rust was controlled by a single gene. The DNA polymorphism on Longfu 03D51 and its parents were studied by random amplified polymorphic DNA (RAPD), 3 primers out of 60 RAPD primers were found polymorphism between the Longfu 03D51 and its parent Long 6239, and 3 stable polyphymorphic bands amplified in Longfu 03D51 with the size of 380bp, 700bp, 600 bp by random primer E07, E11, E17, respectively. Genetic and RAPD analysis indicated that 3 RAPD primers E07, E11, E17 might be linked to the gene of stem rust resistance. (authors)

Unveiling common responses of Medicago truncatula to appropriate and inappropriate rust species

Science.gov (United States)

Vaz Patto, Maria Carlota; Rubiales, Diego

2014-01-01

Little is known about the nature of effective defense mechanisms in legumes to pathogens of remotely related plant species. Some rust species are among pathogens with broad host range causing dramatic losses in various crop plants. To understand and compare the different host and nonhost resistance (NHR) responses of legume species against rusts, we characterized the reaction of the model legume Medicago truncatula to one appropriate (Uromyces striatus) and two inappropriate (U. viciae-fabae and U. lupinicolus) rusts. We found that similar pre and post-haustorial mechanisms of resistance appear to be operative in M. truncatula against appropriate and inappropriate rust fungus. The appropriate U. striatus germinated better on M. truncatula accessions then the inappropriate U. viciae-fabae and U. lupinicolus, but once germinated, germ tubes of the three rusts had a similar level of success in finding stomata and forming an appressoria over a stoma. However, responses to different inappropriate rust species also showed some specificity, suggesting a combination of non-specific and specific responses underlying this legume NHR to rust fungi. Further genetic and expression analysis studies will contribute to the development of the necessary molecular tools to use the present information on host and NHR mechanisms to breed for broad-spectrum resistance to rust in legume species. PMID:25426128

Unveiling common responses of Medicago truncatula to appropriate and inappropriate rust species

Directory of Open Access Journals (Sweden)

Maria Carlota eVaz Patto

2014-11-01

Full Text Available Little is known about the nature of effective defense mechanisms in legumes to pathogens of remotely related plant species. Some rust species are among pathogens with broad host range causing dramatic losses in various crop plants. To understand and compare the different host and nonhost resistance responses of legume species against rusts, we characterized the reaction of the model legume Medicago truncatula to one appropriate (Uromyces striatus and two inappropriate (U. viciae-fabae and U. lupinicolus rusts. We found that similar pre and post-haustorial mechanisms of resistance appear to be operative in M. truncatula against appropriate and inappropriate rust fungus. The appropriate U. striatus germinated better on M. truncatula accessions then the inappropriate U. viciae-fabae and U. lupinicolus, but once germinated, germ tubes of the three rusts had a similar level of success in finding stomata and forming an appressoria over a stoma. However responses to different inappropriate rust species also showed some specificity, suggesting a combination of non specific and specific responses underlying this legume nonhost resistance to rust fungi. Further genetic and expression analysis studies will contribute to the development of the necessary molecular tools to use the present information on host and nonhost resistance mechanisms to breed for broad-spectrum resistance to rust in legume species.

Discovery of a Novel Stem Rust Resistance Allele in Durum Wheat that Exhibits Differential Reactions to Ug99 Isolates

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Jayaveeramuthu Nirmala

2017-10-01

Full Text Available Wheat stem rust, caused by Puccinia graminis f. sp. tritici Eriks. & E. Henn, can incur yield losses in susceptible cultivars of durum wheat, Triticum turgidum ssp. durum (Desf. Husnot. Although several durum cultivars possess the stem rust resistance gene Sr13, additional genes in durum wheat effective against emerging virulent races have not been described. Durum line 8155-B1 confers resistance against the P. graminis f. sp. tritici race TTKST, the variant race of the Ug99 race group with additional virulence to wheat stem rust resistance gene Sr24. However, 8155-B1 does not confer resistance to the first-described race in the Ug99 race group: TTKSK. We mapped a single gene conferring resistance in 8155-B1 against race TTKST, Sr8155B1, to chromosome arm 6AS by utilizing Rusty/8155-B1 and Rusty*2/8155-B1 populations and the 90K Infinium iSelect Custom bead chip supplemented by KASP assays. One marker, KASP_6AS_IWB10558, cosegregated with Sr8155B1 in both populations and correctly predicted Sr8155B1 presence or absence in 11 durum cultivars tested. We confirmed the presence of Sr8155B1 in cultivar Mountrail by mapping in the population Choteau/Mountrail. The marker developed in this study could be used to predict the presence of resistance to race TTKST in uncharacterized durum breeding lines, and also to combine Sr8155B1 with resistance genes effective to Ug99 such as Sr13. The map location of Sr8155B1 cannot rule out the possibility that this gene is an allele at the Sr8 locus. However, race specificity indicates that Sr8155B1 is different from the known alleles Sr8a and Sr8b.

Rust transformation/rust compatible primers

Science.gov (United States)

Emeric, Dario A.; Miller, Christopher E.

1993-01-01

Proper surface preparation has been the key to obtain good performance by a surface coating. The major obstacle in preparing a corroded or rusted surface is the complete removal of the contaminants and the corrosion products. Sandblasting has been traditionally used to remove the corrosion products before painting. However, sandblasting can be expensive, may be prohibited by local health regulations and is not applicable in every situation. To get around these obstacles, Industry developed rust converters/rust transformers and rust compatible primers (high solids epoxies). The potential use of these products for military equipment led personnel of the Belvoir Research, Development and Engineering Center (BRDEC) to evaluate the commercially available rust transformers and rust compatible primers. Prior laboratory experience with commercially available rust converters, as well as field studies in Hawaii and Puerto Rico, revealed poor performance, several inherent limitations, and lack of reliability. It was obvious from our studies that the performance of rust converting products was more dependent on the amount and type of rust present, as well as the degree of permeability of the coating, than on the product's ability to form an organometallic complex with the rust. Based on these results, it was decided that the Military should develop their own rust converter formulation and specification. The compound described in the specification is for use on a rusted surface before the application of an organic coating (bituminous compounds, primer or topcoat). These coatings should end the need for sandblasting or the removing of the adherent corrosion products. They also will prepare the surface for the application of the organic coating. Several commercially available rust compatible primers (RCP) were also tested using corroded surfaces. All of the evaluated RCP failed our laboratory tests for primers.

Tolerance of Loblolly Pines to Fusiform Rust

Science.gov (United States)

Charles H. Walkinshaw; James P. Barnett

1995-01-01

Loblolly pines (Pinus taeda L.) that were 8 to 17 yr old tolerated one to three fusiform rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme) galls in their stems.Families with four or more galls in their stems lost 2.5% or more of the trees by age 17.In living trees with less than four stem galls, diameter growth was comparable to...

Conserved loci of leaf and stem rust fungi of wheat share synteny interrupted by lineage-specific influx of repeat elements

Directory of Open Access Journals (Sweden)

Fellers John P

2013-01-01

Full Text Available Abstract Background Wheat leaf rust (Puccinia triticina Eriks; Pt and stem rust fungi (P. graminis f.sp. tritici; Pgt are significant economic pathogens having similar host ranges and life cycles, but different alternate hosts. The Pt genome, currently estimated at 135 Mb, is significantly larger than Pgt, at 88 Mb, but the reason for the expansion is unknown. Three genomic loci of Pt conserved proteins were characterized to gain insight into gene content, genome complexity and expansion. Results A bacterial artificial chromosome (BAC library was made from P. triticina race 1, BBBD and probed with Pt homologs of genes encoding two predicted Pgt secreted effectors and a DNA marker mapping to a region of avirulence. Three BACs, 103 Kb, 112 Kb, and 166 Kb, were sequenced, assembled, and open reading frames were identified. Orthologous genes were identified in Pgt and local conservation of gene order (microsynteny was observed. Pairwise protein identities ranged from 26 to 99%. One Pt BAC, containing a RAD18 ortholog, shares syntenic regions with two Pgt scaffolds, which could represent both haplotypes of Pgt. Gene sequence is diverged between the species as well as within the two haplotypes. In all three BAC clones, gene order is locally conserved, however, gene shuffling has occurred relative to Pgt. These regions are further diverged by differing insertion loci of LTR-retrotransposon, Gypsy, Copia, Mutator, and Harbinger mobile elements. Uncharacterized Pt open reading frames were also found; these proteins are high in lysine and similar to multiple proteins in Pgt. Conclusions The three Pt loci are conserved in gene order, with a range of gene sequence divergence. Conservation of predicted haustoria expressed secreted protein genes between Pt and Pgt is extended to the more distant poplar rust, Melampsora larici-populina. The loci also reveal that genome expansion in Pt is in part due to higher occurrence of repeat-elements in this species.

Investigating Gene Function in Cereal Rust Fungi by Plant-Mediated Virus-Induced Gene Silencing.

Science.gov (United States)

Panwar, Vinay; Bakkeren, Guus

2017-01-01

Cereal rust fungi are destructive pathogens, threatening grain production worldwide. Targeted breeding for resistance utilizing host resistance genes has been effective. However, breakdown of resistance occurs frequently and continued efforts are needed to understand how these fungi overcome resistance and to expand the range of available resistance genes. Whole genome sequencing, transcriptomic and proteomic studies followed by genome-wide computational and comparative analyses have identified large repertoire of genes in rust fungi among which are candidates predicted to code for pathogenicity and virulence factors. Some of these genes represent defence triggering avirulence effectors. However, functions of most genes still needs to be assessed to understand the biology of these obligate biotrophic pathogens. Since genetic manipulations such as gene deletion and genetic transformation are not yet feasible in rust fungi, performing functional gene studies is challenging. Recently, Host-induced gene silencing (HIGS) has emerged as a useful tool to characterize gene function in rust fungi while infecting and growing in host plants. We utilized Barley stripe mosaic virus-mediated virus induced gene silencing (BSMV-VIGS) to induce HIGS of candidate rust fungal genes in the wheat host to determine their role in plant-fungal interactions. Here, we describe the methods for using BSMV-VIGS in wheat for functional genomics study in cereal rust fungi.

Characterization of Brachypodium distachyon as a nonhost model against switchgrass rust pathogen Puccinia emaculata.

Science.gov (United States)

Gill, Upinder S; Uppalapati, Srinivasa R; Nakashima, Jin; Mysore, Kirankumar S

2015-05-08

Switchgrass rust, caused by Puccinia emaculata, is an important disease of switchgrass, a potential biofuel crop in the United States. In severe cases, switchgrass rust has the potential to significantly affect biomass yield. In an effort to identify novel sources of resistance against switchgrass rust, we explored nonhost resistance against P. emaculata by characterizing its interactions with six monocot nonhost plant species. We also studied the genetic variations for resistance among Brachypodium inbred accessions and the involvement of various defense pathways in nonhost resistance of Brachypodium. We characterized P. emaculata interactions with six monocot nonhost species and identified Brachypodium distachyon (Bd21) as a suitable nonhost model to study switchgrass rust. Interestingly, screening of Brachypodium accessions identified natural variations in resistance to switchgrass rust. Brachypodium inbred accessions Bd3-1 and Bd30-1 were identified as most and least resistant to switchgrass rust, respectively, when compared to tested accessions. Transcript profiling of defense-related genes indicated that the genes which were induced in Bd21after P. emaculata inoculation also had higher basal transcript abundance in Bd3-1 when compared to Bd30-1 and Bd21 indicating their potential involvement in nonhost resistance against switchgrass rust. In the present study, we identified Brachypodium as a suitable nonhost model to study switchgrass rust which exhibit type I nonhost resistance. Variations in resistance response were also observed among tested Brachypodium accessions. Brachypodium nonhost resistance against P. emaculata may involve various defense pathways as indicated by transcript profiling of defense related genes. Overall, this study provides a new avenue to utilize novel sources of nonhost resistance in Brachypodium against switchgrass rust.

Pushing the boundaries of resistance: insights from Brachypodium-rust interactions

Directory of Open Access Journals (Sweden)

Melania eFigueroa

2015-07-01

Full Text Available The implications of global population growth urge transformation of current food and bioenergy production systems to sustainability. Members of the family Poaceae are of particular importance both in food security and for their applications as biofuel substrates. For centuries, rust fungi have threatened the production of valuable crops such as wheat, barley, oat and other small grains; similarly, biofuel crops can also be susceptible to these pathogens. Emerging rust pathogenic races with increased virulence and recurrent rust epidemics around the world point out the vulnerability of monocultures. Basic research in plant immunity, especially in model plants, can make contributions to understanding plant resistance mechanisms and improve disease management strategies. The development of the grass Brachypodium distachyon as a genetically tractable model for monocots, especially temperate cereals and grasses, offers the possibility to overcome the experimental challenges presented by the genetic and genomic complexities of economically valuable crop plants. The numerous resources and tools available in Brachypodium have opened new doors to investigate the underlying molecular and genetic bases of plant-microbe interactions in grasses and evidence demonstrating the applicability and advantages of working with B. distachyon is increasing. Importantly, several interactions between B. distachyon and devastating plant pathogens, such rust fungi, have been examined in the context of non-host resistance. Here, we discuss the use of B. distachyon in these various pathosystems. Exploiting B. distachyon to understand the mechanisms underpinning disease resistance to non-adapted rust fungi may provide effective and durable approaches to fend off these pathogens. The close phylogenetic relationship among Brachypodium spp. and grasses with industrial and agronomic value support harnessing this model plant to improve cropping systems and encourage its use in

Identification and characterization of Sr13, a tetraploid wheat gene that confers resistance to the Ug99 stem rust race group

Science.gov (United States)

The Puccinia graminis f. sp. tritici (Pgt) Ug99 race group is virulent to most stem rust resistance genes currently deployed in wheat and poses a serious threat to global wheat production. The durum wheat (Triticum turgidum ssp. durum) gene Sr13 confers resistance to Ug99 in addition to virulent rac...

Genome-wide association study for Identification and validation of novel SNP markers for Sr6 stem rust resistance gene in bread wheat

Science.gov (United States)

Stem rust (caused by Puccinia graminis f. sp. tritici Erikss. & E. Henn.), is a major disease in wheat (Triticum aestivium L.). However, in recent years it occurs rarely in Nebraska due to weather and the effective selection and gene pyramiding of resistance genes. To understand the genetic basis of...

Molecular and genetic study of wheat rusts

African Journals Online (AJOL)

Nicholas Le Maitre

Phylogenetic trees were created for leaf and stem rust pathotypes. Field isolates of ... Key words: Prevalence, microsatellite, amplified fragment length polymorphisms (AFLP), phylogeny, Puccinia. INTRODUCTION. Puccinia triticina Eriks ..... Genetic distances and reconstruction phylogenetic trees from microsatellite DNA.

Leaf rust of cultivated barley: pathology and control.

Science.gov (United States)

Park, Robert F; Golegaonkar, Prashant G; Derevnina, Lida; Sandhu, Karanjeet S; Karaoglu, Haydar; Elmansour, Huda M; Dracatos, Peter M; Singh, Davinder

2015-01-01

Leaf rust of barley is caused by the macrocyclic, heteroecious rust pathogen Puccinia hordei, with aecia reported from selected species of the genera Ornithogalum, Leopoldia, and Dipcadi, and uredinia and telia occurring on Hordeum vulgare, H. vulgare ssp. spontaneum, Hordeum bulbosum, and Hordeum murinum, on which distinct parasitic specialization occurs. Although Puccinia hordei is sporadic in its occurrence, it is probably the most common and widely distributed rust disease of barley. Leaf rust has increased in importance in recent decades in temperate barley-growing regions, presumably because of more intensive agricultural practices. Although total crop loss does not occur, under epidemic conditions yield reductions of up to 62% have been reported in susceptible varieties. Leaf rust is primarily controlled by the use of resistant cultivars, and, to date, 21 seedling resistance genes and two adult plant resistance (APR) genes have been identified. Virulence has been detected for most seedling resistance genes but is unknown for the APR genes Rph20 and Rph23. Other potentially new sources of APR have been reported, and additivity has been described for some of these resistances. Approaches to achieving durable resistance to leaf rust in barley are discussed.

Detection, breeding, and selection of durable resistance to brown rust in sugarcane

Science.gov (United States)

Brown rust, caused by Puccinia melanocephala, is an important disease of sugarcane in Louisiana. The adaptability of the pathogen has repeatedly resulted in resistant cultivars becoming susceptible once they are widely grown. The frequency of the brown rust resistance gene Bru1 was low in the breedi...

Reaction of Rust on Some Bread Wheat Varieties in Çukurova Region

OpenAIRE

AY, Hasan

2013-01-01

This study was conducted with 126 varieties of wheat between 2009-2010 years in Adana. There has not been artificially inoculated yellow, leaf and stem rusts. Races of rust in natural were evaluated in both years. Between 2009-2010 this study was conducted in Adana, with 126 varieties of bread wheat. In both years, only the natural environment leaf rust races inoculated for assessments reactions of bread wheat. According to results, 49 bread wheat varieties were found resistant, 6 bread wheat...

Identification of nine pathotype-specific genes conferring resistance to fusiform rust in loblolly pine (Pinus taeda L.)

Science.gov (United States)

Henry Amerson; C. Dana Nelson; Thomas L. Kubisiak; E.George Kuhlman; Saul Garcia

2015-01-01

Nearly two decades of research on the host-pathogen interaction in fusiform rust of loblolly pine is detailed. Results clearly indicate that pathotype-specific genes in the host interacting with pathogen avirulence cause resistance as defined by the non-gall phenotype under favorable environmental conditions for disease development. In particular, nine fusiform rust...

Introgression of leaf rust and stripe rust resistance from Sharon goatgrass (Aegilops sharonensis Eig) into bread wheat (Triticum aestivum L.).

Science.gov (United States)

Millet, E; Manisterski, J; Ben-Yehuda, P; Distelfeld, A; Deek, J; Wan, A; Chen, X; Steffenson, B J

2014-06-01

Leaf rust and stripe rust are devastating wheat diseases, causing significant yield losses in many regions of the world. The use of resistant varieties is the most efficient way to protect wheat crops from these diseases. Sharon goatgrass (Aegilops sharonensis or AES), which is a diploid wild relative of wheat, exhibits a high frequency of leaf and stripe rust resistance. We used the resistant AES accession TH548 and induced homoeologous recombination by the ph1b allele to obtain resistant wheat recombinant lines carrying AES chromosome segments in the genetic background of the spring wheat cultivar Galil. The gametocidal effect from AES was overcome by using an "anti-gametocidal" wheat mutant. These recombinant lines were found resistant to highly virulent races of the leaf and stripe rust pathogens in Israel and the United States. Molecular DArT analysis of the different recombinant lines revealed different lengths of AES segments on wheat chromosome 6B, which indicates the location of both resistance genes.

Fusiform Rust of Southern Pines

Science.gov (United States)

W. R. Phelps; F. L. Czabator

1978-01-01

Fusiform rust, caused by the fungus Cronartium fusiforme Hedg. & Hunt ex Cumm., is distributed in the Southern United States from Maryland to Florida and west to Texas and southern Arkansas. Infections by the fungus, which develops at or near the point of infection, result in tapered, spindle-shaped swells, called galls, on branches and stems of pines. (see photo...

A novel Robertsonian translocation event leads to transfer of a stem rust resistance gene (Sr52) effective against race Ug99 from Dasypyrum villosum into bread wheat.

Science.gov (United States)

Qi, L L; Pumphrey, M O; Friebe, Bernd; Zhang, P; Qian, C; Bowden, R L; Rouse, M N; Jin, Y; Gill, B S

2011-06-01

Stem rust (Puccinia graminis f. sp. tritici Eriks. & E. Henn.) (the causal agent of wheat stem rust) race Ug99 (also designated TTKSK) and its derivatives have defeated several important stem rust resistance genes widely used in wheat (Triticum aestivum L.) production, rendering much of the worldwide wheat acreage susceptible. In order to identify new resistance sources, a large collection of wheat relatives and genetic stocks maintained at the Wheat Genetic and Genomic Resources Center was screened. The results revealed that most accessions of the diploid relative Dasypyrum villosum (L.) Candargy were highly resistant. The screening of a set of wheat-D. villosum chromosome addition lines revealed that the wheat-D. villosum disomic addition line DA6V#3 was moderately resistant to race Ug99. The objective of the present study was to produce and characterize compensating wheat-D. villosum whole arm Robertsonian translocations (RobTs) involving chromosomes 6D of wheat and 6V#3 of D. villosum through the mechanism of centric breakage-fusion. Seven 6V#3-specific EST-STS markers were developed for screening F(2) progeny derived from plants double-monosomic for chromosomes 6D and 6V#3. Surprisingly, although 6D was the target chromosome, all recovered RobTs involved chromosome 6A implying a novel mechanism for the origin of RobTs. Homozygous translocations (T6AS·6V#3L and T6AL·6V#3S) with good plant vigor and full fertility were selected from F(3) families. A stem rust resistance gene was mapped to the long arm 6V#3L in T6AS·6V#3L and was designated as Sr52. Sr52 is temperature-sensitive and is most effective at 16°C, partially effective at 24°C, and ineffective at 28°C. The T6AS·6V#3L stock is a new source of resistance to Ug99, is cytogenetically stable, and may be useful in wheat improvement.

Marker-assisted pyramiding of Thinopyrumderived leaf rust ...

Indian Academy of Sciences (India)

2017-03-20

Mar 20, 2017 ... resistance genes Lr19 and Lr24 using marker assisted foreground .... is linked with stem rust resistance gene Sr24(McIntosh et al. 1976). .... Received 29 July 2016, in final revised form 3 March 2017; accepted 16 March 2017.

Identification of Putative Coffee Rust Mycoparasites via Single-Molecule DNA Sequencing of Infected Pustules.

Science.gov (United States)

James, Timothy Y; Marino, John A; Perfecto, Ivette; Vandermeer, John

2016-01-15

The interaction of crop pests with their natural enemies is a fundament to their control. Natural enemies of fungal pathogens of crops are poorly known relative to those of insect pests, despite the diversity of fungal pathogens and their economic importance. Currently, many regions across Latin America are experiencing unprecedented epidemics of coffee rust (Hemileia vastatrix). Identification of natural enemies of coffee rust could aid in developing management strategies or in pinpointing species that could be used for biocontrol. In the present study, we characterized fungal communities associated with coffee rust lesions by single-molecule DNA sequencing of fungal rRNA gene bar codes from leaf discs (≈28 mm(2)) containing rust lesions and control discs with no rust lesions. The leaf disc communities were hyperdiverse in terms of fungi, with up to 69 operational taxonomic units (putative species) per control disc, and the diversity was only slightly reduced in rust-infected discs, with up to 63 putative species. However, geography had a greater influence on the fungal community than whether the disc was infected by coffee rust. Through comparisons between control and rust-infected leaf discs, as well as taxonomic criteria, we identified 15 putative mycoparasitic fungi. These fungi are concentrated in the fungal family Cordycipitaceae and the order Tremellales. These data emphasize the complexity of diverse fungi of unknown ecological function within a leaf that might influence plant disease epidemics or lead to the development of species for biocontrol of fungal disease. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Current and future molecular approaches to investigate the white pine blister rust pathosystem

Science.gov (United States)

B. A. Richardson; A. K. M. Ekramoddoulah; J.-J. Liu; M.-S. Kim; N. B. Klopfenstein

2010-01-01

Molecular genetics is proving to be especially useful for addressing a wide variety of research and management questions on the white pine blister rust pathosystem. White pine blister rust, caused by Cronartium ribicola, is an ideal model for studying biogeography, genetics, and evolution because: (1) it involves an introduced pathogen; (2) it includes multiple primary...

White pine blister rust resistance in limber pine: Evidence for a major gene

Science.gov (United States)

A. W. Schoettle; R. A. Sniezko; A. Kegley; K. S. Burns

2014-01-01

Limber pine (Pinus flexilis) is being threatened by the lethal disease white pine blister rust caused by the non-native pathogen Cronartium ribicola. The types and frequencies of genetic resistance to the rust will likely determine the potential success of restoration or proactive measures. These first extensive inoculation trials using individual tree seed collections...

Host status of false brome grass to the leaf rust fungus Puccinia brachypodii and the stripe rust fungus P. Striiformis

NARCIS (Netherlands)

Barbieri, M.; Marcel, T.C.; Niks, R.E.

2011-01-01

Purple false brome grass (Brachypodium distachyon) has recently emerged as a model system for temperate grasses and is also a potential model plant to investigate plant interactions with economically important pathogens such as rust fungi. We determined the host status of five Brachypodium species

Expression of apoplast-targeted plant defensin MtDef4.2 confers resistance to leaf rust pathogen Puccinia triticina but does not affect mycorrhizal symbiosis in transgenic wheat.

Science.gov (United States)

Kaur, Jagdeep; Fellers, John; Adholeya, Alok; Velivelli, Siva L S; El-Mounadi, Kaoutar; Nersesian, Natalya; Clemente, Thomas; Shah, Dilip

2017-02-01

Rust fungi of the order Pucciniales are destructive pathogens of wheat worldwide. Leaf rust caused by the obligate, biotrophic basidiomycete fungus Puccinia triticina (Pt) is an economically important disease capable of causing up to 50 % yield losses. Historically, resistant wheat cultivars have been used to control leaf rust, but genetic resistance is ephemeral and breaks down with the emergence of new virulent Pt races. There is a need to develop alternative measures for control of leaf rust in wheat. Development of transgenic wheat expressing an antifungal defensin offers a promising approach to complement the endogenous resistance genes within the wheat germplasm for durable resistance to Pt. To that end, two different wheat genotypes, Bobwhite and Xin Chun 9 were transformed with a chimeric gene encoding an apoplast-targeted antifungal plant defensin MtDEF4.2 from Medicago truncatula. Transgenic lines from four independent events were further characterized. Homozygous transgenic wheat lines expressing MtDEF4.2 displayed resistance to Pt race MCPSS relative to the non-transgenic controls in growth chamber bioassays. Histopathological analysis suggested the presence of both pre- and posthaustorial resistance to leaf rust in these transgenic lines. MtDEF4.2 did not, however, affect the root colonization of a beneficial arbuscular mycorrhizal fungus Rhizophagus irregularis. This study demonstrates that the expression of apoplast-targeted plant defensin MtDEF4.2 can provide substantial resistance to an economically important leaf rust disease in transgenic wheat without negatively impacting its symbiotic relationship with the beneficial mycorrhizal fungus.

Climate change impacts on coffee rust disease

Science.gov (United States)

Alfonsi, W. M. V.; Koga-Vicente, A.; Pinto, H. S.; Alfonsi, E. L., Sr.; Coltri, P. P.; Zullo, J., Jr.; Patricio, F. R.; Avila, A. M. H. D.; Gonçalves, R. R. D. V.

2016-12-01

Changes in climate conditions and in extreme weather events may affect the food security due to impacts in agricultural production. Despite several researches have been assessed the impacts of extremes in yield crops in climate change scenarios, there is the need to consider the effects in pests and diseases which increase losses in the sector. Coffee Arabica is an important commodity in world and plays a key role in Brazilian agricultural exports. Although the coffee crop has a world highlight, its yield is affected by several factors abiotic or biotic. The weather as well pests and diseases directly influence the development and coffee crop yield. These problems may cause serious damage with significant economic impacts. The coffee rust, caused by the fungus Hemileia vastarix,is among the diseases of greatest impact for the crop. The disease emerged in Brazil in the 70s and is widely spread in all producing regions of coffee in Brazil, and in the world. Regions with favorable weather conditions for the pathogen may exhibit losses ranging from 30% to 50% of the total grain production. The evaluation of extreme weather events of coffee rust disease in futures scenarios was carried out using the climatic data from CMIP5 models, data field of coffee rust disease incidence and, incubation period simulation data for Brazilian municipalities. Two Regional Climate Models were selected, Eta-HadGEM2-ES and Eta-MIROC5, and the Representative Concentration Pathways 8.5 w/m2 was adopted. The outcomes pointed out that in these scenarios the period of incubation tends to decrease affecting the coffee rust disease incidence, which tends to increase. Nevertheless, the changing in average trends tends to benefit the reproduction of the pathogen. Once the temperature threshold for the disease reaches the adverse conditions it may be unfavorable for the incidence.

REVIEW - Advances on molecular studies of the interaction soybean - Asian rust

Directory of Open Access Journals (Sweden)

Aguida Maria Alves Pereira Morales

2012-01-01

Full Text Available Effective management practices are essential for controlling rust outbreaks. The main control methodused is the application of fungicides, which increases substantially the cost of production and is harmful to theenvironment. Prevention is still the best way to avoid more significant losses in soybean yields. Alternatives,such as planting resistant varieties to the fungus, are also important. The use of resistant or tolerant varietiesis the most promising method for controlling Asian soybean rust. Recently, five dominant genes resistant to soybean rust were described: Rpp1, Rpp2, Rpp3, Rpp4 and Rpp5. However, little is known about the molecular interaction among soybean plant and soybean rust and on the molecular pathway triggered by pathogen recognition. Understanding the molecular mechanisms involved in defense responses is of primary importance for planning strategies to control stress and, consequently, to increase plant adaptation to limiting conditions

Barberry rust survey – developing tools for diagnosis, analysis and data management

DEFF Research Database (Denmark)

Justesen, Annemarie Fejer; Hansen, Jens Grønbech; Hovmøller, Mogens Støvring

Barberry (Berberis spp.) may serve as alternate host of several Puccinia species including Puccinia graminis and P. striiformis causing stem and yellow rust on cereals and grasses, respectively. In order to study the importance of barberry in the epidemiology of Puccinia species in the CWANA regi...... a rust survey was initiated. The aim was to 1) develop a surveillance protocol 2) develop molecular diagnostic tools for identifying Puccinia spp. from aecial samples, and 3) develop a data management and display system of results as part of the Wheat Rust ToolBox (http....... Due to variable quality of aecial samples DNA extraction was not successful for 40% of the samples. Sequences of EF1α, β-tubulin or ITS were analysed and compared to reference sequences of rust fungi infecting cereals and grasses. The analysis supported the presence of P. graminis s.l., P....... arrhenatheri and P. striiformoides on barberry species. Survey and DNA sample maps with species designation were displayed in the Wheat Rust ToolBox. The future aim is to integrate barberry rust survey data based on molecular diagnostics and infection assays from research groups world-wide in order to gain...

Emergence of virulence to SrTmp in the Ug99 race group of wheat stem rust, Puccinia graminis f. sp. tritici, in Africa

DEFF Research Database (Denmark)

Patpour, M.; Hovmøller, M. S.; Justesen, A. F.

2016-01-01

of wheat fields in Africa (Kenya, 9; Uganda, 28; Rwanda, 41; and Egypt, 6) were sent to the Global Rust Reference Center (GRRC, Denmark) for race analysis. Puccinia graminis f. sp. tritici (Pgt) samples were recovered on cv. Morocco, and resulting urediniospores of 53 single-pustule isolates were......Tmp) to confirm their virulence/avirulence combinations to Sr24, Sr31, Sr36, and SrTmp. Race TTKTK was also detected at two locations in Uganda (Rubaya and Muko in Kabale region) and at five locations in Rwanda (Kinigi, Rwerere, Rufungo, Gatebe, and Kamenyo). Three isolates derived from stem rust samples...

Dehydro-alpha-lapachone isolated from Catalpa ovata stems: activity against plant pathogenic fungi.

Science.gov (United States)

Cho, Jun Young; Kim, Hae Young; Choi, Gyung Ja; Jang, Kyoung Soo; Lim, He Kyoung; Lim, Chi Hwan; Cho, Kwang Yun; Kim, Jin-Cheol

2006-05-01

The methanol extract of stems of Catalpa ovata G Don exhibits potent in vivo antifungal activity against Magnaporthe grisea (Hebert) Barr (rice blast) on rice plants, Botrytis cinerea Pers ex Fr (tomato grey mould) and Phytophthora infestans (Mont) de Bary (tomato late blight) on tomato plants, Puccinia recondita Rob ex Desm (wheat leaf rust) on wheat plants and Blumeria graminis (DC) Speer f. sp. hordei Marchal (barley powdery mildew) on barley plants. An antifungal substance was isolated and identified as dehydro-alpha-lapachone from mass and nuclear magnetic resonance spectral data. It completely inhibited the mycelial growth of B. cinerea, Colletotrichum acutatum Simmonds, Colletotrichum gloeosporioides Simmonds, M. grisea and Pythium ultimum Trow over a range of 0.4-33.3 mg litre(-1). It also controlled the development of rice blast, tomato late blight, wheat leaf rust, barley powdery mildew and red pepper anthracnose (Colletotrichum coccodes (Wallr) S Hughes). The chemical was particularly effective in suppressing red pepper anthracnose by 95% at a concentration of 125 mg litre(-1). Copyright 2006 Society of Chemical Industry.

Tagging and mapping of SSR marker for rust resistance gene in lentil (Lens culinaris Medikus subsp. culinaris).

Science.gov (United States)

Dikshit, H K; Singh, Akanksha; Singh, D; Aski, M; Jain, Neelu; Hegde, V S; Basandrai, A K; Basandrai, D; Sharma, T R

2016-06-01

Lentil, as an economical source of protein, minerals and vitamins, plays important role in nutritional security of the common man. Grown mainly in West Asia, North Africa (WANA) region and South Asia, it suffers from several biotic stresses such as wilt, rust, blight and broomrape. Lentil rust caused by autoecious fungus Uromyces viciae fabae (Pers.) Schroet is a serious lentil disease in Algeria, Bangladesh, Ethiopia, India, Italy, Morocco, Pakistan and Nepal. The disease symptoms are observed during flowering and early podding stages. Rust causes severe yield losses in lentil. It can only be effectively controlled by identifying the resistant source, understanding its inheritance and breeding for host resistance. The obligate parasitic nature of pathogen makes it difficult to maintain the pathogen in culture and to apply it to screen segregating progenies under controlled growth conditions. Hence, the use of molecular markers will compliment in identification of resistant types in different breeding programs. Here, we studied the inheritance of resistance to rust in lentil using F₁, F₂ and F₂:₃ from cross PL 8 (susceptible) x L 4149 (resistant) varieties. The phenotyping of lentil population was carried out at Sirmour, India. The result of genetic analysis revealed that a single dominant gene controls rust resistance in lentil genotype L 4149. The F2 population from this cross was used to tag and map the rust resistance gene using SSR and SRAP markers. Markers such as 270 SRAP and 162 SSR were studied for polymorphism and 101 SRAP and 33 SSRs were found to be polymorphic between the parents. Two SRAP and two SSR markers differentiated the resistant and susceptible bulks. SSR marker Gllc 527 was estimated to be linked to rust resistant locus at a distance of 5.9 cM. The Gllc 527 marker can be used for marker assisted selection for rust resistance; however, additional markers closer to rust resistant locus are required. The markers linked to the rust

Antibiotic Treatment of Blister Rust Cankers in Eastern White Pine

Science.gov (United States)

William R. Phelps; Ray Weber

1970-01-01

Cycloheximide (Acti-dione) and Phytoactin antibiotics, applied as basal stem treatments, aerial spray treatments, and complete foliar drenches were not effective in controlling blister rust cankers in eastern white pine. Cycloheximide was effective in suppressing canker activity and growth if directly applied to scarified cankers.

Improvement of resistance to rust through recurrent selection in pearl millet

Energy Technology Data Exchange (ETDEWEB)

Tapsoba, H. [Univ. of Georgia, Athens, GA (United States); Wilson, J.P.; Hanna, W.W. [Univ. of Georgia Coastal Plain Experimental Station, Tifton, GA (United States)

1997-04-01

Two pearl millet [Pennisetum glaucum (L.) R.Br. = P. typhoides (Burm.) Staff & Hubb., P. americanum (L.) K. Schum.] bulk populations, Tift No. 2 and Tift No. 5, served as base populations for four cycles of recurrent selection against susceptibility to Puccinia substriata Ell. & Barth, var. indica Ramachar & Cumm. A bulk inoculum of the pathogen was used. The objectives were to evaluate the progress achieved regarding overall resistance to the pathogen in the field and resistance to different races of the pathogen, and also to evaluate changes in unselected traits. During selection, the frequency of rust resistant plants continuously increased from about 30% in each base population to more than 85% by the third cycle of selection in both populations. An average increase of about 21 and 18% per cycle was obtained in Tift No. 2 and Tift No. 5, respectively. A continuous increase of the frequency of plants resistant to some races of the pathogen was also obtained. In Tift No. 5, 80% of the plants were resistant to eight races by the third cycle of selection. The accumulation of resistance observed in the seedlings was manifested in the field, both in 1993 and 1994, by a reduction of the final rust severity from the base population to the fourth selection cycle of both populations. This improvement in resistance to the rust pathogen was accompanied by an increase in the frequency of plants resistant to Pyricularia grisea (Cooke) Sacc. only in Tift No. 2. Despite the improvement in the selected character, genetic variability for agronomic traits such as plant height, number of culms/plant, flowering date, and panicle length was successfully maintained within each population. 20 refs., 1 fig., 7 tabs.

Sustracted library obtained from mutant sugarcane variety B 4362 resistant to rust

OpenAIRE

María I. Oloriz; Luis Rojas; Víctor Gil; Elio Jiménez

2002-01-01

The hypersensitive response is one of the most powerful mechanisms for which the plants resist pathogen attack. Mutations carried out previously on the variety B4362, of sugarcane, originated five mutants that express this mechanism towards the attack of rust (Puccinia melanocephala Syd.). By means of a subtractive hybridization among the cDNA obtained starting from the resistant clone inoculated with rust and a pool of cDNA of the susceptible variety (B4362) inoculated and of the resistant c...

Protecting steel from rusting by rust. The mechanism of rust formation and its control

International Nuclear Information System (INIS)

Kimura, Masao

2008-01-01

Weathering steel, when exposed outdoors for a few years, forms a protective layer resulting in reduction of the corrosion rate. The state of rusts is fundamental for understanding its mechanisms, but the structure and its relationship with the mechanism have not been understood. In this study, a new crystallographic approach was applied to reveal nano-structure of rusts with using of X-ray synchrotron radiation. It has been shown that additional elements alter the corrosion process in its early stage, resulting in formation of protective rusts. (author)

Characterization of mild steel pre rusted and rust converted surfaces through advanced electrochemical analysis

International Nuclear Information System (INIS)

Riaz, F.; Rizvi, Z.H.; Arshad, K.

2008-01-01

The present work evaluates the anti corrosive properties of a tannin based rust converter applied on the pre rusted steel coupons as compared with the grit blasted bare metal and pre rusted steel coupons. The mechanism and the corrosion control behaviour of the rust converter are characterized and monitored using EIS technique. The result suggested that when the tannin based rust converter applied on the pre rusted/corroded coupon, the protection properties of the mild steel coupon clearly improved because of the more compact conversion layer being formed on the coupon. It is inferred that the rust converter can be applied on the pre rusted samples as an alternative technique to the surface preparation for protection purpose. (author)

A mutagenesis-derived broad-spectrum disease resistance locus in wheat

Science.gov (United States)

Wheat leaf rust, stem rust, stripe rust, and powdery mildew caused by the fungal pathogens Puccinia triticina, P. graminis f. sp. tritici, P. striiformis f. sp. tritici, and Blumeria graminis f. sp. tritici, respectively, are destructive diseases of wheat worldwide. The most effective and widely uti...

McGISH identification and phenotypic description of leaf rust and yellow rust resistant partial amphiploids originating from a wheat × Thinopyrum synthetic hybrid cross.

Science.gov (United States)

Kruppa, Klaudia; Türkösi, Edina; Mayer, Marianna; Tóth, Viola; Vida, Gyula; Szakács, Éva; Molnár-Láng, Márta

2016-11-01

A Thinopyrum intermedium × Thinopyrum ponticum synthetic hybrid wheatgrass is an excellent source of leaf and stem rust resistance produced by N.V.Tsitsin. Wheat line Mv9kr1 was crossed with this hybrid (Agropyron glael) in Hungary in order to transfer its advantageous agronomic traits into wheat. As the wheat parent was susceptible to leaf rust, the transfer of resistance was easily recognizable in the progenies. Three different partial amphiploid lines with leaf rust resistance were selected from the wheat/Thinopyrum hybrid derivatives by multicolour genomic in situ hybridization. Chromosome counting on the partial amphiploids revealed 58 chromosomes (18 wheatgrass) in line 194, 56 (14 wheatgrass) in line 195 and 54 (12 wheatgrass) in line 196. The wheat chromosomes present in these lines were identified and the wheatgrass chromosomes were characterized by fluorescence in situ hybridization using the repetitive DNA probes Afa-family, pSc119.2 and pTa71. The 3D wheat chromosome was missing from the lines. Molecular marker analysis showed the presence of the Lr24 leaf rust resistance gene in lines 195 and 196. The morphological traits were evaluated in the field during two consecutive seasons in two different locations.

QTL mapping provides evidence for lack of association of the avoidance of leaf rust in Hordeum chilense with stomata density

NARCIS (Netherlands)

Vaz Patto, M.C.; Rubiales, D.; Martin, A.; Hernandez, P.; Lindhout, W.H.; Niks, R.E.; Stam, P.

2003-01-01

In cereals, rust fungi are among the most harmful pathogens. Breeders usually rely on short-lived hypersensitivity resistance. As an alternative, "avoidance" may be a more durable defence mechanism to protect plants to rust fungi. In Hordeum chilense avoidance is based on extensive wax covering of

White pine blister rust resistance of 12 western white pine families at three field sites in the Pacific Northwest

Science.gov (United States)

Richard A. Sniezko; Robert Danchok; Jim Hamlin; Angelia Kegley; Sally Long; James Mayo

2012-01-01

Western white pine (Pinus monticola Douglas ex D. Don) is highly susceptible to the non-native, invasive pathogen Cronartium ribicola, the causative agent of white pine blister rust. The susceptibility of western white pine to blister rust has limited its use in restoration and reforestation throughout much of western North...

Sustracted library obtained from mutant sugarcane variety B 4362 resistant to rust

Directory of Open Access Journals (Sweden)

María I. Oloriz

2002-07-01

Full Text Available The hypersensitive response is one of the most powerful mechanisms for which the plants resist pathogen attack. Mutations carried out previously on the variety B4362, of sugarcane, originated five mutants that express this mechanism towards the attack of rust (Puccinia melanocephala Syd.. By means of a subtractive hybridization among the cDNA obtained starting from the resistant clone inoculated with rust and a pool of cDNA of the susceptible variety (B4362 inoculated and of the resistant clone not inoculated, it was possible to reduce the number of genes expressed during the infection with the fungus. A subtractive library was carried out where we hope that most of the genes are involved in the hypersensitive response that present these mutants towards the infection of the pathogen. Key words: Subtractive hybridization, hypersensitive response, Puccinia melanocephala Syd.

Obligate Biotrophy Features Unraveled by the Genomic Analysis of the Rust Fungi, Melampsora larici-populina and Puccinia graminis f. sp. tritici

Energy Technology Data Exchange (ETDEWEB)

Duplessis, Sebastien; Cuomo, Christina A.; Lin, Yao-Cheng; Aerts, Andrea; Tisserant, Emilie; Veneault-Fourrey, Claire; Joly, David L.; Hacquard, Stephane; Amselem, Joelle; Cantarel, Brandi; Chiu, Readman; Couthinho, Pedro; Feau, Nicolas; Field, Matthew; Frey, Pascal; Gelhaye, Eric; Goldberg, Jonathan; Grabherr, Manfred; Kodira, Chinnappa; Kohler, Annegret; Kues, Ursula; Lindquist, Erika; Lucas, Susan; Mago, Rohit; Mauceli, Evan; Morin, Emmanuelle; Murat, Claude; Pangilinan, Jasmyn L.; Park, Robert; Pearson, Matthew; Quesneville, Hadi; Rouhier, Nicolas; Sakthikumar, Sharadha; Salamov, Asaf A.; Schmutz, Jeremy; Selles, Benjamin; Shapiro, Harris; Tangay, Philippe; Tuskan, Gerald A.; Peer, Yves Van de; Henrissat, Bernard; Rouze, Pierre; Ellis, Jeffrey G.; Dodds, Peter N.; Schein, Jacqueline E.; Zhong, Shaobin; Hamelin, Richard C.; Grigoriev, Igor V.; Szabo, Les J.; Martin1, Francis

2011-04-27

Rust fungi are some of the most devastating pathogens of crop plants. They are obligate biotrophs, which extract nutrients only from living plant tissues and cannot grow apart from their hosts. Their lifestyle has slowed the dissection of molecular mechanisms underlying host invasion and avoidance or suppression of plant innate immunity. We sequenced the 101 mega base pair genome of Melampsora larici-populina, the causal agent of poplar leaf rust, and the 89 mega base pair genome of Puccinia graminis f. sp. tritici, the causal agent of wheat and barley stem rust. We then compared the 16,841 predicted proteins of M. larici-populina to the 18,241 predicted proteins of P. graminis f. sp tritici. Genomic features related to their obligate biotrophic life-style include expanded lineage-specific gene families, a large repertoire of effector-like small secreted proteins (SSPs), impaired nitrogen and sulfur assimilation pathways, and expanded families of amino-acid, oligopeptide and hexose membrane transporters. The dramatic upregulation of transcripts coding for SSPs, secreted hydrolytic enzymes, and transporters in planta suggests that they play a role in host infection and nutrient acquisition. Some of these genomic hallmarks are mirrored in the genomes of other microbial eukaryotes that have independently evolved to infect plants, indicating convergent adaptation to a biotrophic existence inside plant cells

Yellow Rust Epidemics Worldwide Were Caused by Pathogen Races from Divergent Genetic Lineages

Science.gov (United States)

Ali, Sajid; Rodriguez-Algaba, Julian; Thach, Tine; Sørensen, Chris K.; Hansen, Jens G.; Lassen, Poul; Nazari, Kumarse; Hodson, David P.; Justesen, Annemarie F.; Hovmøller, Mogens S.

2017-01-01

We investigated whether the recent worldwide epidemics of wheat yellow rust were driven by races of few clonal lineage(s) or populations of divergent races. Race phenotyping of 887 genetically diverse Puccinia striiformis isolates sampled in 35 countries during 2009–2015 revealed that these epidemics were often driven by races from few but highly divergent genetic lineages. PstS1 was predominant in North America; PstS2 in West Asia and North Africa; and both PstS1 and PstS2 in East Africa. PstS4 was prevalent in Northern Europe on triticale; PstS5 and PstS9 were prevalent in Central Asia; whereas PstS6 was prevalent in epidemics in East Africa. PstS7, PstS8 and PstS10 represented three genetic lineages prevalent in Europe. Races from other lineages were in low frequencies. Virulence to Yr9 and Yr27 was common in epidemics in Africa and Asia, while virulence to Yr17 and Yr32 were prevalent in Europe, corresponding to widely deployed resistance genes. The highest diversity was observed in South Asian populations, where frequent recombination has been reported, and no particular race was predominant in this area. The results are discussed in light of the role of invasions in shaping pathogen population across geographical regions. The results emphasized the lack of predictability of emergence of new races with high epidemic potential, which stresses the need for additional investments in population biology and surveillance activities of pathogens on global food crops, and assessments of disease vulnerability of host varieties prior to their deployment at larger scales. PMID:28676811

Yellow Rust Epidemics Worldwide Were Caused by Pathogen Races from Divergent Genetic Lineages

Directory of Open Access Journals (Sweden)

Sajid Ali

2017-06-01

Full Text Available We investigated whether the recent worldwide epidemics of wheat yellow rust were driven by races of few clonal lineage(s or populations of divergent races. Race phenotyping of 887 genetically diverse Puccinia striiformis isolates sampled in 35 countries during 2009–2015 revealed that these epidemics were often driven by races from few but highly divergent genetic lineages. PstS1 was predominant in North America; PstS2 in West Asia and North Africa; and both PstS1 and PstS2 in East Africa. PstS4 was prevalent in Northern Europe on triticale; PstS5 and PstS9 were prevalent in Central Asia; whereas PstS6 was prevalent in epidemics in East Africa. PstS7, PstS8 and PstS10 represented three genetic lineages prevalent in Europe. Races from other lineages were in low frequencies. Virulence to Yr9 and Yr27 was common in epidemics in Africa and Asia, while virulence to Yr17 and Yr32 were prevalent in Europe, corresponding to widely deployed resistance genes. The highest diversity was observed in South Asian populations, where frequent recombination has been reported, and no particular race was predominant in this area. The results are discussed in light of the role of invasions in shaping pathogen population across geographical regions. The results emphasized the lack of predictability of emergence of new races with high epidemic potential, which stresses the need for additional investments in population biology and surveillance activities of pathogens on global food crops, and assessments of disease vulnerability of host varieties prior to their deployment at larger scales.

Heritable, De Novo Resistance to Leaf Rust and Other Novel Traits in Selfed Descendants of Wheat Responding to Inoculation with Wheat Streak Mosaic Virus

Science.gov (United States)

Seifers, Dallas L.; Haber, Steve; Martin, Terry J.; McCallum, Brent D.

2014-01-01

Stable resistance to infection with Wheat streak mosaic virus (WSMV) can be evolved de novo in selfing bread wheat lines subjected to cycles of WSMV inoculation and selection of best-performing plants or tillers. To learn whether this phenomenon might be applied to evolve resistance de novo to pathogens unrelated to WSMV, we examined the responses to leaf rust of succeeding generations of the rust- and WSMV-susceptible cultivar ‘Lakin’ following WSMV inoculation and derived rust-resistant sublines. After three cycles of the iterative protocol five plants, in contrast to all others, expressed resistance to leaf and stripe rust. A subset of descendant sublines of one of these, ‘R1’, heritably and uniformly expressed the new trait of resistance to leaf rust. Such sublines, into which no genes from a known source of resistance had been introgressed, conferred resistance to progeny of crosses with susceptible parents. The F1 populations produced from crosses between, respectively, susceptible and resistant ‘Lakin’ sublines 4-3-3 and 4-12-3 were not all uniform in their response to seedling inoculation with race TDBG. In seedling tests against TDBG and MKPS races the F2s from F1 populations that were uniformly resistant had 3∶1 ratios of resistant to susceptible individuals but the F2s from susceptible F1 progenitors were uniformly susceptible. True-breeding lines derived from resistant individuals in F2 populations were resistant to natural stripe and leaf rust inoculum in the field, while the ‘Lakin’ progenitor was susceptible. The next generation of six of the ‘Lakin’-derived lines exhibited moderate to strong de novo resistance to stem rust races TPMK, QFCS and RKQQ in seedling tests while the ‘Lakin’ progenitor was susceptible. These apparently epigenetic effects in response to virus infection may help researchers fashion a new tool that expands the range of genetic resources already available in adapted germplasm. PMID:24497941

Differential gene expression in loblolly pine (Pinus taeda L.) challenged with the fusiform rust fungus, Cronartium quercuum f.sp. fusiforme

Science.gov (United States)

Henrietta Myburg; Alison M. Morse; Henry V. Amerson; Thomas L. Kubisiak; Dudley Huber; Jason A. Osborne; Saul A. Garcia; C. Dana Nelson; John M. Davis; Sarah F. Covert; Leonel M. van Zyle

2006-01-01

Cronartium quercuum f.sp. fusiforme is the pathogen that incites fusiform rust disease of southern pine species. To date, a number of host resistance genes have been mapped. Although genomic mapping studies have provided valuable information on the genetic basis of disease interactions in this pine-rust pathosystem, the interaction...

Forest pathogens and diseases under changing climate-A review

International Nuclear Information System (INIS)

Raza, M. M.; Khan, M. A.; Aslam, H. M. U.; Riaz, K.

2015-01-01

Changing climate threatens tree health by affecting the likelihood, frequency of occurrence, types and severity of forest diseases caused by diverse pests, resultantly altering the forest ecosystems. The present review covers the relationship between climate and diverse cases of forest diseases and potential shocks of climate change on pathogens and diseases. Biotic diseases, cankers, decays, declines, foliar diseases, root diseases and stem rust of pine have been reviewed with some illustrations of potential disease effects with predicted changing climate. The impact of changing climate on host, pathogen, and their interaction will have frequent and mostly unsympathetic outcomes to forest ecosystems. By employing the proactive and modern scientific management strategies like monitoring, modeling prediction, risk rating, planning, genetic diversity and facilitated migration, genetic protection and breeding for disease resistance and relating results to forest policy, planning as well as decision making, the suspicions innate to climate change effects can be minimized. (author)

Flavan-3-ols Are an Effective Chemical Defense against Rust Infection.

Science.gov (United States)

Ullah, Chhana; Unsicker, Sybille B; Fellenberg, Christin; Constabel, C Peter; Schmidt, Axel; Gershenzon, Jonathan; Hammerbacher, Almuth

2017-12-01

Phenolic secondary metabolites are often thought to protect plants against attack by microbes, but their role in defense against pathogen infection in woody plants has not been investigated comprehensively. We studied the biosynthesis, occurrence, and antifungal activity of flavan-3-ols in black poplar ( Populus nigra ), which include both monomers, such as catechin, and oligomers, known as proanthocyanidins (PAs). We identified and biochemically characterized three leucoanthocyanidin reductases and two anthocyanidin reductases from P. nigra involved in catalyzing the last steps of flavan-3-ol biosynthesis, leading to the formation of catechin [2,3-trans-(+)-flavan-3-ol] and epicatechin [2,3-cis-(-)-flavan-3-ol], respectively. Poplar trees that were inoculated with the biotrophic rust fungus ( Melampsora larici-populina ) accumulated higher amounts of catechin and PAs than uninfected trees. The de novo-synthesized catechin and PAs in the rust-infected poplar leaves accumulated significantly at the site of fungal infection in the lower epidermis. In planta concentrations of these compounds strongly inhibited rust spore germination and reduced hyphal growth. Poplar genotypes with constitutively higher levels of catechin and PAs as well as hybrid aspen ( Populus tremula × Populus alba ) overexpressing the MYB134 transcription factor were more resistant to rust infection. Silencing PnMYB134 , on the other hand, decreased flavan-3-ol biosynthesis and increased susceptibility to rust infection. Taken together, our data indicate that catechin and PAs are effective antifungal defenses in poplar against foliar rust infection. © 2017 American Society of Plant Biologists. All Rights Reserved.

Major transcriptome reprogramming underlies floral mimicry induced by the rust fungus Puccinia monoica in Boechera stricta.

Directory of Open Access Journals (Sweden)

Liliana M Cano

Full Text Available Pucciniamonoica is a spectacular plant parasitic rust fungus that triggers the formation of flower-like structures (pseudoflowers in its Brassicaceae host plant Boecherastricta. Pseudoflowers mimic in shape, color, nectar and scent co-occurring and unrelated flowers such as buttercups. They act to attract insects thereby aiding spore dispersal and sexual reproduction of the rust fungus. Although much ecological research has been performed on P. monoica-induced pseudoflowers, this system has yet to be investigated at the molecular or genomic level. To date, the molecular alterations underlying the development of pseudoflowers and the genes involved have not been described. To address this, we performed gene expression profiling to reveal 256 plant biological processes that are significantly altered in pseudoflowers. Among these biological processes, plant genes involved in cell fate specification, regulation of transcription, reproduction, floral organ development, anthocyanin (major floral pigments and terpenoid biosynthesis (major floral volatile compounds were down-regulated in pseudoflowers. In contrast, plant genes involved in shoot, cotyledon and leaf development, carbohydrate transport, wax biosynthesis, cutin transport and L-phenylalanine metabolism (pathway that results in phenylethanol and phenylacetaldehyde volatile production were up-regulated. These findings point to an extensive reprogramming of host genes by the rust pathogen to induce floral mimicry. We also highlight 31 differentially regulated plant genes that are enriched in the biological processes mentioned above, and are potentially involved in the formation of pseudoflowers. This work illustrates the complex perturbations induced by rust pathogens in their host plants, and provides a starting point for understanding the molecular mechanisms of pathogen-induced floral mimicry.

Sequencing Ug99 and Other Stem Rust Races: Progress and Results

Science.gov (United States)

Over the last decade a number of different molecular methods have been used to characterize genetic diversity in Puccinia graminis. Multilocus DNA fingerprinting methods (AFLPs, RAPDs, SAMs and S-SAPs) have proven to be useful, but limited to phenotypic analysis due to the dikaryotic nature of rust ...

Colonization history, host distribution, anthropogenic influence and landscape features shape populations of white pine blister rust, an invasive alien tree pathogen.

Directory of Open Access Journals (Sweden)

Simren Brar

Full Text Available White pine blister rust is caused by the fungal pathogen Cronartium ribicola J.C. Fisch (Basidiomycota, Pucciniales. This invasive alien pathogen was introduced into North America at the beginning of the 20th century on pine seedlings imported from Europe and has caused serious economic and ecological impacts. In this study, we applied a population and landscape genetics approach to understand the patterns of introduction and colonization as well as population structure and migration of C. ribicola. We characterized 1,292 samples of C. ribicola from 66 geographic locations in North America using single nucleotide polymorphisms (SNPs and evaluated the effect of landscape features, host distribution, and colonization history on the structure of these pathogen populations. We identified eastern and western genetic populations in North America that are strongly differentiated. Genetic diversity is two to five times higher in eastern populations than in western ones, which can be explained by the repeated accidental introductions of the pathogen into northeastern North America compared with a single documented introduction into western North America. These distinct genetic populations are maintained by a barrier to gene flow that corresponds to a region where host connectivity is interrupted. Furthermore, additional cryptic spatial differentiation was identified in western populations. This differentiation corresponds to landscape features, such as mountain ranges, and also to host connectivity. We also detected genetic differentiation between the pathogen populations in natural stands and plantations, an indication that anthropogenic movement of this pathogen still takes place. These results highlight the importance of monitoring this invasive alien tree pathogen to prevent admixture of eastern and western populations where different pathogen races occur.

76 FR 13970 - Notice of Request for Extension of Approval of an Information Collection; Black Stem Rust...

Science.gov (United States)

2011-03-15

... Requirements for Addition of Rust-Resistant Varieties AGENCY: Animal and Plant Health Inspection Service, USDA... Rust-Resistant Varieties. OMB Number: 0579-0186. Type of Request: Extension of approval of an... products to prevent the introduction of plant pests into the United States or their dissemination within...

Characterization and comparative analysis of the genome of Puccinia sorghi Schwein, the causal agent of maize common rust.

Science.gov (United States)

Rochi, Lucia; Diéguez, María José; Burguener, Germán; Darino, Martín Alejandro; Pergolesi, María Fernanda; Ingala, Lorena Romina; Cuyeu, Alba Romina; Turjanski, Adrián; Kreff, Enrique Domingo; Sacco, Francisco

2018-03-01

Rust fungi are one of the most devastating pathogens of crop plants. The biotrophic fungus Puccinia sorghi Schwein (Ps) is responsible for maize common rust, an endemic disease of maize (Zea mays L.) in Argentina that causes significant yield losses in corn production. In spite of this, the Ps genomic sequence was not available. We used Illumina sequencing to rapidly produce the 99.6Mbdraft genome sequence of Ps race RO10H11247, derived from a single-uredinial isolate from infected maize leaves collected in the Argentine Corn Belt Region during 2010. High quality reads were obtained from 200bppaired-end and 5000bpmate-paired libraries and assembled in 15,722 scaffolds. A pipeline which combined an ab initio program with homology-based models and homology to in planta enriched ESTs from four cereal pathogenic fungus (the three sequenced wheat rusts and Ustilago maydis) was used to identify 21,087 putative coding sequences, of which 1599 might be part of the Ps RO10H11247 secretome. Among the 458 highly conserved protein families from the euKaryotic Orthologous Groups (KOG) that occur in a wide range of eukaryotic organisms, 97.5% have at least one member with high homology in the Ps assembly (TBlastN, E-value⩽e-10) covering more than 50% of the length of the KOG protein. Comparative studies with the three sequenced wheat rust fungus, and microsynteny analysis involving Puccinia striiformis f. sp. tritici (Pst, wheat stripe rust fungus), support the quality achieved. The results presented here show the effectiveness of the Illumina strategy for sequencing dikaryotic genomes of non-model organisms and provides reliable DNA sequence information for genomic studies, including pathogenic mechanisms of this maize fungus and molecular marker design. Copyright © 2016 Elsevier Inc. All rights reserved.

Determination of Radiographic Healing: An Assessment of Consistency Using RUST and Modified RUST in Metadiaphyseal Fractures.

Science.gov (United States)

Litrenta, Jody; Tornetta, Paul; Mehta, Samir; Jones, Clifford; OʼToole, Robert V; Bhandari, Mohit; Kottmeier, Stephen; Ostrum, Robert; Egol, Kenneth; Ricci, William; Schemitsch, Emil; Horwitz, Daniel

2015-11-01

To determine the reliability of the Radiographic Union Scale for Tibia (RUST) score and a new modified RUST score in quantifying healing and to define a value for radiographic union in a large series of metadiaphyseal fractures treated with plates or intramedullary nails. Healing was evaluated using 2 methods: (1) evaluation of interrater agreement in a series of radiographs and (2) analysis of prospectively gathered data from 2 previous large multicenter trials to define thresholds for radiographic union. Part 1: 12 orthopedic trauma surgeons evaluated a series of radiographs of 27 distal femur fractures treated with either plate or retrograde nail fixation at various stages of healing in random order using a modified RUST score. For each radiographic set, the reviewer indicated if the fracture was radiographically healed. Part 2: The radiographic results of 2 multicenter randomized trials comparing plate versus nail fixation of 81 distal femur and 46 proximal tibia fractures were reviewed. Orthopaedic surgeons at 24 trauma centers scored radiographs at 3, 6, and 12 months postoperatively using the modified RUST score above. Additionally, investigators indicated if the fracture was healed or not healed. The intraclass correlation coefficient (ICC) with 95% confidence intervals was determined for each cortex, the standard and modified RUST score, and the assignment of union for part 1 data. The RUST and modified RUST that defined "union" were determined for both parts of the study. ICC: The modified RUST score demonstrated slightly higher ICCs than the standard RUST (0.68 vs. 0.63). Nails had substantial agreement, whereas plates had moderate agreement using both modified and standard RUST (0.74 and 0.67 vs. 0.59 and 0.53). The average standard and modified RUST at union among all fractures was 8.5 and 11.4. Nails had higher standard and modified RUST scores than plates at union. The ICC for union was 0.53 (nails: 0.58; plates: 0.51), which indicates moderate

Crown rust control on oats

International Nuclear Information System (INIS)

Frey, K.J.; Browning, J.A.; Simons, M.D.

1976-01-01

Attempts have been made to test the relative effectiveness of EMS treatment for inducing tolerance to crown rust among oat strains Clintland-60 of different ploidy levels. One strain of diploid and one of tetraploid oats were treated with EMS. These two strains are as susceptible to damage from crown rust as are cultivars of hexaploid oats. Multiline cultivars of oats have been shown to provide adequate protection from economic loss due to crown-rust disease in Iowa. Since 1968, eleven multiline cultivars of oats have been released from the Iowa station for use in commercial production in the midwestern USA. During the past two winter seasons, the effectiveness of multiline oat cultivars against crown-rust disease has been researched in Texas, USA, which has a ''long rust season'' of about four months, not an Iowa ''short rust season''. The protection against crown rust afforded by the multiline cultivars appeared equally good in Texas and Iowa. The seasonal productions of crown-rust spores relative to completely resistant and susceptible checks were nearly identical in both environments. Fifteen new isolines of oats have been developed for use in multiline varieties, with seed supplies sufficiently large for immediate use

Preempting the pathogen: Blister rust and proactive management of high-elevation pines

Science.gov (United States)

Sue Miller; Anna Schoettle; Kelly Burns; Richard Sniezko; Patty Champ

2017-01-01

White pine blister rust has been spreading through western forests since 1910, causing widespread mortality in a group that includes some of the oldest and highest-elevation pines in the United States. The disease has recently reached Colorado and is expected to travel through the southern Rockies. Although it cannot be contained, RMRS researchers and collaborators are...

Flavan-3-ols Are an Effective Chemical Defense against Rust Infection1[OPEN

Science.gov (United States)

Unsicker, Sybille B.; Fellenberg, Christin; Schmidt, Axel

2017-01-01

Phenolic secondary metabolites are often thought to protect plants against attack by microbes, but their role in defense against pathogen infection in woody plants has not been investigated comprehensively. We studied the biosynthesis, occurrence, and antifungal activity of flavan-3-ols in black poplar (Populus nigra), which include both monomers, such as catechin, and oligomers, known as proanthocyanidins (PAs). We identified and biochemically characterized three leucoanthocyanidin reductases and two anthocyanidin reductases from P. nigra involved in catalyzing the last steps of flavan-3-ol biosynthesis, leading to the formation of catechin [2,3-trans-(+)-flavan-3-ol] and epicatechin [2,3-cis-(−)-flavan-3-ol], respectively. Poplar trees that were inoculated with the biotrophic rust fungus (Melampsora larici-populina) accumulated higher amounts of catechin and PAs than uninfected trees. The de novo-synthesized catechin and PAs in the rust-infected poplar leaves accumulated significantly at the site of fungal infection in the lower epidermis. In planta concentrations of these compounds strongly inhibited rust spore germination and reduced hyphal growth. Poplar genotypes with constitutively higher levels of catechin and PAs as well as hybrid aspen (Populus tremula × Populus alba) overexpressing the MYB134 transcription factor were more resistant to rust infection. Silencing PnMYB134, on the other hand, decreased flavan-3-ol biosynthesis and increased susceptibility to rust infection. Taken together, our data indicate that catechin and PAs are effective antifungal defenses in poplar against foliar rust infection. PMID:29070515

The Big Rust and the Red Queen: Long-Term Perspectives on Coffee Rust Research.

Science.gov (United States)

McCook, Stuart; Vandermeer, John

2015-09-01

Since 2008, there has been a cluster of outbreaks of the coffee rust (Hemileia vastatrix) across the coffee-growing regions of the Americas, which have been collectively described as the Big Rust. These outbreaks have caused significant hardship to coffee producers and laborers. This essay situates the Big Rust in a broader historical context. Over the past two centuries, coffee farmers have had to deal with the "curse of the Red Queen"-the need to constantly innovate in the face of an increasing range of threats, which includes the rust. Over the 20th century, particularly after World War II, national governments and international organizations developed a network of national, regional, and international coffee research institutions. These public institutions played a vital role in helping coffee farmers manage the rust. Coffee farmers have pursued four major strategies for managing the rust: bioprospecting for resistant coffee plants, breeding resistant coffee plants, chemical control, and agroecological control. Currently, the main challenge for researchers is to develop rust control strategies that are both ecologically and economically viable for coffee farmers, in the context of a volatile, deregulated coffee industry and the emergent challenges of climate change.

Induced mutations in beans and peas for resistance to rust

International Nuclear Information System (INIS)

Fadl, F.A.M.

1983-01-01

Gamma rays and ethyl methanesulphonate (EMS) were applied in a mutation-induction programme for rust resistance in bean and pea. Bean and pea seeds were pre-soaked 2 hours before irradiation with 9, 10 and 12 krad. For chemical mutagen treatments bean and pea seeds were pre-soaked for 8 hours and treated with 0.5 and 1.5% EMS for four hours. M 2 seeds of beans and peas were planted in 1979. Resistant M 2 plants were selected for their rust resistance and other morphological characters. M 3 seeds of selected plants were planted in 1980. In 1980 more seeds of the same varieties of beans and peas were treated with 0.1 and 0.3% EMS with the aim to produce rust-resistant mutants. Seed germination was reduced by gamma rays or EMS. Dwarf, malformed and abnormal plants were noticed. Some resistant M 2 plants selected gave high grain yields. Some were different in morphological characters. In the M 3 of selected plants various other mutant characters appeared, such as different height of plants, early and late flowering, resistance to powdery mildew in peas, altered grain yield, thickness of stem, pod shape and flower colour. (author)

Genetics and mapping of a new leaf rust resistance gene in Triticum ...

Indian Academy of Sciences (India)

A Triticum timopheevii-derived bread wheat line, Selection G12, was screened with 40 pathotypes of leaf rust pathogen, Puccinia triticina at seedling stage and with two most commonly prevalent pathotypes 77-5 and 104-2 at adult plant stage. Selection G12 showed resistance at both seedling and adult plant stages.

Secretome Characterization and Correlation Analysis Reveal Putative Pathogenicity Mechanisms and Identify Candidate Avirulence Genes in the Wheat Stripe Rust Fungus Puccinia striiformis f. sp. tritici.

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Xia, Chongjing; Wang, Meinan; Cornejo, Omar E; Jiwan, Derick A; See, Deven R; Chen, Xianming

2017-01-01

Stripe (yellow) rust, caused by Puccinia striiformis f. sp. tritici ( Pst ), is one of the most destructive diseases of wheat worldwide. Planting resistant cultivars is an effective way to control this disease, but race-specific resistance can be overcome quickly due to the rapid evolving Pst population. Studying the pathogenicity mechanisms is critical for understanding how Pst virulence changes and how to develop wheat cultivars with durable resistance to stripe rust. We re-sequenced 7 Pst isolates and included additional 7 previously sequenced isolates to represent balanced virulence/avirulence profiles for several avirulence loci in seretome analyses. We observed an uneven distribution of heterozygosity among the isolates. Secretome comparison of Pst with other rust fungi identified a large portion of species-specific secreted proteins, suggesting that they may have specific roles when interacting with the wheat host. Thirty-two effectors of Pst were identified from its secretome. We identified candidates for Avr genes corresponding to six Yr genes by correlating polymorphisms for effector genes to the virulence/avirulence profiles of the 14 Pst isolates. The putative AvYr76 was present in the avirulent isolates, but absent in the virulent isolates, suggesting that deleting the coding region of the candidate avirulence gene has produced races virulent to resistance gene Yr76 . We conclude that incorporating avirulence/virulence phenotypes into correlation analysis with variations in genomic structure and secretome, particularly presence/absence polymorphisms of effectors, is an efficient way to identify candidate Avr genes in Pst . The candidate effector genes provide a rich resource for further studies to determine the evolutionary history of Pst populations and the co-evolutionary arms race between Pst and wheat. The Avr candidates identified in this study will lead to cloning avirulence genes in Pst , which will enable us to understand molecular mechanisms

Blister rust resistance among 19 families of whitebark pine, Pinus albicaulis, from Oregon and Washington – early results from an artificial inoculation trial

Science.gov (United States)

Angelia Kegley; Richard A. Sniezko; Robert Danchok; Douglas P. Savin

2012-01-01

Whitebark pine is considered one of the most susceptible white pine species to white pine blister rust, the disease caused by the non-native pathogen Cronartium ribicola. High mortality from blister rust and other factors in much of the range in the United States and Canada have raised serious concerns about the future viability of this high-...

Rust resistance evaluation of advanced wheat (triticum aestivum l.) genotypes using pcr-based dna markers

International Nuclear Information System (INIS)

Rahman, S.U.; Younis, M.; Iqbal, M.Z.; Nawaz, M.

2014-01-01

The most effective and environmental friendly approach for the control of wheat rust disease is the use of resistant genotypes. The present study was conducted to explore rust resistance potential of 85 elite wheat genotypes (36 varieties and 49 advanced lines) using various types of DNA markers like STS, SCAR and SSR. DNA markers linked with different genes conferring resistance to rusts (Leaf rust=Lr, Yellow rust=Yr and Stem rust=Sr) were employed in this study. A total of 18 genes, consisting of eleven Lr (lr1, lr10, lr19, lr21, lr28, lr34, lr39, lr46, lr47, lr51 and lr52), four Yr (yr5, yr18, yr26 and yr29) and three Sr genes (sr2, sr29, and sr36) were studied through linked DNA markers. Maximum number of Lr genes was found in 17 advanced lines and 9 varieties, Yr genes in 26 advanced lines and 20 wheat varieties, and Sr genes in 43 advanced lines and 27 varieties. Minimum number of Lr genes was found in advanced line D-97 and variety Kohinoor-83, Yr genes in wheat variety Bwp-97 and Sr genes in 6 advanced lines and 8 varieties. Molecular data revealed that genotypes having same origin, from a specified area showed resistance for similar type of genes. In this study, an average similarity of 84% was recorded among wheat genotypes. Out of 18 loci, 15 were found to be polymorphic. (author)

Comparative transcriptome analysis and identification of candidate effectors in two related rust species (Gymnosporangium yamadae and Gymnosporangium asiaticum).

Science.gov (United States)

Tao, Si-Qi; Cao, Bin; Tian, Cheng-Ming; Liang, Ying-Mei

2017-08-23

Rust fungi constitute the largest group of plant fungal pathogens. However, a paucity of data, including genomic sequences, transcriptome sequences, and associated molecular markers, hinders the development of inhibitory compounds and prevents their analysis from an evolutionary perspective. Gymnosporangium yamadae and G. asiaticum are two closely related rust fungal species, which are ecologically and economically important pathogens that cause apple rust and pear rust, respectively, proved to be devastating to orchards. In this study, we investigated the transcriptomes of these two Gymnosporangium species during the telial stage of their lifecycles. The aim of this study was to understand the evolutionary patterns of these two related fungi and to identify genes that developed by selection. The transcriptomes of G. yamadae and G. asiaticum were generated from a mixture of RNA from three biological replicates of each species. We obtained 49,318 and 54,742 transcripts, with N50 values of 1957 and 1664, for G. yamadae and G. asiaticum, respectively. We also identified a repertoire of candidate effectors and other gene families associated with pathogenicity. A total of 4947 pairs of putative orthologues between the two species were identified. Estimation of the non-synonymous/synonymous substitution rate ratios for these orthologues identified 116 pairs with Ka/Ks values greater than1 that are under positive selection and 170 pairs with Ka/Ks values of 1 that are under neutral selection, whereas the remaining 4661 genes are subjected to purifying selection. We estimate that the divergence time between the two species is approximately 5.2 Mya. This study constitutes a de novo assembly and comparative analysis between the transcriptomes of the two rust species G. yamadae and G. asiaticum. The results identified several orthologous genes, and many expressed genes were identified by annotation. Our analysis of Ka/Ks ratios identified orthologous genes subjected to

Discovery of a seventh Rpp soybean rust resistance locus in soybean accession PI 605823

Science.gov (United States)

Soybean rust, caused by the obligate biotrophic fungal pathogen Phakopsora pachyrhizi Syd. & Syd, is a disease threat to soybean production in regions of the world with mild winters. Host plant resistance to P. pachyrhizi conditioned by Rpp genes has been found in numerous soybean accessions, and at...

Rust disease of eucalypts, caused by Puccinia psidii, did not originate via host jump from guava in Brazil

Science.gov (United States)

Rodrigo N. Graca; Amy L. Ross-Davis; Ned B. Klopfenstein; Mee-Sook Kim; Tobin L. Peever; Phil G. Cannon; Cristina P. Aun; Eduardo G. Mizubuti; Acelino C. Alfenas

2013-01-01

The rust fungus, Puccinia psidii, is a devastating pathogen of introduced eucalypts (Eucalyptus spp.) in Brazil where it was first observed in 1912. This pathogen is hypothesized to be endemic to South and Central America and to have first infected eucalypts via a host jump from native guava (Psidium guajava). Ten microsatellite markers were used to genotype 148 P....

Stem rots of oil palm caused by Ganoderma boninense: pathogen biology and epidemiology.

Science.gov (United States)

Pilotti, C A

2005-01-01

Oil palm (Elaeis guineensis Jacq.) has been grown in Papua New Guinea since the early 1960s. The most important disease of oil palm in PNG is a stem rot of the palm base. This is the same disease that constitutes a major threat to sustainable oil palm production in SE Asia. Investigations into the causal pathogen have revealed that the stem rots in PNG are caused predominantly by the basidiomycete Ganoderma boninense, with a minor pathogen identified as G. tornatum G. tornatum was found to have a broad host range whereas G. boninense appears to be restricted to palms. The population structure of G. boninense was investigated using inter-fertility studies between isolates collected from basal stem rots on oil palm. Although the G. boninense field populations are predominantly comprised of distinct individuals, a number of isolates were found that share single mating alleles. This indicates that out-crossing had occurred over several generations in the resident or wild population of G. boninense prior to colonization of oil palm. No direct hereditary relationship between isolates on neighbouring diseased palms was found, although an indirect link between isolates causing upper stem rot and basal stem rot was detected.

Structural studies on the development of soybean rust (Phakopsora pachyrhizi Syd.) in susceptible soybean leaves

International Nuclear Information System (INIS)

Koch, E.; Ebrahim-Nesbat, F.; Hoppe, H.H.

1983-01-01

Where soybeans are cultivated in the tropics, soybean rust may cause heavy crop losses. Resistance found so far was only of local and temporary value. More substantial breeding efforts are needed, but these may require a better understanding of the pathogen's biology and evolutionary capacity, the infection process and the host-pathogen relationships. The report deals with the infection process and the development of the fungus in a susceptible host variety. (author)

Multi-location wheat stripe rust QTL analysis: genetic background and epistatic interactions.

Science.gov (United States)

Vazquez, M Dolores; Zemetra, Robert; Peterson, C James; Chen, Xianming M; Heesacker, Adam; Mundt, Christopher C

2015-07-01

Epistasis and genetic background were important influences on expression of stripe rust resistance in two wheat RIL populations, one with resistance conditioned by two major genes and the other conditioned by several minor QTL. Stripe rust is a foliar disease of wheat (Triticum aestivum L.) caused by the air-borne fungus Puccinia striiformis f. sp. tritici and is present in most regions around the world where commercial wheat is grown. Breeding for durable resistance to stripe rust continues to be a priority, but also is a challenge due to the complexity of interactions among resistance genes and to the wide diversity and continuous evolution of the pathogen races. The goal of this study was to detect chromosomal regions for resistance to stripe rust in two winter wheat populations, 'Tubbs'/'NSA-98-0995' (T/N) and 'Einstein'/'Tubbs' (E/T), evaluated across seven environments and mapped with diversity array technology and simple sequence repeat markers covering polymorphic regions of ≈1480 and 1117 cM, respectively. Analysis of variance for phenotypic data revealed significant (P located in chromosomes 2AS and 6AL, with epistatic interaction between them, were responsible for the main phenotypic response. For the T/N population, eight QTL were identified, with those in chromosomes 2AL and 2BL accounting for the largest percentage of the phenotypic variance.

First report of the white pine blister rust pathogen, Cronartium ribicola, in Arizona

Science.gov (United States)

M. L. Fairweather; Brian Geils

2011-01-01

White pine blister rust, caused by Cronartium ribicola J.C. Fisch., was found on southwestern white pine (Pinus flexilis James var. reflexa Engelm., synonym P. strobiformis Engelm.) near Hawley Lake, Arizona (Apache County, White Mountains, 34.024°N, 109.776°W, elevation 2,357 m) in April 2009. Although white pines in the Southwest (Arizona and New Mexico) have been...

Genomic analyses and expression evaluation of thaumatin-like gene family in the cacao fungal pathogen Moniliophthora perniciosa.

Science.gov (United States)

Franco, Sulamita de Freitas; Baroni, Renata Moro; Carazzolle, Marcelo Falsarella; Teixeira, Paulo José Pereira Lima; Reis, Osvaldo; Pereira, Gonçalo Amarante Guimarães; Mondego, Jorge Maurício Costa

2015-10-30

Thaumatin-like proteins (TLPs) are found in diverse eukaryotes. Plant TLPs, known as Pathogenicity Related Protein (PR-5), are considered fungal inhibitors. However, genes encoding TLPs are frequently found in fungal genomes. In this work, we have identified that Moniliophthora perniciosa, a basidiomycete pathogen that causes the Witches' Broom Disease (WBD) of cacao, presents thirteen putative TLPs from which four are expressed during WBD progression. One of them is similar to small TLPs, which are present in phytopathogenic basidiomycete, such as wheat stem rust fungus Puccinia graminis. Fungi genomes annotation and phylogenetic data revealed a larger number of TLPs in basidiomycetes when comparing with ascomycetes, suggesting that these proteins could be involved in specific traits of mushroom-forming species. Based on the present data, we discuss the contribution of TLPs in the combat against fungal competitors and hypothesize a role of these proteins in M. perniciosa pathogenicity. Copyright © 2015 Elsevier Inc. All rights reserved.

Mapping fusiform rust resistance genes within a complex mating design of loblolly pine

Science.gov (United States)

Tania Quesada; Marcio F.R. Resende Jr.; Patricio Munoz; Jill L. Wegrzyn; David B. Neale; Matias Kirst; Gary F. Peter; Salvador A. Gezan; C.Dana Nelson; John M. Davis

2014-01-01

Fusiform rust resistance can involve gene-for-gene interactions where resistance (Fr) genes in the host interact with corresponding avirulence genes in the pathogen, Cronartium quercuum f.sp. fusiforme (Cqf). Here, we identify trees with Fr genes in a loblolly pine population derived from a complex mating design challenged with two Cqf inocula (one gall and 10 gall...

Rust dissolution and removal by iron-reducing bacteria: A potential rehabilitation of rusted equipment

International Nuclear Information System (INIS)

Starosvetsky, J.; Kamari, R.; Farber, Y.; Bilanović, D.; Armon, R.

2016-01-01

Highlights: • The present study demonstrated the high reductive capacity of both strains: the collection S. oneidensis and the wild strain Geobacter spp. (soil isolate). • The experimental strains were successful in Fe 3+ reduction for both states: soluble and crystalline (originally prepared from rust). • Rust dissolution can be improved by: addition of AFC at low concentration (0.2 g/l), increasing bacterial initial inoculum and rust reactive surface. • Both experimental IRB strains were able to completely remove previously formed rust on carbon steel coupons. • Additional results (not showed) revealed that culture S. oneidensis and the environmental isolate Geobacter spp., apparently have a different mechanism of iron reduction that requires further study. - Abstract: Iron reducing bacteria (IRB), to be used in rust dissolution and removal, have been isolated and enriched from different environmental sources. Comparative measurements revealed that a soil isolate (Geobacter sulfurreducens sp.) had the highest reductive activity equivalent to Shewanella oneidensis (strain CIP 106686, pure culture). Both reductive microorganisms can use Fe 3+ ions as electron acceptors from soluble as well as from crystalline sources. In nutrient medium containing soluble Fe 3+ , the highest reductive activity obtained for G. sulfurreducens sp. and S. oneidensis was 93 and 97% respectively. Successful removal of rust from carbon steel coupons has been achieved with both experimental bacteria.

Fine Mapping of Ur-3, a Historically Important Rust Resistance Locus in Common Bean

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Oscar P. Hurtado-Gonzales

2017-02-01

Full Text Available Bean rust, caused by Uromyces appendiculatus, is a devastating disease of common bean (Phaseolus vulgaris in the Americas and Africa. The historically important Ur-3 gene confers resistance to many races of the highly variable bean rust pathogen that overcome other rust resistance genes. Existing molecular markers tagging Ur-3 for use in marker-assisted selection produce false results. Here, we describe the fine mapping of the Ur-3 locus for the development of highly accurate markers linked to Ur-3. An F2 population from the cross Pinto 114 (susceptible × Aurora (resistant with Ur-3 was evaluated for its reaction to four different races of U. appendiculatus. A bulked segregant analysis using the SNP chip BARCBEAN6K_3 placed the approximate location of Ur-3 in the lower arm of chromosome Pv11. Specific SSR and SNP markers and haplotype analysis of 18 sequenced bean varieties positioned Ur-3 in a 46.5 kb genomic region from 46.96 to 47.01 Mb on Pv11. We discovered in this region the SS68 KASP marker that was tightly linked to Ur-3. Validation of SS68 on a panel of 130 diverse common bean cultivars containing all known rust resistance genes revealed that SS68 was highly accurate and produced no false results. The SS68 marker will be of great value in pyramiding Ur-3 with other rust resistance genes. It will also significantly reduce time and labor associated with the current phenotypic detection of Ur-3. This is the first utilization of fine mapping to discover markers linked to rust resistance in common bean.

Fine Mapping of Ur-3, a Historically Important Rust Resistance Locus in Common Bean.

Science.gov (United States)

Hurtado-Gonzales, Oscar P; Valentini, Giseli; Gilio, Thiago A S; Martins, Alexandre M; Song, Qijian; Pastor-Corrales, Marcial A

2017-02-09

Bean rust, caused by Uromyces appendiculatus , is a devastating disease of common bean ( Phaseolus vulgaris ) in the Americas and Africa. The historically important Ur-3 gene confers resistance to many races of the highly variable bean rust pathogen that overcome other rust resistance genes. Existing molecular markers tagging Ur-3 for use in marker-assisted selection produce false results. Here, we describe the fine mapping of the Ur-3 locus for the development of highly accurate markers linked to Ur-3 An F 2 population from the cross Pinto 114 (susceptible) × Aurora (resistant with Ur-3 ) was evaluated for its reaction to four different races of U. appendiculatus A bulked segregant analysis using the SNP chip BARCBEAN6K_3 placed the approximate location of Ur-3 in the lower arm of chromosome Pv11. Specific SSR and SNP markers and haplotype analysis of 18 sequenced bean varieties positioned Ur-3 in a 46.5 kb genomic region from 46.96 to 47.01 Mb on Pv11. We discovered in this region the SS68 KASP marker that was tightly linked to Ur-3 Validation of SS68 on a panel of 130 diverse common bean cultivars containing all known rust resistance genes revealed that SS68 was highly accurate and produced no false results. The SS68 marker will be of great value in pyramiding Ur-3 with other rust resistance genes. It will also significantly reduce time and labor associated with the current phenotypic detection of Ur-3 This is the first utilization of fine mapping to discover markers linked to rust resistance in common bean. Copyright © 2017 Hurtado-Gonzales et al.

QTLs for resistance to the false brome rust Puccinia brachypodii in the model grass Brachypodium distachyon L.

NARCIS (Netherlands)

Barbieri, M.; Marcel, T.C.; Niks, R.E.; Francia, E.; Pasquariello, M.; Mazzamurro, V.; Garvin, D.F.; Pecchioni, N.

2012-01-01

The potential of the model grass Brachypodium distachyon L. (Brachypodium) for studying grass–pathogen interactions is still underexploited. We aimed to identify genomic regions in Brachypodium associated with quantitative resistance to the false brome rust fungus Puccinia brachypodii. The inbred

In situ hybridization for the detection of rust fungi in paraffin embedded plant tissue sections

Science.gov (United States)

Rust fungi infect a wide range of plant species making them of particular interest to plant pathologists. In order to study the interactions between these important pathogenic fungi and their host plants it is useful to be able to differentiate fungal tissue from plant tissue. This can be accomplish...

Extraction of High Molecular Weight DNA from Fungal Rust Spores for Long Read Sequencing.

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Schwessinger, Benjamin; Rathjen, John P

2017-01-01

Wheat rust fungi are complex organisms with a complete life cycle that involves two different host plants and five different spore types. During the asexual infection cycle on wheat, rusts produce massive amounts of dikaryotic urediniospores. These spores are dikaryotic (two nuclei) with each nucleus containing one haploid genome. This dikaryotic state is likely to contribute to their evolutionary success, making them some of the major wheat pathogens globally. Despite this, most published wheat rust genomes are highly fragmented and contain very little haplotype-specific sequence information. Current long-read sequencing technologies hold great promise to provide more contiguous and haplotype-phased genome assemblies. Long reads are able to span repetitive regions and phase structural differences between the haplomes. This increased genome resolution enables the identification of complex loci and the study of genome evolution beyond simple nucleotide polymorphisms. Long-read technologies require pure high molecular weight DNA as an input for sequencing. Here, we describe a DNA extraction protocol for rust spores that yields pure double-stranded DNA molecules with molecular weight of >50 kilo-base pairs (kbp). The isolated DNA is of sufficient purity for PacBio long-read sequencing, but may require additional purification for other sequencing technologies such as Nanopore and 10× Genomics.

Evaluation of Local Wheat Cultivars Susceptibility to infection with Black Stem Rust

International Nuclear Information System (INIS)

Batta, Y.A.

2007-01-01

The present study was conducted to assess the susceptibility of seven local wheat cultivars from Palestine to infection with black stem rust caused by Puccinia graminis f. sp. tritici. Two techniques of disease inoculation were applied during bioassays: global inoculation of entire wheat plants with urediospores and localized inoculation with urediospores and localized inoculation with urediospores on wheat leaf-pieces incubated under humid conditions. Susceptibility of tested cultivars was evaluated according to disease scale based on number and size of typical unredial pustules that appeared after inoculation on entire plants or leaf pieces. Results obtained on bioassay of susceptibility and disease rating on entire plants indicated that Anbar, Kamata and Hetiya safra cultivars were the least susceptible to P. g. tritici infection, whereas Debiya beda cultivar was the most susceptible. The other tested cultivars such as Nab-El-Jama, sawda and Senf 870 were moderately susceptible. On leaf-pieces, Anbar and Kamatat were the least susceptible cultivars, whereas Debiya beda and Nab-El-Jamal were the most susceptible cultivars. The other tested cultivars such as Debiya swada, Senf 870 and Hetiya safra were moderately susceptible. Significant reductions were obtained for the size of unredial postules formed on leaf-pieces when inoculated in an unwounded state compared to the wounded indicating the importance of wounds during inoculation. The global results indicated the possibility of using above method of disease inoculating, scaling and rating for evaluation of wheat cultivars susceptibility for the eventual use in breeding program for resistant varieties in Palestine. (author)

Structure of titanium-doped goethite rust

International Nuclear Information System (INIS)

Nakayama, Takenori; Ishikawa, Tatsuo; Konno, Toyohiko J.

2005-01-01

To investigate the influence of titanium addition on the formation and structure of goethite (α-FeOOH) rust which is one of main corrosion products of weathering steel, the artificially synthesized α-FeOOH rusts were prepared by hydrolysis of aqueous solutions of Fe(III) containing Ti(IV) at different atomic ratios (Ti/Fe) in the range 0-0.1. The obtained rusts particles were observed by TEM. Characterization by XRD, N 2 absorption, Moessbauer spectroscopy was also done. TEM observation revealed that the α-FeOOH rust particle size increased with the increase of Ti/Fe, and that Ti-enriched poorly crystalline particles were formed around the rust particles. XRD confirmed that the crystallite size increased with the increase of Ti/Fe, while the XRD peaks decreased in intensity. Specific surface area obtained by N 2 absorption increased with the increase of Ti/Fe. It is deduced from the obtained results that the addition of Ti(IV) increases the crystallite size of α-FeOOH, and produces double domain particles consisting of the particle core and a porous poorly crystalline shell. It is thought that such unique rust structure produced by titanium addition contributes to the protective properties of rust layer of the weathering steel

Construction and characterization of a full-length cDNA library for the wheat stripe rust pathogen (Puccinia striiformis f. sp. tritici

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Chen Xianming

2007-06-01

Full Text Available Abstract Background Puccinia striiformis is a plant pathogenic fungus causing stripe rust, one of the most important diseases on cereal crops and grasses worldwide. However, little is know about its genome and genes involved in the biology and pathogenicity of the pathogen. We initiated the functional genomic research of the fungus by constructing a full-length cDNA and determined functions of the first group of genes by sequence comparison of cDNA clones to genes reported in other fungi. Results A full-length cDNA library, consisting of 42,240 clones with an average cDNA insert of 1.9 kb, was constructed using urediniospores of race PST-78 of P. striiformis f. sp. tritici. From 196 sequenced cDNA clones, we determined functions of 73 clones (37.2%. In addition, 36 clones (18.4% had significant homology to hypothetical proteins, 37 clones (18.9% had some homology to genes in other fungi, and the remaining 50 clones (25.5% did not produce any hits. From the 73 clones with functions, we identified 51 different genes encoding protein products that are involved in amino acid metabolism, cell defense, cell cycle, cell signaling, cell structure and growth, energy cycle, lipid and nucleotide metabolism, protein modification, ribosomal protein complex, sugar metabolism, transcription factor, transport metabolism, and virulence/infection. Conclusion The full-length cDNA library is useful in identifying functional genes of P. striiformis.

Quantifying airborne dispersal routes of pathogens over continents to safeguard global wheat supply.

Science.gov (United States)

Meyer, M; Cox, J A; Hitchings, M D T; Burgin, L; Hort, M C; Hodson, D P; Gilligan, C A

2017-10-01

Infectious crop diseases spreading over large agricultural areas pose a threat to food security. Aggressive strains of the obligate pathogenic fungus Puccinia graminis f.sp. tritici (Pgt), causing the crop disease wheat stem rust, have been detected in East Africa and the Middle East, where they lead to substantial economic losses and threaten livelihoods of farmers. The majority of commercially grown wheat cultivars worldwide are susceptible to these emerging strains, which pose a risk to global wheat production, because the fungal spores transmitting the disease can be wind-dispersed over regions and even continents 1-11 . Targeted surveillance and control requires knowledge about airborne dispersal of pathogens, but the complex nature of long-distance dispersal poses significant challenges for quantitative research 12-14 . We combine international field surveys, global meteorological data, a Lagrangian dispersion model and high-performance computational resources to simulate a set of disease outbreak scenarios, tracing billions of stochastic trajectories of fungal spores over dynamically changing host and environmental landscapes for more than a decade. This provides the first quantitative assessment of spore transmission frequencies and amounts amongst all wheat producing countries in Southern/East Africa, the Middle East and Central/South Asia. We identify zones of high air-borne connectivity that geographically correspond with previously postulated wheat rust epidemiological zones (characterized by endemic disease and free movement of inoculum) 10,15 , and regions with genetic similarities in related pathogen populations 16,17 . We quantify the circumstances (routes, timing, outbreak sizes) under which virulent pathogen strains such as 'Ug99' 5,6 pose a threat from long-distance dispersal out of East Africa to the large wheat producing areas in Pakistan and India. Long-term mean spore dispersal trends (predominant direction, frequencies, amounts) are

Evaluation of 19,460 Wheat Accessions Conserved in the Indian National Genebank to Identify New Sources of Resistance to Rust and Spot Blotch Diseases

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Jacob, Sherry R.; Srinivasan, Kalyani; Radhamani, J.; Parimalan, R.; Sivaswamy, M.; Tyagi, Sandhya; Yadav, Mamata; Kumari, Jyotisna; Deepali; Sharma, Sandeep; Bhagat, Indoo; Meeta, Madhu; Bains, N. S.; Chowdhury, A. K.; Saha, B. C.; Bhattacharya, P. M.; Kumari, Jyoti; Singh, M. C.; Gangwar, O. P.; Prasad, P.; Bharadwaj, S. C.; Gogoi, Robin; Sharma, J. B.; GM, Sandeep Kumar; Saharan, M. S.; Bag, Manas; Roy, Anirban; Prasad, T. V.; Sharma, R. K.; Dutta, M.; Sharma, Indu; Bansal, K. C.

2016-01-01

A comprehensive germplasm evaluation study of wheat accessions conserved in the Indian National Genebank was conducted to identify sources of rust and spot blotch resistance. Genebank accessions comprising three species of wheat–Triticum aestivum, T. durum and T. dicoccum were screened sequentially at multiple disease hotspots, during the 2011–14 crop seasons, carrying only resistant accessions to the next step of evaluation. Wheat accessions which were found to be resistant in the field were then assayed for seedling resistance and profiled using molecular markers. In the primary evaluation, 19,460 accessions were screened at Wellington (Tamil Nadu), a hotspot for wheat rusts. We identified 4925 accessions to be resistant and these were further evaluated at Gurdaspur (Punjab), a hotspot for stripe rust and at Cooch Behar (West Bengal), a hotspot for spot blotch. The second round evaluation identified 498 accessions potentially resistant to multiple rusts and 868 accessions potentially resistant to spot blotch. Evaluation of rust resistant accessions for seedling resistance against seven virulent pathotypes of three rusts under artificial epiphytotic conditions identified 137 accessions potentially resistant to multiple rusts. Molecular analysis to identify different combinations of genetic loci imparting resistance to leaf rust, stem rust, stripe rust and spot blotch using linked molecular markers, identified 45 wheat accessions containing known resistance genes against all three rusts as well as a QTL for spot blotch resistance. The resistant germplasm accessions, particularly against stripe rust, identified in this study can be excellent potential candidates to be employed for breeding resistance into the background of high yielding wheat cultivars through conventional or molecular breeding approaches, and are expected to contribute toward food security at national and global levels. PMID:27942031

Evaluation of 19,460 Wheat Accessions Conserved in the Indian National Genebank to Identify New Sources of Resistance to Rust and Spot Blotch Diseases.

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Sundeep Kumar

Full Text Available A comprehensive germplasm evaluation study of wheat accessions conserved in the Indian National Genebank was conducted to identify sources of rust and spot blotch resistance. Genebank accessions comprising three species of wheat-Triticum aestivum, T. durum and T. dicoccum were screened sequentially at multiple disease hotspots, during the 2011-14 crop seasons, carrying only resistant accessions to the next step of evaluation. Wheat accessions which were found to be resistant in the field were then assayed for seedling resistance and profiled using molecular markers. In the primary evaluation, 19,460 accessions were screened at Wellington (Tamil Nadu, a hotspot for wheat rusts. We identified 4925 accessions to be resistant and these were further evaluated at Gurdaspur (Punjab, a hotspot for stripe rust and at Cooch Behar (West Bengal, a hotspot for spot blotch. The second round evaluation identified 498 accessions potentially resistant to multiple rusts and 868 accessions potentially resistant to spot blotch. Evaluation of rust resistant accessions for seedling resistance against seven virulent pathotypes of three rusts under artificial epiphytotic conditions identified 137 accessions potentially resistant to multiple rusts. Molecular analysis to identify different combinations of genetic loci imparting resistance to leaf rust, stem rust, stripe rust and spot blotch using linked molecular markers, identified 45 wheat accessions containing known resistance genes against all three rusts as well as a QTL for spot blotch resistance. The resistant germplasm accessions, particularly against stripe rust, identified in this study can be excellent potential candidates to be employed for breeding resistance into the background of high yielding wheat cultivars through conventional or molecular breeding approaches, and are expected to contribute toward food security at national and global levels.

Evaluation of 19,460 Wheat Accessions Conserved in the Indian National Genebank to Identify New Sources of Resistance to Rust and Spot Blotch Diseases.

Science.gov (United States)

Kumar, Sundeep; Archak, Sunil; Tyagi, R K; Kumar, Jagdish; Vk, Vikas; Jacob, Sherry R; Srinivasan, Kalyani; Radhamani, J; Parimalan, R; Sivaswamy, M; Tyagi, Sandhya; Yadav, Mamata; Kumari, Jyotisna; Deepali; Sharma, Sandeep; Bhagat, Indoo; Meeta, Madhu; Bains, N S; Chowdhury, A K; Saha, B C; Bhattacharya, P M; Kumari, Jyoti; Singh, M C; Gangwar, O P; Prasad, P; Bharadwaj, S C; Gogoi, Robin; Sharma, J B; Gm, Sandeep Kumar; Saharan, M S; Bag, Manas; Roy, Anirban; Prasad, T V; Sharma, R K; Dutta, M; Sharma, Indu; Bansal, K C

2016-01-01

A comprehensive germplasm evaluation study of wheat accessions conserved in the Indian National Genebank was conducted to identify sources of rust and spot blotch resistance. Genebank accessions comprising three species of wheat-Triticum aestivum, T. durum and T. dicoccum were screened sequentially at multiple disease hotspots, during the 2011-14 crop seasons, carrying only resistant accessions to the next step of evaluation. Wheat accessions which were found to be resistant in the field were then assayed for seedling resistance and profiled using molecular markers. In the primary evaluation, 19,460 accessions were screened at Wellington (Tamil Nadu), a hotspot for wheat rusts. We identified 4925 accessions to be resistant and these were further evaluated at Gurdaspur (Punjab), a hotspot for stripe rust and at Cooch Behar (West Bengal), a hotspot for spot blotch. The second round evaluation identified 498 accessions potentially resistant to multiple rusts and 868 accessions potentially resistant to spot blotch. Evaluation of rust resistant accessions for seedling resistance against seven virulent pathotypes of three rusts under artificial epiphytotic conditions identified 137 accessions potentially resistant to multiple rusts. Molecular analysis to identify different combinations of genetic loci imparting resistance to leaf rust, stem rust, stripe rust and spot blotch using linked molecular markers, identified 45 wheat accessions containing known resistance genes against all three rusts as well as a QTL for spot blotch resistance. The resistant germplasm accessions, particularly against stripe rust, identified in this study can be excellent potential candidates to be employed for breeding resistance into the background of high yielding wheat cultivars through conventional or molecular breeding approaches, and are expected to contribute toward food security at national and global levels.

Gene discovery in EST sequences from the wheat leaf rust fungus Puccinia triticina sexual spores, asexual spores and haustoria, compared to other rust and corn smut fungi

Science.gov (United States)

2011-01-01

Background Rust fungi are biotrophic basidiomycete plant pathogens that cause major diseases on plants and trees world-wide, affecting agriculture and forestry. Their biotrophic nature precludes many established molecular genetic manipulations and lines of research. The generation of genomic resources for these microbes is leading to novel insights into biology such as interactions with the hosts and guiding directions for breakthrough research in plant pathology. Results To support gene discovery and gene model verification in the genome of the wheat leaf rust fungus, Puccinia triticina (Pt), we have generated Expressed Sequence Tags (ESTs) by sampling several life cycle stages. We focused on several spore stages and isolated haustorial structures from infected wheat, generating 17,684 ESTs. We produced sequences from both the sexual (pycniospores, aeciospores and teliospores) and asexual (germinated urediniospores) stages of the life cycle. From pycniospores and aeciospores, produced by infecting the alternate host, meadow rue (Thalictrum speciosissimum), 4,869 and 1,292 reads were generated, respectively. We generated 3,703 ESTs from teliospores produced on the senescent primary wheat host. Finally, we generated 6,817 reads from haustoria isolated from infected wheat as well as 1,003 sequences from germinated urediniospores. Along with 25,558 previously generated ESTs, we compiled a database of 13,328 non-redundant sequences (4,506 singlets and 8,822 contigs). Fungal genes were predicted using the EST version of the self-training GeneMarkS algorithm. To refine the EST database, we compared EST sequences by BLASTN to a set of 454 pyrosequencing-generated contigs and Sanger BAC-end sequences derived both from the Pt genome, and to ESTs and genome reads from wheat. A collection of 6,308 fungal genes was identified and compared to sequences of the cereal rusts, Puccinia graminis f. sp. tritici (Pgt) and stripe rust, P. striiformis f. sp. tritici (Pst), and poplar

Gene discovery in EST sequences from the wheat leaf rust fungus Puccinia triticina sexual spores, asexual spores and haustoria, compared to other rust and corn smut fungi

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Wynhoven Brian

2011-03-01

Full Text Available Abstract Background Rust fungi are biotrophic basidiomycete plant pathogens that cause major diseases on plants and trees world-wide, affecting agriculture and forestry. Their biotrophic nature precludes many established molecular genetic manipulations and lines of research. The generation of genomic resources for these microbes is leading to novel insights into biology such as interactions with the hosts and guiding directions for breakthrough research in plant pathology. Results To support gene discovery and gene model verification in the genome of the wheat leaf rust fungus, Puccinia triticina (Pt, we have generated Expressed Sequence Tags (ESTs by sampling several life cycle stages. We focused on several spore stages and isolated haustorial structures from infected wheat, generating 17,684 ESTs. We produced sequences from both the sexual (pycniospores, aeciospores and teliospores and asexual (germinated urediniospores stages of the life cycle. From pycniospores and aeciospores, produced by infecting the alternate host, meadow rue (Thalictrum speciosissimum, 4,869 and 1,292 reads were generated, respectively. We generated 3,703 ESTs from teliospores produced on the senescent primary wheat host. Finally, we generated 6,817 reads from haustoria isolated from infected wheat as well as 1,003 sequences from germinated urediniospores. Along with 25,558 previously generated ESTs, we compiled a database of 13,328 non-redundant sequences (4,506 singlets and 8,822 contigs. Fungal genes were predicted using the EST version of the self-training GeneMarkS algorithm. To refine the EST database, we compared EST sequences by BLASTN to a set of 454 pyrosequencing-generated contigs and Sanger BAC-end sequences derived both from the Pt genome, and to ESTs and genome reads from wheat. A collection of 6,308 fungal genes was identified and compared to sequences of the cereal rusts, Puccinia graminis f. sp. tritici (Pgt and stripe rust, P. striiformis f. sp

Slow rusting response of different wheat genotypes against the leaf rust in relation to epidemiological factors in Faisalabad

International Nuclear Information System (INIS)

Khan, M.A.; Haider, M.M.; Hussain, M.; Ahmad, S.

2007-01-01

Wheat genotypes were screened against leaf rust to evaluate slow rusting response. Among one hundred and sixty varieties/lines, 86 showed response to leaf rust while all other remained immune or showed no response. The slow rusting, wheat varieties/ lines displayed 20-40% severity level and these were Maxi-Pak65, Blue silver, Pothohar, Punjab81, Faisalabd-83, Shalimar-88, Kohnoor-83, Pasban-90, Inqilab-91, Uqab-99-94105, Punjab-76, Parwaz-94, HD2169, HD2179, HD2204, HD2285, Lr27+31, LrB, LR17, Lr14A, Lr15 and Yr1-E-1 while the fast rusting varieties/lines that showed severity level up to 90% were WL-711, Morocco, PAK-1, Punjab-85 and Chakwal-86 SA42, SA75, Lr1, Lr2A, Lr2B. Lr23, Lr3KA, Lr3g, Lr10, Lr18, Lr21, Lr24, Yr2-E35 and 95153 respectively. Slow rusting genotypes exhibited low AUDPC (200-400) values while fast rusters displayed high AUDPC (400-1500) values. Leaf rust severity displayed significant correlation with maximum and minimum temperatures, rainfall and sunshine radiation. It was observed that with an increase of these environmental conditions a significant increase in disease severity was recorded

Expression of apoplast-targeted plant defensin MtDef4.2 confers resistance to leaf rust pathogen Puccinia triticina but does not affect mycorrhizal symbiosis in transgenic wheat

Science.gov (United States)

Rust diseases caused by Puccinia spp. pose a major threat to global wheat production. Puccinia triticina (Pt), an obligate basidiomycete biotroph, causes leaf rust disease which incurs yield losses of up to 50% in wheat. Historically, resistant wheat cultivars have been used to control leaf rust, bu...

Comparison of multi- and hyperspectral imaging data of leaf rust infected wheat plants

Science.gov (United States)

Franke, Jonas; Menz, Gunter; Oerke, Erich-Christian; Rascher, Uwe

2005-10-01

In the context of precision agriculture, several recent studies have focused on detecting crop stress caused by pathogenic fungi. For this purpose, several sensor systems have been used to develop in-field-detection systems or to test possible applications of remote sensing. The objective of this research was to evaluate the potential of different sensor systems for multitemporal monitoring of leaf rust (puccinia recondita) infected wheat crops, with the aim of early detection of infected stands. A comparison between a hyperspectral (120 spectral bands) and a multispectral (3 spectral bands) imaging system shows the benefits and limitations of each approach. Reflectance data of leaf rust infected and fungicide treated control wheat stand boxes (1sqm each) were collected before and until 17 days after inoculation. Plants were grown under controlled conditions in the greenhouse and measurements were taken under consistent illumination conditions. The results of mixture tuned matched filtering analysis showed the suitability of hyperspectral data for early discrimination of leaf rust infected wheat crops due to their higher spectral sensitivity. Five days after inoculation leaf rust infected leaves were detected, although only slight visual symptoms appeared. A clear discrimination between infected and control stands was possible. Multispectral data showed a higher sensitivity to external factors like illumination conditions, causing poor classification accuracy. Nevertheless, if these factors could get under control, even multispectral data may serve a good indicator for infection severity.

Derivation of host and pathogen genotypes in the fusiform rust pathosystem on slash pine using a complimentary genetics model and diallel data

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H.E. Stelzel; Robert L. Doudrick; Thomas L. Kubisiak

1997-01-01

Seedlings from 20, full-sib families five-parent slash pine diallel were inoculated using two, single urediniospore-derived cultures of the fusiform rust fungus on two different dates during the 1994 growing season. Presence or absence of fusiform rust galls was recorded for each inoculated seedling at nine months post-inoculation and percent infection levels for each...

Induced resistance to rust disease in lentil

International Nuclear Information System (INIS)

Paul, Amitava; Singh, D.P.

2006-01-01

Considerable yield reduction in lentil is due to rust caused by Uromyces fabae. So far the sources of resistance to rust are available in the small seeded background. There is a need to develop rust resistant/tolerant bold seeded cultivars. Mutations were induced by gamma rays (10 and 15 kR) for incorporating resistance to rust in K-75(Mallika), a high yielding bold seeded, but rust susceptible cultivar at Pantnagar which is the hot spot for this disease. Dry seeds (300) were irradiated for each treatment. In M 1 generation, individual plants from each treatment were selfed and harvested separately which constituted the M 2 generation. In M 2 individual plant progenies were scored following a rating scale of 1 (Free) to 9(highly susceptible). At 15 kR dose, 8 plants were resistant (score 3.0) and 14 plants were tolerant (score 5.0) to rust, while in control and 10 kR populations, all plants were susceptible or highly susceptible having score of 7 or 9, respectively. The M 2 plants segregated in ratio of 1 resistant: 3 susceptible. The progenies of resistant/tolerant M 2 plants were bred true in the M 3 generation suggesting that the resistance to rust is controlled by one recessive gene. (author)

Defeating the Warrior: genetic architecture of triticale resistance against a novel aggressive yellow rust race.

Science.gov (United States)

Losert, Dominik; Maurer, Hans Peter; Leiser, Willmar L; Würschum, Tobias

2017-04-01

Genome-wide association mapping of resistance against the novel, aggressive 'Warrior' race of yellow rust in triticale revealed a genetic architecture with some medium-effect QTL and a quantitative component, which in combination confer high levels of resistance on both leaves and ears. Yellow rust is an important destructive fungal disease in small grain cereals and the exotic 'Warrior' race has recently conquered Europe. The aim of this study was to investigate the genetic architecture of yellow rust resistance in hexaploid winter triticale as the basis for a successful resistance breeding. To this end, a diverse panel of 919 genotypes was evaluated for yellow rust infection on leaves and ears in multi-location field trials and genotyped by genotyping-by-sequencing as well as for known Yr resistance loci. Genome-wide association mapping identified ten quantitative trait loci (QTL) for yellow rust resistance on the leaves and seven of these also for ear resistance. The total genotypic variance explained by the QTL amounted to 44.0% for leaf and 26.0% for ear resistance. The same three medium-effect QTL were identified for both traits on chromosomes 1B, 2B, and 7B. Interestingly, plants pyramiding the resistance allele of all three medium-effect QTL were generally most resistant, but constitute less than 5% of the investigated triticale breeding material. Nevertheless, a genome-wide prediction yielded a higher predictive ability than prediction based on these three QTL. Taken together, our results show that yellow rust resistance in winter triticale is genetically complex, including both medium-effect QTL as well as a quantitative resistance component. Resistance to the novel 'Warrior' race of this fungal pathogen is consequently best achieved by recurrent selection in the field based on identified resistant lines and can potentially be assisted by genomic approaches.

Identification and molecular characterization of a trans-acting small interfering RNA producing locus regulating leaf rust responsive gene expression in wheat (Triticum aestivum L.).

Science.gov (United States)

Dutta, Summi; Kumar, Dhananjay; Jha, Shailendra; Prabhu, Kumble Vinod; Kumar, Manish; Mukhopadhyay, Kunal

2017-11-01

A novel leaf rust responsive ta-siRNA-producing locus was identified in wheat showing similarity to 28S rRNA and generated four differentially expressing ta-siRNAs by phasing which targeted stress responsive genes. Trans-acting-small interfering RNAs (Ta-siRNAs) are plant specific molecules generally involved in development and are also stress responsive. Ta-siRNAs identified in wheat till date are all responsive to abiotic stress only. Wheat cultivation is severely affected by rusts and leaf rust particularly affects grain filling. This study reports a novel ta-siRNA producing locus (TAS) in wheat which is a segment of 28S ribosomal RNA but shows differential expression during leaf rust infestation. Four small RNA libraries prepared from wheat Near Isogenic Lines were treated with leaf rust pathogen and compared with untreated controls. A TAS with the ability to generate four ta-siRNAs by phasing events was identified along with the microRNA TamiR16 as the phase initiator. The targets of the ta-siRNAs included α-gliadin, leucine rich repeat, trans-membrane proteins, glutathione-S-transferase, and fatty acid desaturase among others, which are either stress responsive genes or are essential for normal growth and development of plants. Expression of the TAS, its generated ta-siRNAs, and their target genes were profiled at five different time points after pathogen inoculation of susceptible and resistant wheat isolines and compared with mock-inoculated controls. Comparative analysis of expression unveiled differential and reciprocal relationship as well as discrete patterns between susceptible and resistant isolines. The expression profiles of the target genes of the identified ta-siRNAs advocate more towards effector triggered susceptibility favouring pathogenesis. The study helps in discerning the functions of wheat genes regulated by ta-siRNAs in response to leaf rust.

An overview of sugarcane brown rust in Cuba

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María La O

Full Text Available ABSTRACT: Multiple pathogens affect sugarcane, among them Puccinia melanocephala, the causal agent of brown rust. This disease was first reported in Cuba in 1979 when it was responsible for a severe attack on the main sugarcane variety B4362. The aims of the present study were to give an overview of sugarcane brown rust in Cuba and show the current disease situation in the country. A retrospective analysis regard to sugarcane cultivar composition resistant to brown rust in Cuba was carried out. In addition 154 genotypes, including the most used progenitors in the breeding program and commercial varieties were evaluated under natural infection conditions. The identity of P. melanocephala was verified by Polymerase Chain Reaction (PCR and by sequencing the ITS1 region. After the introduction of P. melanocephala into Cuba, the susceptible variety, B4362, was replaced by Ja60-5 which remained resistant until 1998. Since 2002, a varietal policy supported by a governmental resolution establishing that any single cultivar cannot occupy more than 20 % of the production area for each production company, local area and province, has been applied. Out of the genotypes evaluated, 49 showed resistance to the disease and 35 intermediate behavior, while 39 were susceptible and 31, highly susceptible. P. melanocephala was detected by PCR in all symptomatic samples and its identify confirmed by sequencing the ITS1 region. The adopted measurement together with permanent phytosanitary monitoring and commercial release of resistant or intermediate cultivars succeeded in avoiding any new epidemic. Inoculum pressure was reduced, even on susceptible and highly susceptible varieties since, by resolution, they cannot occupy more than 10 % of the planted area.

Mapping of stripe rust resistance gene in an Aegilops caudate introgression line in wheat and its genetic association with leaf rust resistance.

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Toor, Puneet Inder; Kaur, Satinder; Bansal, Mitaly; Yadav, Bharat; Chhuneja, Parveen

2016-12-01

A pair of stripe rust and leaf rust resistance genes was introgressed from Aegilops caudata, a nonprogenitor diploid species with the CC genome, to cultivated wheat. Inheritance and genetic mapping of stripe rust resistance gene in backcrossrecombinant inbred line (BC-RIL) population derived from the cross of a wheat-Ae. caudata introgression line (IL) T291- 2(pau16060) with wheat cv. PBW343 is reported here. Segregation of BC-RILs for stripe rust resistance depicted a single major gene conditioning adult plant resistance (APR) with stripe rust reaction varying from TR-20MS in resistant RILs signifying the presence of some minor genes as well. Genetic association with leaf rust resistance revealed that two genes are located at a recombination distance of 13%. IL T291-2 had earlier been reported to carry introgressions on wheat chromosomes 2D, 3D, 4D, 5D, 6D and 7D. Genetic mapping indicated the introgression of stripe rust resistance gene on wheat chromosome 5DS in the region carrying leaf rust resistance gene LrAc, but as an independent introgression. Simple sequence repeat (SSR) and sequence-tagged site (STS) markers designed from the survey sequence data of 5DS enriched the target region harbouring stripe and leaf rust resistance genes. Stripe rust resistance locus, temporarily designated as YrAc, mapped at the distal most end of 5DS linked with a group of four colocated SSRs and two resistance gene analogue (RGA)-STS markers at a distance of 5.3 cM. LrAc mapped at a distance of 9.0 cM from the YrAc and at 2.8 cM from RGA-STS marker Ta5DS_2737450, YrAc and LrAc appear to be the candidate genes for marker-assisted enrichment of the wheat gene pool for rust resistance.

Inheritance of resistance to orange rust in sugarcane

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Orange rust, caused by Puccinia kuehnii, is an economically important disease in the Florida sugarcane industry. In this study, orange rust reactions of seedlings in progenies originating from 12 crosses between female and male parents with differing resistance to orange rust (three of each categor...

Identification and characterization of pleiotropic and co-located resistance loci to leaf rust and stripe rust in bread wheat cultivar Sujata.

Science.gov (United States)

Lan, Caixia; Zhang, Yelun; Herrera-Foessel, Sybil A; Basnet, Bhoja R; Huerta-Espino, Julio; Lagudah, Evans S; Singh, Ravi P

2015-03-01

Two new co-located resistance loci, QLr.cim - 1AS/QYr.cim - 1AS and QLr.cim - 7BL/YrSuj , in combination with Lr46 / Yr29 and Lr67/Yr46 , and a new leaf rust resistance quantitative trait loci, conferred high resistance to rusts in adult plant stage. The tall Indian bread wheat cultivar Sujata displays high and low infection types to leaf rust and stripe rust, respectively, at the seedling stage in greenhouse tests. It was also highly resistant to both rusts at adult plant stage in field trials in Mexico. The genetic basis of this resistance was investigated in a population of 148 F5 recombinant inbred lines (RILs) derived from the cross Avocet × Sujata. The parents and RIL population were characterized in field trials for resistance to leaf rust during 2011 at El Batán, and 2012 and 2013 at Ciudad Obregón, Mexico, and for stripe rust during 2011 and 2012 at Toluca, Mexico; they were also characterized three times for stripe rust at seedling stage in the greenhouse. The RILs were genotyped with diversity arrays technology and simple sequence repeat markers. The final genetic map was constructed with 673 polymorphic markers. Inclusive composite interval mapping analysis detected two new significant co-located resistance loci, QLr.cim-1AS/QYr.cim-1AS and QLr.cim-7BL/YrSuj, on chromosomes 1AS and 7BL, respectively. The chromosomal position of QLr.cim-7BL overlapped with the seedling stripe rust resistance gene, temporarily designated as YrSuj. Two previously reported pleiotropic adult plant resistance genes, Lr46/Yr29 and Lr67/Yr46, and a new leaf rust resistance quantitative trait loci derived from Avocet were also mapped in the population. The two new co-located resistance loci are expected to contribute to breeding durable rust resistance in wheat. Closely linked molecular markers can be used to transfer all four resistance loci simultaneously to modern wheat varieties.

Status of white pine blister rust and seed collections in california's high-elevation white pine species

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J. Dunlap

2011-01-01

White pine blister rust (caused by the non-native pathogen Cronartium ribicola) reached northern California about 80 years ago. Over the years its spread southward had been primarily recorded on sugar pine. However, observations on its occurrence had also been reported in several of the higher elevation five-needled white pine species in California. Since the late...

SH1 leaf rust and bacterial halo blight coffee resistances are genetically independent

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Lucas Mateus Rivero Rodrigues

Full Text Available ABSTRACT Coffee resistance to Pseudomonas syringae pv. garcae has been associated to pleiotropic effect of SH1 allele, present in coffee plants resistant to certain races of Hemileia vastatrix, the causal agent of leaf rust, or genetic linkage between resistance alleles to both pathogens. To validate this hypothesis, 63 coffee plants in F2 generation were evaluated for resistance to 2 isolates of H. vastatrix carriers of alleles, respectively, v2, v5 (isolate I/2015 and v1; v2; v5 (isolate II/2015 with the objective to confirm presence of SH1 allele in resistant plants to isolate I/2015. The same coffee plants were evaluated for resistance to a mixture of P. syringae pv. garcae strains highly pathogenic to coffee. Results showed that, among F2 coffee allele SH1 carriers, resistant to isolate I/2015, resistant and susceptible plants to bacterial halo blight were found; the same segregation occurs between F2 homozygous for SH1 allele, susceptible to the same isolate (I/2015 of H. vastatrix. Results also indicate that there is no pleiotropic effect of gene or allele SH1 connection between genes conferring resistance to leaf rust caused by H. vastatrix and bacterial halo blight caused by P. syringae pv. garcae.

Suppression or activation of immune responses by predicted secreted proteins of the soybean rust pathogen Phakopsora pachyrhizi

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Rust fungi, such as Phakopsora pachyrhizi, are major threats to crop production. They form specialized haustoria that are intimately associated with plant cells. These haustoria have roles in acquiring nutrients and secreting effector proteins that manipulate host immune systems. Functional characte...

Genetic differentiation of the wheat leaf rust fungus Puccinia triticina in Pakistan and genetic relationship to other worldwide populations

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Collections of Puccinia triticina, the wheat leaf rust pathogen, were obtained from Pakistan in 2008, 2010, 2011, 2013, and 2014. Collections were also obtained from Bhutan in 2013. Single uredinial isolates were derived and tested for virulence phenotype to 20 lines of Thatcher wheat that differ fo...

Cytogenetics and stripe rust resistance of wheat-Thinopyrum elongatum hybrid derivatives.

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Li, Daiyan; Long, Dan; Li, Tinghui; Wu, Yanli; Wang, Yi; Zeng, Jian; Xu, Lili; Fan, Xing; Sha, Lina; Zhang, Haiqin; Zhou, Yonghong; Kang, Houyang

2018-01-01

Amphidiploids generated by distant hybridization are commonly used as genetic bridge to transfer desirable genes from wild wheat species into cultivated wheat. This method is typically used to enhance the resistance of wheat to biotic or abiotic stresses, and to increase crop yield and quality. Tetraploid Thinopyrum elongatum exhibits strong adaptability, resistance to stripe rust and Fusarium head blight, and tolerance to salt, drought, and cold. In the present study, we produced hybrid derivatives by crossing and backcrossing the Triticum durum-Th. elongatum partial amphidiploid ( Trititrigia 8801, 2 n  = 6 ×  = 42, AABBEE) with wheat cultivars common to the Sichuan Basin. By means of cytogenetic and disease resistance analyses, we identified progeny harboring alien chromosomes and measured their resistance to stripe rust. Hybrid progenies possessed chromosome numbers ranging from 40 to 47 (mean = 42.72), with 40.0% possessing 42 chromosomes. Genomic in situ hybridization revealed that the number of alien chromosomes ranged from 1 to 11. Out of the 50 of analyzed lines, five represented chromosome addition (2 n  = 44 = 42 W + 2E) and other five were chromosome substitution lines (2 n  = 42 = 40 W + 2E). Importantly, a single chromosome derived from wheat- Th. elongatum intergenomic Robertsonian translocations chromosome was occurred in 12 lines. Compared with the wheat parental cultivars ('CN16' and 'SM482'), the majority (70%) of the derivative lines were highly resistant to strains of stripe rust pathogen known to be prevalent in China. The findings suggest that these hybrid-derivative lines with stripe rust resistance could potentially be used as germplasm sources for further wheat improvement.

Yellow Rust Resistance in Advanced Lines and Commercial ...

African Journals Online (AJOL)

The objective of this study was to characterize seedling yellow rust resistance in 21 advanced bread wheat lines and 20 cultivars from Ethiopia. Yellow rust infection types (ITs) produced on test wheat lines and cultivars from nine yellow rust races were compared with ITs produced on standard differential lines that differed ...

An analysis of the risk of introduction of additional strains of the rust puccinia psidii Winter ('Ohi'a Rust) to Hawai'i

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Loope, Lloyd; La Rosa, Anne Marie

2010-01-01

In April 2005, the rust fungus Puccinia psidii (most widely known as guava rust or eucalyptus rust) was found in Hawai'i. This was the first time this rust had been found outside the Neotropics (broadly-defined, including subtropical Florida, where the rust first established in the 1970s). First detected on a nursery-grown 'ohi'a plant, it became known as ''ohi'a rust'in Hawai'i. The rust spread rapidly and by August 2005 had been found throughout the main Hawaiian Islands. The rust probably reached Hawai'i via the live plant trade or via the foliage trade. In Hawai'i, the rust has infected three native plant species and at least eight non-native species. Effects have been substantial on the endangered endemic plant Eugenia koolauensis and the introduced rose apple, Syzygium jambos. Billions of yellow, asexual urediniospores are produced on rose apple, but a complete life cycle (involving sexual reproduction) has not yet been observed. The rust is autoecious (no alternate host known) on Myrtaceae. The strain introduced into Hawai'i is found sparingly on 'ohi'a (Metrosideros polymorpha), the dominant tree of Hawai'i's forests, with sporadic damage detected to date. The introduction of a rust strain that causes widespread damage to 'ohi'a would be catastrophic for Hawai'i's native biodiversity. Most imports of material potentially contaminated with rust are shipped to Hawai'i from Florida and California (from which P. psidii was reported in late 2005 by Mellano, 2006). Florida is known to have multiple strains. The identity of the strain or strains in California is unclear, but one of them is known to infect myrtle, Myrtus communis, a species commonly imported into Hawai'i. It is important to ecosystem conservation and commercial forestry that additional rust strains or genotypes be prevented from establishing in Hawai'i. The purpose of this analysis of risk is to evaluate the need for an interim rule by the Hawai'i Department of Agriculture to regulate plant

Patterns of genomic variation in the poplar rust fungus Melampsora larici-populina identify pathogenesis-related factors

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Antoine ePersoons

2014-09-01

Full Text Available Melampsora larici-populina is a fungal pathogen responsible for foliar rust disease on poplar trees, which causes damage to forest plantations worldwide, particularly in Northern Europe. The reference genome of the isolate 98AG31 was previously sequenced using a whole genome shotgun strategy, revealing a large genome of 101 megabases containing 16,399 predicted genes, which included secreted protein genes representing poplar rust candidate effectors. In the present study, the genomes of 15 isolates collected over the past 20 years throughout the French territory, representing distinct virulence profiles, were characterized by massively parallel sequencing to assess genetic variation in the poplar rust fungus. Comparison to the reference genome revealed striking structural variations. Analysis of coverage and sequencing depth identified large missing regions between isolates related to the mating type loci. More than 611,824 single-nucleotide polymorphism (SNP positions were uncovered overall, indicating a remarkable level of polymorphism. Based on the accumulation of non-synonymous substitutions in coding sequences and the relative frequencies of synonymous and non-synonymous polymorphisms (i.e. PN/PS, we identify candidate genes that may be involved in fungal pathogenesis. Correlation between non-synonymous SNPs in genes encoding secreted proteins and pathotypes of the studied isolates revealed candidate genes potentially related to virulences 1, 6 and 8 of the poplar rust fungus.

Adult plant leaf rust resistance derived from the soft red winter wheat cultivar Caldwell maps to chromosome 3BS

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'Caldwell' is a U.S. soft red winter wheat that has partial, adult plant resistance to the leaf rust pathogen Puccinia triticina. A line of 'Thatcher*2/Caldwell' with adult plant resistance derived from Caldwell was crossed with 'Thatcher' to develop a population of recombinant inbred lines (RILs). ...

Rapid detection of Puccinia triticina causing leaf rust of wheat by PCR and loop mediated isothermal amplification.

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Manjunatha, C; Sharma, Sapna; Kulshreshtha, Deepika; Gupta, Sangeeta; Singh, Kartar; Bhardwaj, Subhash C; Aggarwal, Rashmi

2018-01-01

Leaf rust of wheat caused by Puccinia triticina has significant impact on wheat production worldwide. Effective and quick detection methodologies are required to mitigate yield loss and time constraints associated with monitoring and management of leaf rust of wheat. In the present study, detection of P. triticina has been simplified by developing a rapid, reliable, efficient and visual colorimetric method i.e., loop mediated isothermal amplification of DNA (LAMP). Based on in silico analysis of P. triticina genome, PTS68, a simple sequence repeat was found highly specific to leaf rust fungus. A marker (PtRA68) was developed and its specificity was validated through PCR technique which gave a unique and sharp band of 919 bp in P. triticina pathotypes only. A novel gene amplification method LAMP which enables visual detection of pathogen by naked eye was developed for leaf rust pathogen. A set of six primers was designed from specific region of P. triticina and conditions were optimised to complete the observation process in 60 minutes at 65o C. The assay developed in the study could detect presence of P. triticina on wheat at 24 hpi (pre-symptomatic stage) which was much earlier than PCR without requiring thermal cycler. Sensitivity of LAMP assay developed in the study was 100 fg which was more sensitive than conventional PCR (50 pg) and equivalent to qPCR (100 fg). The protocol developed in the study was utilized for detection of leaf rust infected samples collected from different wheat fields. LAMP based colorimetric detection assay showed sky blue color in positive reaction and violet color in negative reaction after addition of 120 μM hydroxyl napthol blue (HNB) solution to reaction mixture. Similarly, 0.6 mg Ethidium bromide/ml was added to LAMP products, placed on transilluminator to witness full brightness in positive reaction and no such brightness could be seen in negative reaction mixture. Further, LAMP products spread in a ladder like banding pattern in

Historic Rust College: Fulfilling a Mission.

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Hoffman, Carl

1989-01-01

Describes Rust College, a Mississippi college dedicated to educating Blacks from economically and educationally impoverished backgrounds. Discusses the college's financial management, recent fund-raising efforts, building program, and academic programs. Examines the role of the predominantly Black college and Rust's mission to help students…

Living biointerfaces based on non-pathogenic bacteria support stem cell differentiation

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Hay, Jake J.; Rodrigo-Navarro, Aleixandre; Hassi, Karoliina; Moulisova, Vladimira; Dalby, Matthew J.; Salmeron-Sanchez, Manuel

2016-02-01

Lactococcus lactis, a non-pathogenic bacteria, has been genetically engineered to express the III7-10 fragment of human fibronectin as a membrane protein. The engineered L. lactis is able to develop biofilms on different surfaces (such as glass and synthetic polymers) and serves as a long-term substrate for mammalian cell culture, specifically human mesenchymal stem cells (hMSC). This system constitutes a living interface between biomaterials and stem cells. The engineered biofilms remain stable and viable for up to 28 days while the expressed fibronectin fragment induces hMSC adhesion. We have optimised conditions to allow long-term mammalian cell culture, and found that the biofilm is functionally equivalent to a fibronectin-coated surface in terms of osteoblastic differentiation using bone morphogenetic protein 2 (BMP-2) added to the medium. This living bacteria interface holds promise as a dynamic substrate for stem cell differentiation that can be further engineered to express other biochemical cues to control hMSC differentiation.

LEAF WHORL INOCULATION METHOD FOR SCREENING SUGARCANE RUST RESISTANCE

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Technical Abstract: Sugarcane rust diseases, brown rust caused by Puccinia melanocephala, and orange rust caused by P. kuehnii, are agronomically important diseases in Florida. Cultivar resistance is the best means of controlling these diseases. Natural infection has been the primary means of asses...

Bromelain, a cysteine protease from pineapple (Ananas comosus) stem, is an inhibitor of fungal plant pathogens.

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López-García, B; Hernández, M; Segundo, B S

2012-07-01

This study aimed to evaluate the effect of bromelain, a cysteine protease isolated from pineapple (Ananas comosus), on growth of several agronomically important fungal pathogens. Purification of bromelain from pineapple stems was carried out by chromatography techniques, and its antimicrobial activity was tested against the fungal pathogens Fusarium verticillioides, Fusarium oxysporum and Fusarium proliferatum by broth microdilution assay. A concentration of 0.3 μmol l(-1) of bromelain was sufficient for 90% growth inhibition of F. verticillioides. The capability of bromelain to inhibit fungal growth is related to its proteolytic activity. The study demonstrates that stem bromelain exhibits a potent antifungal activity against phytopathogens and suggests its potential use as an effective agent for crop protection. The results support the use of a natural protease that accumulates at high levels in pineapple stems as alternative to the use of chemical fungicides for crop protection. © 2012 The Authors. Letters in Applied Microbiology © 2012 The Society for Applied Microbiology.

Cladosporium cladosporioides and Cladosporium pseudocladosporioides as potential new fungal antagonists of Puccinia horiana Henn., the causal agent of chrysanthemum white rust.

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David Eduardo Torres

Full Text Available Puccinia horiana Hennings, the causal agent of chrysanthemum white rust, is a worldwide quarantine organism and one of the most important fungal pathogens of Chrysanthemum × morifolium cultivars, which are used for cut flowers and as potted plants in commercial production regions of the world. It was previously reported to be controlled by Lecanicillium lecanii, Cladosporium sphaerospermum, C. uredinicola and Aphanocladium album, due to their antagonistic and hyperparasitic effects. We report novel antagonist species on Puccinia horiana. Fungi isolated from rust pustules in a commercial greenhouse from Villa Guerrero, México, were identified as Cladosporium cladosporioides and Cladosporium pseudocladosporioides based upon molecular analysis and morphological characters. The antagonism of C. cladosporioides and C. pseudocladosporioides on chrysanthemum white rust was studied using light and electron microscopy in vitro at the host/parasite interface. Cladosporium cladosporioides and C. pseudocladosporioides grew towards the white rust teliospores and colonized the sporogenous cells, but no direct penetration of teliospores was observed; however, the structure and cytoplasm of teliospores were altered. The two Cladosporium spp. were able to grow on media containing laminarin, but not when chitin was used as the sole carbon source; these results suggest that they are able to produce glucanases. Results from the study indicate that both Cladosporium species had potential as biological control agents of chrysanthemum white rust.

Synoptic climatology of the long-distance dispersal of white pine blister rust II. Combination of surface and upper level conditions

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K. L. Frank; B. W. Geils; L. S. Kalkstein; H. W. Thistle

2008-01-01

An invasive forest pathogen, Cronartium ribicola, white pine blister rust (WPBR), is believed to have arrived in the Sacramento Mountains of south-central New Mexico about 1970. Epidemiological and genetic evidence supports the hypothesis that introduction was the result of long-distance dispersal (LDD) by atmospheric transport from California. This...

Seeing Rust

Science.gov (United States)

2004-01-01

The rust color of the Martian landscape is apparent in this low-resolution thumbnail image taken by the panoramic camera on the Mars Exploration Rover Spirit. This image is part of a larger image currently stored onboard the rover in its memory.

Development of RAPD based markers for wheat rust resistance ...

African Journals Online (AJOL)

Rust diseases are the major cause of low yield of wheat in Pakistan. Wheat breeders all over the world as well as in Pakistan are deriving rust resistance genes from alien species like Triticum ventricosum and introducing them in common wheat (Triticum aestivum). One such example is the introgression of rust resistance ...

The wheat Lr34 multipathogen resistance gene confers resistance to anthracnose and rust in sorghum.

Science.gov (United States)

Schnippenkoetter, Wendelin; Lo, Clive; Liu, Guoquan; Dibley, Katherine; Chan, Wai Lung; White, Jodie; Milne, Ricky; Zwart, Alexander; Kwong, Eunjung; Keller, Beat; Godwin, Ian; Krattinger, Simon G; Lagudah, Evans

2017-11-01

The ability of the wheat Lr34 multipathogen resistance gene (Lr34res) to function across a wide taxonomic boundary was investigated in transgenic Sorghum bicolor. Increased resistance to sorghum rust and anthracnose disease symptoms following infection with the biotrophic pathogen Puccinia purpurea and the hemibiotroph Colletotrichum sublineolum, respectively, occurred in transgenic plants expressing the Lr34res ABC transporter. Transgenic sorghum lines that highly expressed the wheat Lr34res gene exhibited immunity to sorghum rust compared to the low-expressing single copy Lr34res genotype that conferred partial resistance. Pathogen-induced pigmentation mediated by flavonoid phytoalexins was evident on transgenic sorghum leaves following P. purpurea infection within 24-72 h, which paralleled Lr34res gene expression. Elevated expression of flavone synthase II, flavanone 4-reductase and dihydroflavonol reductase genes which control the biosynthesis of flavonoid phytoalexins characterized the highly expressing Lr34res transgenic lines 24-h post-inoculation with P. purpurea. Metabolite analysis of mesocotyls infected with C. sublineolum showed increased levels of 3-deoxyanthocyanidin metabolites were associated with Lr34res expression, concomitant with reduced symptoms of anthracnose. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Wheat Rust Information Resources - Integrated tools and data for improved decision making

DEFF Research Database (Denmark)

Hodson, David; Hansen, Jens Grønbech; Lassen, Poul

giving access to an unprecedented set of data for rust surveys, alternate hosts (barberry), rust pathotypes, trap nurseries and resistant cultivars. Standardized protocols for data collection have permitted the development of a comprehensive data management system, named the Wheat Rust Toolbox....... Integration of the CIMMYT Wheat Atlas and the Genetic Resources Information System (GRIS) databases provides a rich resource on wheat cultivars and their resistance to important rust races. Data access is facilitated via dedicated web portals such as Rust Tracker (www.rusttracker.org) and the Global Rust...

Mapping genes for resistance to stripe rust in spring wheat landrace PI 480035.

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Jinita Sthapit Kandel

Full Text Available Stripe rust caused by Puccinia striiformis Westend. f. sp. tritici Erikks. is an economically important disease of wheat (Triticum aestivum L.. Hexaploid spring wheat landrace PI 480035 was highly resistant to stripe rust in the field in Washington during 2011 and 2012. The objective of this research was to identify quantitative trait loci (QTL for stripe rust resistance in PI 480035. A spring wheat, "Avocet Susceptible" (AvS, was crossed with PI 480035 to develop a biparental population of 110 recombinant inbred lines (RIL. The population was evaluated in the field in 2013 and 2014 and seedling reactions were examined against three races (PSTv-14, PSTv-37, and PSTv-40 of the pathogen under controlled conditions. The population was genotyped with genotyping-by-sequencing and microsatellite markers across the whole wheat genome. A major QTL, QYr.wrsggl1-1BS was identified on chromosome 1B. The closest flanking markers were Xgwm273, Xgwm11, and Xbarc187 1.01 cM distal to QYr.wrsggl1-1BS, Xcfd59 0.59 cM proximal and XA365 3.19 cM proximal to QYr.wrsggl1-1BS. Another QTL, QYr.wrsggl1-3B, was identified on 3B, which was significant only for PSTv-40 and was not significant in the field, indicating it confers a race-specific resistance. Comparison with markers associated with previously reported Yr genes on 1B (Yr64, Yr65, and YrH52 indicated that QYr.wrsggl1-1BS is potentially a novel stripe rust resistance gene that can be incorporated into modern breeding materials, along with other all-stage and adult-plant resistance genes to develop cultivars that can provide durable resistance.

Targeted introgression of a wheat stem rust resistance gene by DNA marker-assisted chromosome engineering.

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Niu, Zhixia; Klindworth, Daryl L; Friesen, Timothy L; Chao, Shiaoman; Jin, Yue; Cai, Xiwen; Xu, Steven S

2011-04-01

Chromosome engineering is a useful strategy for transfer of alien genes from wild relatives into modern crops. However, this strategy has not been extensively used for alien gene introgression in most crops due to low efficiency of conventional cytogenetic techniques. Here, we report an improved scheme of chromosome engineering for efficient elimination of a large amount of goatgrass (Aegilops speltoides) chromatin surrounding Sr39, a gene that provides resistance to multiple stem rust races, including Ug99 (TTKSK) in wheat. The wheat ph1b mutation, which promotes meiotic pairing between homoeologous chromosomes, was employed to induce recombination between wheat chromosome 2B and goatgrass 2S chromatin using a backcross scheme favorable for inducing and detecting the homoeologous recombinants with small goatgrass chromosome segments. Forty recombinants with Sr39 with reduced surrounding goatgrass chromatin were quickly identified from 1048 backcross progenies through disease screening and molecular marker analysis. Four of the recombinants carrying Sr39 with a minimal amount of goatgrass chromatin (2.87-9.15% of the translocated chromosomes) were verified using genomic in situ hybridization. Approximately 97% of the goatgrass chromatin was eliminated in one of the recombinants, in which a tiny goatgrass chromosome segment containing Sr39 was retained in the wheat genome. Localization of the goatgrass chromatin in the recombinants led to rapid development of three molecular markers tightly linked to Sr39. The new wheat lines and markers provide useful resources for the ongoing global effort to combat Ug99. This study has demonstrated great potential of chromosome engineering in genome manipulation for plant improvement.

Effectors from Wheat Rust Fungi Suppress Multiple Plant Defense Responses.

Science.gov (United States)

Ramachandran, Sowmya R; Yin, Chuntao; Kud, Joanna; Tanaka, Kiwamu; Mahoney, Aaron K; Xiao, Fangming; Hulbert, Scot H

2017-01-01

Fungi that cause cereal rust diseases (genus Puccinia) are important pathogens of wheat globally. Upon infection, the fungus secretes a number of effector proteins. Although a large repository of putative effectors has been predicted using bioinformatic pipelines, the lack of available high-throughput effector screening systems has limited functional studies on these proteins. In this study, we mined the available transcriptomes of Puccinia graminis and P. striiformis to look for potential effectors that suppress host hypersensitive response (HR). Twenty small (wheat, confirming its activity in a homologous system. Overall, this study provides the first evidence for the presence of effectors in Puccinia species suppressing multiple plant defense responses.

Contribution to Kinetics of Formation of White Rust on Galvanized Steel

International Nuclear Information System (INIS)

Han, D. J.; Pyun, Su Il; Hahn, Y. D.

1981-01-01

Kinetics of formation of white rust on galvanized steel coated with various chromating solutions was studied. White rust occurs as a mixture of zinc oxide and zinc hydroxide. White rust formation rate was measured with a salt spray test as related to Cr 3+ ion amount, ratio of Cr 3+ to Cr 6+ ion(by weight) and surface roughness of the chromate film. Incubation time of white rust formation increased as the ratio of Cr 3+ to Cr 6+ ion in the chromate film increased. White rust propagation rate decreased as the amount of Cr 3+ ion increased. Surface roughness had no detectable relationship with incubation time and white rust propagation rate. Experimental results showed that kinetics of white rust formation was as follows: chromate film consists of insoluble Cr 3+ ion and soluble Cr 6+ ion, the latter act: as a corrosion inhibitor. Leaching rate of Cr 6+ ion from the film decreases with an increase of the ratio of Cr 3+ to Cr 6+ ion in the chromate film. When Cr 6+ ion is leached from the film, a bare zine layer is exposed to air and discontinuities occur in the film where white rust formation is initiated. Further white rust formation occurs due to destruction of the chromate film by chlorine ion. It is concluded that two stages of white rust formation are present and can be ascribed to Cr 6+ ion leaching and destruction of the chromate film by chlorine ion

Rusted Designs: The New Apron

OpenAIRE

Swindells, Steve; Burcikova, Mila

2013-01-01

Articulated as a practice of design-couture, conceptualized as a project that seeks a sense \\ud of social engagement through research, design and making of everyday ‘common couture’, \\ud Rusted puts craft action in a very close relation with daily (political) or practical life. Rusted \\ud designs collage pre-used fabric and clothing (found, bought or gifted) with new cloth, thus \\ud using items of fabric and clothing from different times, countries and with variety of social \\ud histories. Th...

Rust essentials

CERN Document Server

Balbaert, Ivo

2015-01-01

This book is intended for software developers interested in systems level and application programming, and are looking for a quick entry into using Rust and understanding the core features of the framework. It is assumed that you have a basic understanding of Java, C#, Ruby, Python or JavaScript.

Prediction and analysis of three gene families related to leaf rust (Puccinia triticina) resistance in wheat (Triticum aestivum L.).

Science.gov (United States)

Peng, Fred Y; Yang, Rong-Cai

2017-06-20

The resistance to leaf rust (Lr) caused by Puccinia triticina in wheat (Triticum aestivum L.) has been well studied over the past decades with over 70 Lr genes being mapped on different chromosomes and numerous QTLs (quantitative trait loci) being detected or mapped using DNA markers. Such resistance is often divided into race-specific and race-nonspecific resistance. The race-nonspecific resistance can be further divided into resistance to most or all races of the same pathogen and resistance to multiple pathogens. At the molecular level, these three types of resistance may cover across the whole spectrum of pathogen specificities that are controlled by genes encoding different protein families in wheat. The objective of this study is to predict and analyze genes in three such families: NBS-LRR (nucleotide-binding sites and leucine-rich repeats or NLR), START (Steroidogenic Acute Regulatory protein [STaR] related lipid-transfer) and ABC (ATP-Binding Cassette) transporter. The focus of the analysis is on the patterns of relationships between these protein-coding genes within the gene families and QTLs detected for leaf rust resistance. We predicted 526 ABC, 1117 NLR and 144 START genes in the hexaploid wheat genome through a domain analysis of wheat proteome. Of the 1809 SNPs from leaf rust resistance QTLs in seedling and adult stages of wheat, 126 SNPs were found within coding regions of these genes or their neighborhood (5 Kb upstream from transcription start site [TSS] or downstream from transcription termination site [TTS] of the genes). Forty-three of these SNPs for adult resistance and 18 SNPs for seedling resistance reside within coding or neighboring regions of the ABC genes whereas 14 SNPs for adult resistance and 29 SNPs for seedling resistance reside within coding or neighboring regions of the NLR gene. Moreover, we found 17 nonsynonymous SNPs for adult resistance and five SNPs for seedling resistance in the ABC genes, and five nonsynonymous SNPs for

Mapping of Leaf Rust Resistance Genes and Molecular Characterization of the 2NS/2AS Translocation in the Wheat Cultivar Jagger.

Science.gov (United States)

Xue, Shulin; Kolmer, James A; Wang, Shuwen; Yan, Liuling

2018-04-19

Winter wheat cultivar 'Jagger' was recently found to have an alien chromosomal segment 2NS that has Lr37 , a gene conferring resistance against leaf rust caused by Puccinia triticina The objective of this study was to map and characterize the gene(s) for seedling leaf rust resistance in Jagger. The recombinant inbred line (RIL) population of Jagger × '2174' was inoculated with leaf rust pathogen THBJG and BBBDB, and evaluated for infection type (IT) response. A major quantitative trait locus (QTL) for THBJG and BBBDB was coincidently mapped to chromosome arm 2AS, and the QTL accounted for 56.6% - 66.2% of total phenotypic variation in infection type (IT) response to THBJG, and 72.1% - 86.9% to BBBDB. The causal gene for resistance to these rust races was mapped to the 2NS segment in Jagger. The 2NS segment was located in a region of approximately 27.8 Mb starting from the telomere of chromosome arm 2AS, based on the sequences of the A genome in tetraploid wheat. The Lr17a gene on chromosome arm 2AS was delimited to 3.1 Mb in the genomic region, which was orthologous to the 2NS segment. Therefore, the Lr37 gene in the 2NS segment can be pyramided with other effective resistance genes, rather than Lr17a in wheat, to improve resistance to rust diseases. Copyright © 2018, G3: Genes, Genomes, Genetics.

Genetic and environmental variation in rust frequency on mature mountain birch trees

Energy Technology Data Exchange (ETDEWEB)

Elamo, Pirjo; Saloniemi, Irma; Helander, M.L.; Neuvonen, Seppo [Turku Univ. (Finland). Dept. of Biology) and (Kevo Subarctic Research Inst., Turku (Finland)

2000-07-01

This study investigated genetic and environmental variation in the frequency of birch rust, the most important leaf disease of birch species, The same half-sib families of mature mountain birch trees were studied in two areas corresponding to their natural growing habitats over 3 yrs. The frequency of birch rust was examined both in the field and from detached leaves inoculated in the laboratory. The frequency of birch rust varied among the mountain birch families. However, the heritability of birch rust resistance was found to be fairly low, with the heritability of naturally occurring birch rust varying between 0.27 and 0.41. The frequency of birch rust varied highly between the two study areas and among study years. Nevertheless, the relative frequency of birch rust among tree individuals and tree families remained similar and as a result no notable genotype x environment interaction was observed. The field and in vitro results differed with respect to the ranking of birch families by birch rust resistance.

Host-induced silencing of essential genes in Puccinia triticina through transgenic expression of RNAi sequences reduces severity of leaf rust infection in wheat.

Science.gov (United States)

Panwar, Vinay; Jordan, Mark; McCallum, Brent; Bakkeren, Guus

2018-05-01

Leaf rust, caused by the pathogenic fungus Puccinia triticina (Pt), is one of the most serious biotic threats to sustainable wheat production worldwide. This obligate biotrophic pathogen is prevalent worldwide and is known for rapid adaptive evolution to overcome resistant wheat varieties. Novel disease control approaches are therefore required to minimize the yield losses caused by Pt. Having shown previously the potential of host-delivered RNA interference (HD-RNAi) in functional screening of Pt genes involved in pathogenesis, we here evaluated the use of this technology in transgenic wheat plants as a method to achieve protection against wheat leaf rust (WLR) infection. Stable expression of hairpin RNAi constructs with sequence homology to Pt MAP-kinase (PtMAPK1) or a cyclophilin (PtCYC1) encoding gene in susceptible wheat plants showed efficient silencing of the corresponding genes in the interacting fungus resulting in disease resistance throughout the T 2 generation. Inhibition of Pt proliferation in transgenic lines by in planta-induced RNAi was associated with significant reduction in target fungal transcript abundance and reduced fungal biomass accumulation in highly resistant plants. Disease protection was correlated with the presence of siRNA molecules specific to targeted fungal genes in the transgenic lines harbouring the complementary HD-RNAi construct. This work demonstrates that generating transgenic wheat plants expressing RNAi-inducing transgenes to silence essential genes in rust fungi can provide effective disease resistance, thus opening an alternative way for developing rust-resistant crops. © 2017 Her Majesty the Queen in Right of Canada. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Painting rusted steel: The role of aluminum phosphosilicate

International Nuclear Information System (INIS)

Roselli, S.N.; Amo, B. del; Carbonari, R.O.; Di Sarli, A.R.; Romagnoli, R.

2013-01-01

Highlights: •Aluminum phosphosilicate is an acid pigment which could act as mild phosphating agent. •Aluminum phosphosilicate can phosphatize iron oxides on rusted surfaces. •Aluminum phosphosilicate is compatible with acid binders. •Aluminum phosphosilicate could replace chromate in complete painting schemes. •Aluminum phosphosilicate primers improve paints adhesion on rusted surfaces. -- Abstract: Surface preparation is a key factor for the adequate performance of a paint system. The aim of this investigation is to employ a wash-primer to accomplish the chemical conversion of rusted surface when current cleaning operations are difficult to carry out. The active component of the wash-primer was aluminum phosphosilicate whose electrochemical behavior and the composition of the generated protective layer, both, were studied by electrochemical techniques and scanning electron microscopy (SEM), respectively. Primed rusted steel panels were coated with an alkyd system to perform accelerated tests in the salt spray chamber and electrochemical impedance measurements (EIS). These tests were conducted in parallel with a chromate wash primer and the same alkyd system. Results showed that the wash-primer containing aluminum phosphosilicate could be used satisfactorily to paint rusted steel exhibiting a similar performance to the chromate primer

Relationship between sugarcane rust severity and soil properties in louisiana.

Science.gov (United States)

Johnson, Richard M; Grisham, Michael P; Richard, Edward P

2007-06-01

ABSTRACT The extent of spatial and temporal variability of sugarcane rust (Puccinia melanocephala) infestation was related to variation in soil properties in five commercial fields of sugarcane (interspecific hybrids of Saccharum spp., cv. LCP 85-384) in southern Louisiana. Sugarcane fields were grid-soil sampled at several intensities and rust ratings were collected at each point over 6 to 7 weeks. Soil properties exhibited significant variability (coefficients of variation = 9 to 70.1%) and were spatially correlated in 39 of 40 cases with a range of spatial correlation varying from 39 to 201 m. Rust ratings were spatially correlated in 32 of 33 cases, with a range varying from 29 to 241 m. Rust ratings were correlated with several soil properties, most notably soil phosphorus (r = 0.40 to 0.81) and soil sulfur (r = 0.36 to 0.68). Multiple linear regression analysis resulted in coefficients of determination that ranged from 0.22 to 0.73, and discriminant analysis further improved the overall predictive ability of rust models. Finally, contour plots of soil properties and rust levels clearly suggested a link between these two parameters. These combined data suggest that sugarcane growers that apply fertilizer in excess of plant requirements will increase the incidence and severity of rust infestations in their fields.

Host jumps shaped the diversity of extant rust fungi (Pucciniales).

Science.gov (United States)

McTaggart, Alistair R; Shivas, Roger G; van der Nest, Magriet A; Roux, Jolanda; Wingfield, Brenda D; Wingfield, Michael J

2016-02-01

The aim of this study was to determine the evolutionary time line for rust fungi and date key speciation events using a molecular clock. Evidence is provided that supports a contemporary view for a recent origin of rust fungi, with a common ancestor on a flowering plant. Divergence times for > 20 genera of rust fungi were studied with Bayesian evolutionary analyses. A relaxed molecular clock was applied to ribosomal and mitochondrial genes, calibrated against estimated divergence times for the hosts of rust fungi, such as Acacia (Fabaceae), angiosperms and the cupressophytes. Results showed that rust fungi shared a most recent common ancestor with a mean age between 113 and 115 million yr. This dates rust fungi to the Cretaceous period, which is much younger than previous estimations. Host jumps, whether taxonomically large or between host genera in the same family, most probably shaped the diversity of rust genera. Likewise, species diversified by host shifts (through coevolution) or via subsequent host jumps. This is in contrast to strict coevolution with their hosts. Puccinia psidii was recovered in Sphaerophragmiaceae, a family distinct from Raveneliaceae, which were regarded as confamilial in previous studies. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Annotation of a hybrid partial genome of the Coffee Rust (Hemileia vastatrix contributes to the gene repertoire catalogue of the Pucciniales

Directory of Open Access Journals (Sweden)

Marco Aurelio Cristancho

2014-10-01

Full Text Available Coffee leaf rust caused by the fungus Hemileia vastatrix is the most damaging disease to coffee worldwide. The pathogen has recently appeared in multiple outbreaks in coffee producing countries resulting in significant yield losses and increases in costs related to its control. New races/isolates are constantly emerging as evidenced by the presence of the fungus in plants that were previously resistant. Genomic studies are opening new avenues for the study of the evolution of pathogens, the detailed description of plant-pathogen interactions and the development of molecular techniques for the identification of individual isolates. For this purpose we sequenced 8 different H. vastatrix isolates using NGS technologies and gathered partial genome assemblies due to the large repetitive content in the coffee rust hybrid genome; 74.4% of the assembled contigs harbor repetitive sequences. A hybrid assembly of 333Mb was built based on the 8 isolates; this assembly was used for subsequent analyses.Analysis of the conserved gene space showed that the hybrid H. vastatrix genome, though highly fragmented, had a satisfactory level of completion with 91.94% of core protein-coding orthologous genes present. RNA-Seq from urediniospores was used to guide the de novo annotation of the H. vastatrix gene complement. In total, 14,445 genes organized in 3,921 families were uncovered; a considerable proportion of the predicted proteins (73.8% were homologous to other Pucciniales species genomes. Several gene families related to the fungal lifestyle were identified, particularly 483 predicted secreted proteins that represent candidate effector genes and will provide interesting hints to decipher virulence in the coffee rust fungus. The genome sequence of Hva will serve as a template to understand the molecular mechanisms used by this fungus to attack the coffee plant, to study the diversity of this species and for the development of molecular markers to distinguish

Genome-wide identification and characterization of NB-ARC resistant genes in wheat (Triticum aestivum L.) and their expression during leaf rust infection.

Science.gov (United States)

Chandra, Saket; Kazmi, Andaleeb Z; Ahmed, Zainab; Roychowdhury, Gargi; Kumari, Veena; Kumar, Manish; Mukhopadhyay, Kunal

2017-07-01

NB-ARC domain-containing resistance genes from the wheat genome were identified, characterized and localized on chromosome arms that displayed differential yet positive response during incompatible and compatible leaf rust interactions. Wheat (Triticum aestivum L.) is an important cereal crop; however, its production is affected severely by numerous diseases including rusts. An efficient, cost-effective and ecologically viable approach to control pathogens is through host resistance. In wheat, high numbers of resistance loci are present but only few have been identified and cloned. A comprehensive analysis of the NB-ARC-containing genes in complete wheat genome was accomplished in this study. Complete NB-ARC encoding genes were mined from the Ensembl Plants database to predict 604 NB-ARC containing sequences using the HMM approach. Genome-wide analysis of orthologous clusters in the NB-ARC-containing sequences of wheat and other members of the Poaceae family revealed maximum homology with Oryza sativa indica and Brachypodium distachyon. The identification of overlap between orthologous clusters enabled the elucidation of the function and evolution of resistance proteins. The distributions of the NB-ARC domain-containing sequences were found to be balanced among the three wheat sub-genomes. Wheat chromosome arms 4AL and 7BL had the most NB-ARC domain-containing contigs. The spatio-temporal expression profiling studies exemplified the positive role of these genes in resistant and susceptible wheat plants during incompatible and compatible interaction in response to the leaf rust pathogen Puccinia triticina. Two NB-ARC domain-containing sequences were modelled in silico, cloned and sequenced to analyze their fine structures. The data obtained in this study will augment isolation, characterization and application NB-ARC resistance genes in marker-assisted selection based breeding programs for improving rust resistance in wheat.

16 CFR 23.10 - Misuse of “corrosion proof,” “noncorrosive,” “corrosion resistant,” “rust proof,” “rust resistant...

Science.gov (United States)

2010-01-01

... INDUSTRIES § 23.10 Misuse of “corrosion proof,” “noncorrosive,” “corrosion resistant,” “rust proof,” “rust resistant,” etc. (a) It is unfair or deceptive to: (1) Use the terms “corrosion proof,” “noncorrosive... the product will be immune from rust and other forms of corrosion during the life expectancy of the...

Anaerobic Co-Culture of Mesenchymal Stem Cells and Anaerobic Pathogens - A New In Vitro Model System

OpenAIRE

Kriebel, Katja; Biedermann, Anne; Kreikemeyer, Bernd; Lang, Hermann

2013-01-01

BACKGROUND: Human mesenchymal stem cells (hMSCs) are multipotent by nature and are originally isolated from bone marrow. In light of a future application of hMSCs in the oral cavity, a body compartment with varying oxygen partial pressures and an omnipresence of different bacterial species i.e. periodontitis pathogens, we performed this study to gain information about the behavior of hMSC in an anaerobic system and the response in interaction with oral bacterial pathogens. METHODOLOGY/PRINCIP...

Frequency of comandra blister rust infection episodes on lodgepole pine

Science.gov (United States)

William R. Jacobi; Brian W. Geils; Jane E. Taylor

2002-01-01

Comandra blister rust is a damaging canker disease of lodgepole pine in the Central Rocky Mountains. Our knowledge of previous blister rust outbreaks and the effects of weather and climate on rust epidemiology has not been sufficient to explain the frequency and severity of disease outbreaks. Thus, we sought to describe the seasonal and annual frequency and duration of...

Whitebark pine mortality related to white pine blister rust, mountain pine beetle outbreak, and water availability

Science.gov (United States)

Shanahan, Erin; Irvine, Kathryn M.; Thoma, David P.; Wilmoth, Siri K.; Ray, Andrew; Legg, Kristin; Shovic, Henry

2016-01-01

Whitebark pine (Pinus albicaulis) forests in the western United States have been adversely affected by an exotic pathogen (Cronartium ribicola, causal agent of white pine blister rust), insect outbreaks (Dendroctonus ponderosae, mountain pine beetle), and drought. We monitored individual trees from 2004 to 2013 and characterized stand-level biophysical conditions through a mountain pine beetle epidemic in the Greater Yellowstone Ecosystem. Specifically, we investigated associations between tree-level variables (duration and location of white pine blister rust infection, presence of mountain pine beetle, tree size, and potential interactions) with observations of individual whitebark pine tree mortality. Climate summaries indicated that cumulative growing degree days in years 2006–2008 likely contributed to a regionwide outbreak of mountain pine beetle prior to the observed peak in whitebark mortality in 2009. We show that larger whitebark pine trees were preferentially attacked and killed by mountain pine beetle and resulted in a regionwide shift to smaller size class trees. In addition, we found evidence that smaller size class trees with white pine blister rust infection experienced higher mortality than larger trees. This latter finding suggests that in the coming decades white pine blister rust may become the most probable cause of whitebark pine mortality. Our findings offered no evidence of an interactive effect of mountain pine beetle and white pine blister rust infection on whitebark pine mortality in the Greater Yellowstone Ecosystem. Interestingly, the probability of mortality was lower for larger trees attacked by mountain pine beetle in stands with higher evapotranspiration. Because evapotranspiration varies with climate and topoedaphic conditions across the region, we discuss the potential to use this improved understanding of biophysical influences on mortality to identify microrefugia that might contribute to successful whitebark pine conservation

Survey the Effect of Mycorrhiza and Azospirillum of Wheat Cultivars Resistance in Yellow Rust

Directory of Open Access Journals (Sweden)

M. Jiriaie

2017-01-01

-levels (non-inoculated seeds and inoculated seed and wheat cultivars in three levels, Chamran (bread wheat, Dena and Behrang (durum wheat varieties. In this experiment evaluated, to yellow rust disease, the intensity of infection, the average coefficient of infection, type of infection and area under disease progress curve (AUDPC. Infection type and disease severity were also recorded at flag leaf stage using modified Cobb’s scale. First symptoms of yellow rust were observed in middle January of 2013. Analysis of variance was performed using PROC ANOVA of SAS (version 9.1.3, 2004The comparison of the means was done by Duncan test at a probability level of 5 percent. Results and Discussion: Survey on the resistance to yellow rust in wheat cultivars treated with Mycorrhiza and Azospirillum showed that seed inoculation with Azospirillum traits reduced between 10 percent to 13 percent and the use strains of Mycorrhiza fungi intensity of infection 45-51 percent, the average coefficient of infection and AUDPC 74-85 percent respectively for G. intraradices and G. mosseae strains have been reduced compared with control and Chamran cultivar between 40-70 percent showed more Sensitivity to disease from durum varieties. Generally, the lowest of infection intensity (18.33 was obtained from inoculation of C.V Dena seeds with Azospirillum and G. mosseae strain. According to the result, we found yellow rust in all experiment field also the incidence varied between 10-70 percent. Therefore, it is concluded that, given the climatic conditions favorable to the spread of yellow rust, the incidence of yellow rust in the region that have a high degree of pathogenicity. In general the results of this test, mycorrhiza application has a significant role in enhancing wheat resistance to yellow rust. The seed inoculation with Azospirillum although did not have significant role in disease control, but increased at an acceptable level resistance to wheat rust. But the important point was the combined

Incomplete resistance to coffee leaf rust (Hemileia vastatrix)

NARCIS (Netherlands)

Eskes, A.B.

1983-01-01

Incomplete resistance to coffee leaf rust ( Hemileia vastatrix ) may be of value in obtaining durable resistance, which is of great importance for the perennial coffee crop. Methods were developed to assess incomplete resistance to coffee leaf rust by using illustrated scales

Identification and Severity Determination of Wheat Stripe Rust and Wheat Leaf Rust Based on Hyperspectral Data Acquired Using a Black-Paper-Based Measuring Method

Science.gov (United States)

Ruan, Liu; Wang, Rui; Liu, Qi; Ma, Zhanhong; Li, Xiaolong; Cheng, Pei; Wang, Haiguang

2016-01-01

It is important to implement detection and assessment of plant diseases based on remotely sensed data for disease monitoring and control. Hyperspectral data of healthy leaves, leaves in incubation period and leaves in diseased period of wheat stripe rust and wheat leaf rust were collected under in-field conditions using a black-paper-based measuring method developed in this study. After data preprocessing, the models to identify the diseases were built using distinguished partial least squares (DPLS) and support vector machine (SVM), and the disease severity inversion models of stripe rust and the disease severity inversion models of leaf rust were built using quantitative partial least squares (QPLS) and support vector regression (SVR). All the models were validated by using leave-one-out cross validation and external validation. The diseases could be discriminated using both distinguished partial least squares and support vector machine with the accuracies of more than 99%. For each wheat rust, disease severity levels were accurately retrieved using both the optimal QPLS models and the optimal SVR models with the coefficients of determination (R2) of more than 0.90 and the root mean square errors (RMSE) of less than 0.15. The results demonstrated that identification and severity evaluation of stripe rust and leaf rust at the leaf level could be implemented based on the hyperspectral data acquired using the developed method. A scientific basis was provided for implementing disease monitoring by using aerial and space remote sensing technologies. PMID:27128464

Identification and Severity Determination of Wheat Stripe Rust and Wheat Leaf Rust Based on Hyperspectral Data Acquired Using a Black-Paper-Based Measuring Method.

Science.gov (United States)

Wang, Hui; Qin, Feng; Ruan, Liu; Wang, Rui; Liu, Qi; Ma, Zhanhong; Li, Xiaolong; Cheng, Pei; Wang, Haiguang

2016-01-01

It is important to implement detection and assessment of plant diseases based on remotely sensed data for disease monitoring and control. Hyperspectral data of healthy leaves, leaves in incubation period and leaves in diseased period of wheat stripe rust and wheat leaf rust were collected under in-field conditions using a black-paper-based measuring method developed in this study. After data preprocessing, the models to identify the diseases were built using distinguished partial least squares (DPLS) and support vector machine (SVM), and the disease severity inversion models of stripe rust and the disease severity inversion models of leaf rust were built using quantitative partial least squares (QPLS) and support vector regression (SVR). All the models were validated by using leave-one-out cross validation and external validation. The diseases could be discriminated using both distinguished partial least squares and support vector machine with the accuracies of more than 99%. For each wheat rust, disease severity levels were accurately retrieved using both the optimal QPLS models and the optimal SVR models with the coefficients of determination (R2) of more than 0.90 and the root mean square errors (RMSE) of less than 0.15. The results demonstrated that identification and severity evaluation of stripe rust and leaf rust at the leaf level could be implemented based on the hyperspectral data acquired using the developed method. A scientific basis was provided for implementing disease monitoring by using aerial and space remote sensing technologies.

Wheat rusts in the United States in 2016

Science.gov (United States)

In 2016, wheat stripe rust caused by Puccinia striiformis f. sp. graminis was widespread throughout the United States. Cool temperatures and abundant rainfall in the southern Great Plains allowed stripe rust to become widely established and spread throughout the Great Plains and eastern United State...

Incorporation of Monovalent Cations in Sulfate Green Rust

DEFF Research Database (Denmark)

Christiansen, B. C.; Dideriksen, K.; Katz, A.

2014-01-01

Green rust is a naturally occurring layered mixed-valent ferrous-ferric hydroxide, which can react with a range of redox-active compounds. Sulfate-bearing green rust is generally thought to have interlayers composed of sulfate and water. Here, we provide evidence that the interlayers also contain...... with water showed that Na+ and K+ were structurally fixed in the interlayer, whereas Rb+ and Cs+ could be removed, resulting in a decrease in the basal layer spacing. The incorporation of cations in the interlayer opens up new possibilities for the use of sulfate green rust for exchange reactions with both...

Rust fungi on some poaceous weeds of wheat crops in Pakistan

OpenAIRE

NAJAM-UL-SEHAR AFSHAN*; ABDUL REHMAN NIAZI

2013-01-01

The article enlists common poaceous weeds found in wheat crop sand their specific parasitic rust fungi. In this study, four (04) plant taxa of Poaceae infected with rust fungi are collected from different wheat crops grown in different areas of Pakistan. The rust fungi are isolated, characterized and identified. All these host plants are known weeds of wheat crop in Pakistan. This work would help to identify and enlist the potential rust fungi on weeds of wheat crop that could be utilized to ...

Moessbauer Characterization of Rust Obtained in an Accelerated Corrosion Test

International Nuclear Information System (INIS)

Garcia, K. E.; Morales, A. L.; Arroyave, C. E.; Barrero, C. A.; Cook, D. C.

2003-01-01

We have performed drying-humectation cyclical processes (CEBELCOR) on eight A36 low carbon steel coupons in NaCl solutions containing 1x10 -2 M and 1x10 -1 M concentrations. The main purpose of these experiments is to contribute to the understanding of the conditions for akaganeite formation. Additionally, and with the idea to perform a complete characterization of the rust, this work also considers the formation of other iron oxide phases. The corrosion products were characterized by Moessbauer spectroscopy and X-ray diffraction techniques. Gravimetric analysis demonstrates that the coupons presented high corrosion rates. Magnetite/maghemite was common in the rust stuck to the steel surface, whereas akaganeite was present only in traces. In the rust collected from the solutions, i.e., the rust that goes away from the metal surface easily, a magnetite/maghemite was not present and akaganeite showed up in larger quantities. These results support the idea that high concentrations of Cl - ions are required for the akaganeite formation. We concluded that akaganeite is not easily bonded to the rust layer; this may lead to the formation of a less protective rust layer and to higher corrosion rates.

Resistance to rusts (uromyces pisi and u. viciae-fabae) in pea

OpenAIRE

Barilli, Eleonora; Sillero, Josefina C.; Prats, Elena; Rubiales, Diego

2014-01-01

Pea is the second most important food legume crop in the world. Rust is a pea disease widely distributed, particularly in regions with warm, humid weather. Pea rust can be incited by Uromyces viciae-fabae and by U. pisi. U. viciae-fabae prevails in tropical and subtropical regions such as India and China, while U. pisi prevails in temperate regions. Chemical control of rust is possible, but the use of host plant resistance is the most desired means of rust control. In this paper we revise and...

Creation and validation of a simulator for corneal rust ring removal.

Science.gov (United States)

Mednick, Zale; Tabanfar, Reza; Alexander, Ashley; Simpson, Sarah; Baxter, Stephanie

2017-10-01

To create and validate a simulation model for corneal rust ring removal. Rust rings were created on cadaveric eyes with the use of small particles of metal. The eyes were mounted on suction plates at slit lamps and the trainees practiced rust ring removal. An inexperienced cohort of medical students and first year ophthalmology residents (n=11), and an experienced cohort of senior residents and faculty (n=11) removed the rust rings from the eyes with the use of a burr. Rust ring removal was evaluated based on removal time, percentage of rust removed and incidence of corneal perforation. A survey was administered to participants to determine face validity. Time for rust ring removal was longer in the inexperienced group at 187±93 seconds (range of 66-408 seconds), compared to the experienced group at 117±54 seconds (range of 55-240 seconds) (p=0.046). Removal speed was similar between groups, at 4847±4355 pixels/minute and 7206±5181 pixels/minute in the inexperienced and experienced groups, respectively (p=0.26). Removal percentage values were similar between groups, at 61±15% and 69±18% (p=0.38). There were no corneal perforations. 100% (22/22) of survey respondents believed the simulator would be a valuable practice tool, and 89% (17/19) felt the simulation was a valid representation of the clinical correlate. The corneal rust ring simulator presented here is a valid training tool that could be used by early trainees to gain greater comfort level before attempting rust ring removal on a live patient. Copyright © 2017 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

Induced mutations for soybean rust resistance

International Nuclear Information System (INIS)

Smutkupt, S.; Wongpiyasatid, A.; Lamseejan, S.

1983-01-01

Soybean mutation experiments for inducing rust resistance in the cultivars G 8375, Wakashima mutant number 10, Taichung N, S.J.2, S.J.4, BM 50, BM 98, G 8377, G 8586 and G 8587 have been carried out since 1979. Six pods from each of 4438 control and 43,907 M 1 plants were randomly harvested. M 2 seeds of each cultivar of different doses were bulked (M 2 bulk). In addition, 270 good M 1 plants were selected and threshed singly (M 2 single). M 2 -bulk and M 2 -single seeds were advanced to M 3 . Both, M 3 -bulk and M 3 -single plants, together with the remaining M 2 -bulk seeds were screened for rust resistance in the rainy season of 1980 in Nong Hoi Valley (altitude about 1000 m above sea level) and at Mae Joe Station, both in Chiang Mai Province (latitude 18 deg. 31'-19 deg. N). Based on the IWGSR rating system, soybean plants with slow growth of rust were selected from both locations. The results were as follows: Six plants were selected from a total of 2802 control plants, and 115 from a total of 28,834 M 2 and M 3 plants. Further evaluation of these selections for rust resistance will be carried out in the rainy season of 1981 in Nong Hoi Valley, Chiang Mai. (author)

Tracking the footsteps of an invasive plant pathogen: Intercontinental phylogeographic structure of the white-pine-blister-rust fungus, Cronartium ribicola

Science.gov (United States)

Bryce A. Richardson; Mee-Sook Kim; Ned B. Klopfenstein; Yuko Ota; Kwan Soo Woo; Richard C. Hamelin

2009-01-01

Presently, little is known about the worldwide genetic structure, diversity, or evolutionary relationships of the white-pineblister-rust fungus, Cronartium ribicola. A collaborative international effort is underway to determine the phylogeographic relationships among Asian, European, and North American sources of C. ribicola and...

Winnie Rust

African Journals Online (AJOL)

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Om te trek is om jou kortstondig in 'n liminale staat te bevind. Nóg by jou vertrekpunt, nóg by jou uiteindelike bestemming, sonder die geborgenheid wat hierdie twee vaste plekke kwansuis bied. In 'n hele aantal opsigte is Trek van Winnie Rust 'n beskrywing van verskil- lende liminale state. Dit is egter nie 'n reisverhaal met ...

Correlation between RUST assessments of fracture healing to structural and biomechanical properties.

Science.gov (United States)

Cooke, Margaret E; Hussein, Amira I; Lybrand, Kyle E; Wulff, Alexander; Simmons, Erin; Choi, Jeffrey H; Litrenta, Jody; Ricci, William M; Nascone, Jason W; O'Toole, Robert V; Morgan, Elise F; Gerstenfeld, Louis C; Tornetta, Paul

2018-03-01

Radiographic Union Score for Tibia (RUST) and modified RUST (mRUST) are radiographic tools for quantitatively evaluating fracture healing using a cortical scoring system. This tool has high intra-class correlation coefficients (ICCs); however, little evidence has evaluated the scores against the physical properties of bone healing. Closed, stabilized fractures were made in the femora of C3H/HeJ male mice (8-12 week-old) of two dietary groups: A control and a phosphate restricted diet group. Micro-computed tomography (µCT) and torsion testing were carried out at post-operative days (POD) 14, 21, 35, and 42 (n = 10-16) per group time-point. Anteroposterior and lateral radiographic views were constructed from the µCT scans and scored by five raters. The raters also indicated if the fracture were healed. ICCs were 0.71 (mRUST) and 0.63 (RUST). Both RUST scores were positively correlated with callus bone mineral density (BMD) (r = 0.85 and 0.80, p RUST scores positively correlated with callus strength (r = 0.35 and 0.26, p RUST ≥10 and had excellent relationship to structural and biomechanical metrics. Effect of delayed healing due to phosphate dietary restrictions was found at later time points with all mechanical properties (p RUST scores (p > 0.318). Clinical relevance of this study is both RUST scores showed high correlation to physical properties of healing and generally distinguished healed vs. non-healed fractures. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:945-953, 2018. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Identification of leaf rust resistant gene Lr10 in Pakistani wheat ...

African Journals Online (AJOL)

Leaf (brown) rust is the major disease of wheat in Pakistan and other countries. The disease is more effectively controlled when several rust resistance genes are pyramided into a single line. Molecular survey was conducted to screen 25 Pakistan wheat germplasm for the presence of leaf rust resistance gene Lr10 using ...

Influence of Environmental Conditions and Genetic Background of Arabica Coffee (C. arabica L) on Leaf Rust (Hemileia vastatrix) Pathogenesis.

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Toniutti, Lucile; Breitler, Jean-Christophe; Etienne, Hervé; Campa, Claudine; Doulbeau, Sylvie; Urban, Laurent; Lambot, Charles; Pinilla, Juan-Carlos H; Bertrand, Benoît

2017-01-01

Global warming is a major threat to agriculture worldwide. Between 2008 and 2013, some coffee producing countries in South and Central America suffered from severe epidemics of coffee leaf rust (CLR), resulting in high economic losses with social implications for coffee growers. The climatic events not only favored the development of the pathogen but also affected the physiological status of the coffee plant. The main objectives of the study were to evaluate how the physiological status of the coffee plant modified by different environmental conditions impact on the pathogenesis of CLR and to identify indicators of the physiological status able to predict rust incidence. Three rust susceptible genotypes (one inbred line and two hybrids) were grown in controlled conditions with a combination of thermal regime (TR), nitrogen and light intensity close to the field situation before being inoculated with the rust fungus Hemileia vastatrix . It has been demonstrated that a TR of 27-22°C resulted in 2000 times higher sporulation than with a TR of 23-18°C. It has been also shown that high light intensity combined with low nitrogen fertilization modified the CLR pathogenesis resulting in huge sporulation. CLR sporulation was significantly lower in the F1 hybrids than in the inbred line. The hybrid vigor may have reduced disease incidence. Among the many parameters studied, parameters related to photosystem II and photosynthetic electron transport chain components appeared as indicators of the physiological status of the coffee plant able to predict rust sporulation intensity. Taken together, these results show that CLR sporulation not only depends on the TR but also on the physiological status of the coffee plant, which itself depends on agronomic conditions. Our work suggests that vigorous varieties combined with a shaded system and appropriate nitrogen fertilization should be part of an agro-ecological approach to disease control.

Aecidium kalanchoe sp. nov., a new rust on Kalanchoe blossfeldiana (Crassulaceae).

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Hernádez, José R; Aime, M Catherine; Newbry, Brad

2004-07-01

A rust fungus found on cultivars of Kalanchoe blossfeldiana (Crassulaceae) is described as a new species, Aecidium kalanchoe sp. nov., and compared to the other described rusts on members of the Crassulaceae. Only one other rust is known to parasitize Kalanchoe spp. A DNA sequence of A. kalanchoe suggests that the teleomorph is related to Puccinia.

Kinetics of structural rust transformation in environments containing chloride and SO2

International Nuclear Information System (INIS)

Rendon, J. L.; Valencia, A.

2003-01-01

The behaviour of the rusts produced on low carbon steel exposed in industrial atmospheres, at different distances from the sea, was studied by simulating the wetting-drying cycle in a CEBELCOR type apparatus. Coupons electrode potential was monitored and rust layer was analyzed by gravimetric techniques, optical microscopy and Moessbauer spectroscopy. A particular chloride/sulfur ratio in the atmosphere was found, for which there is a particular behaviour in rust formation. For this ratio, corrosion rates were much less than expected. it is postulated a kinetic mechanism for rust layer formation as the origin of this special behavior. An electrode potential similar to that in a weathering steel was observed, this is reflected in the low corrosion rate obtained. The proposed kinetic mechanism for rust formation under these exposure conditions enables new research lines on layer formation and the development of protective rust for industrial marine atmospheres. (Author) 8 refs

Commandra Blister Rust

Science.gov (United States)

David W. Johnson

1986-01-01

Commandra blister rust is a disease of hard pines that is caused by a fungus growing in the inner bark. The fungus (Cronartium commandrae Pk.) has a complex life cycle. It infects hard pines but needs an alternate host, an unrelated plant, to spread from one pine to another.

Weather and Climate Indicators for Coffee Rust Disease

Science.gov (United States)

Georgiou, S.; Imbach, P. A.; Avelino, J.; Anzueto, F.; del Carmen Calderón, G.

2014-12-01

Coffee rust is a disease that has significant impacts on the livelihoods of those who are dependent on the Central American coffee sector. Our investigation has focussed on the weather and climate indicators that favoured the high incidence of coffee rust disease in Central America in 2012 by assessing daily temperature and precipitation data available from 81 weather stations in the INSIVUMEH and ANACAFE networks located in Guatemala. The temperature data were interpolated to determine the corresponding daily data at 1250 farms located across Guatemala, between 400 and 1800 m elevation. Additionally, CHIRPS five day (pentad) data has been used to assess the anomalies between the 2012 and the climatological average precipitation data at farm locations. The weather conditions in 2012 displayed considerable variations from the climatological data. In general the minimum daily temperatures were higher than the corresponding climatology while the maximum temperatures were lower. As a result, the daily diurnal temperature range was generally lower than the corresponding climatological range, leading to an increased number of days where the temperatures fell within the optimal range for either influencing the susceptibility of the coffee plants to coffee rust development during the dry season, or for the development of lesions on the coffee leaves during the wet season. The coffee rust latency period was probably shortened as a result, and farms at high altitudes were impacted due to these increases in minimum temperature. Factors taken into consideration in developing indicators for coffee rust development include: the diurnal temperature range, altitude, the environmental lapse rate and the phenology. We will present the results of our study and discuss the potential for each of the derived weather and climatological indicators to be used within risk assessments and to eventually be considered for use within an early warning system for coffee rust disease.

Coprecipitation of Arsenate and Arsenite with Green Rust Minerals

Science.gov (United States)

The objectives of this experiment were to evaluate the extent and nature of arsenic co-precipitation with green rusts and to examine the influence of arsenic incorporation on the mineralogy of formed solid phases. Stoichiometric green rusts were obtained by coprecipitation of fe...

Glyphosate Control of Orange and Brown Rusts in Glyphosate-Sensitive Sugarcane Cultivars

Science.gov (United States)

Technical Abstract: Brown and orange rust diseases cause substantial yield reductions on sugarcane (Saccharum spp.) in Florida and other regions where sugarcane is grown. Brown rust caused by Puccinia melanocephala Syd. & P. Syd has been present in Florida since 1978 and orange rust caused by Pucci...

Risks associated with the introduction of Pinus contorta in northern Sweden with special attention to Gremmeniella abietina and North American rusts

International Nuclear Information System (INIS)

Witzell, J.

1999-01-01

Sixty years after the first plantings of the North American Pinus contorta in northern Sweden and twenty years after start of the large scale planting programme, extensive epidemics of the native pathogen Gremmeniella abietina were recorded. A period with extremely cool and rainy summers (1984-1987) followed by a mild winter with large amounts of snow, appeared to be an important predisposing factor to the epidemics. There was a strong negative correlation between disease incidence of G. abietina and temperature sum at the site. The most severe attacks by G. abietina occurred in topographic depressions, on flat ground, and on sites where Picea abies was the dominant species of the old stand. The frequency of trees with stem cankers caused by G. abietina increased during the period of the study. Some cankers had fully girdled the stem and some were completely occluded at the end of the study period. A large proportion of wood damaged by G. abietina adversely influenced processability, and reduced the quality of kraft pulp, and should be sorted out and classed as not perfect raw material. G. abietina was found less frequently in regenerations of native Pinus sylvestris than in those of P. contorta. P. sylvestris showed susceptibility to the North American rusts Endocronartium harknessii, Cronartium coleosporioides and Cronartium comandrae. It was especially susceptible to Endocronartium harknessii, even though disease incidence was low in the studied areas. A high susceptibility to Endocronartium harknessii was found in the P. contorta provenances originating from the Yukon, and most frequently used in Sweden. The risk of a recurrence of predisposing weather conditions with subsequent epidemics of G. abietina in healthy P. contorta plantations should be considered, as well as the risk of severe epidemics on less affected plantations of P. sylvestris due to the high inoculum in nearby P. contorta plantations. Also the risk of North American rusts causing severe

Rust Inhibitor And Fungicide For Cooling Systems

Science.gov (United States)

Adams, James F.; Greer, D. Clay

1988-01-01

Mixture of benzotriazole, benzoic acid, and fungicide prevents growth of rust and fungus. Water-based cooling mixture made from readily available materials prevents formation of metallic oxides and growth of fungi in metallic pipes. Coolant remains clear and does not develop thick sludge tending to collect in low points in cooling systems with many commercial rust inhibitors. Coolant compatible with iron, copper, aluminum, and stainless steel. Cannot be used with cadmium or cadmium-plated pipes.

Efficient Use of Historical Data for Genomic Selection: A Case Study of Stem Rust Resistance in Wheat

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J. Rutkoski

2015-03-01

Full Text Available Genomic selection (GS is a methodology that can improve crop breeding efficiency. To implement GS, a training population (TP with phenotypic and genotypic data is required to train a statistical model used to predict genotyped selection candidates (SCs. A key factor impacting prediction accuracy is the relationship between the TP and the SCs. This study used empirical data for quantitative adult plant resistance to stem rust of wheat ( L. to investigate the utility of a historical TP (TP compared with a population-specific TP (TP, the potential for TP optimization, and the utility of TP data when close relative data is available for training. We found that, depending on the population size, a TP was 1.5 to 4.4 times more accurate than a TP, and TP optimization based on the mean of the generalized coefficient of determination or prediction error variance enabled the selection of subsets that led to significantly higher accuracy than randomly selected subsets. Retaining historical data when data on close relatives were available lead to a 11.9% increase in accuracy, at best, and a 12% decrease in accuracy, at worst, depending on the heritability. We conclude that historical data could be used successfully to initiate a GS program, especially if the dataset is very large and of high heritability. Training population optimization would be useful for the identification of TP subsets to phenotype additional traits. However, after model updating, discarding historical data may be warranted. More studies are needed to determine if these observations represent general trends.

Genome-Wide Association Mapping of Crown Rust Resistance in Oat Elite Germplasm.

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Klos, Kathy Esvelt; Yimer, Belayneh A; Babiker, Ebrahiem M; Beattie, Aaron D; Bonman, J Michael; Carson, Martin L; Chong, James; Harrison, Stephen A; Ibrahim, Amir M H; Kolb, Frederic L; McCartney, Curt A; McMullen, Michael; Fetch, Jennifer Mitchell; Mohammadi, Mohsen; Murphy, J Paul; Tinker, Nicholas A

2017-07-01

Oat crown rust, caused by f. sp. , is a major constraint to oat ( L.) production in many parts of the world. In this first comprehensive multienvironment genome-wide association map of oat crown rust, we used 2972 single-nucleotide polymorphisms (SNPs) genotyped on 631 oat lines for association mapping of quantitative trait loci (QTL). Seedling reaction to crown rust in these lines was assessed as infection type (IT) with each of 10 crown rust isolates. Adult plant reaction was assessed in the field in a total of 10 location-years as percentage severity (SV) and as infection reaction (IR) in a 0-to-1 scale. Overall, 29 SNPs on 12 linkage groups were predictive of crown rust reaction in at least one experiment at a genome-wide level of statistical significance. The QTL identified here include those in regions previously shown to be linked with seedling resistance genes , , , , , and and also with adult-plant resistance and adaptation-related QTL. In addition, QTL on linkage groups Mrg03, Mrg08, and Mrg23 were identified in regions not previously associated with crown rust resistance. Evaluation of marker genotypes in a set of crown rust differential lines supported as the identity of . The SNPs with rare alleles associated with lower disease scores may be suitable for use in marker-assisted selection of oat lines for crown rust resistance. Copyright © 2017 Crop Science Society of America.

Genome-wide identification of the SWEET gene family in wheat.

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Gao, Yue; Wang, Zi Yuan; Kumar, Vikranth; Xu, Xiao Feng; Yuan, De Peng; Zhu, Xiao Feng; Li, Tian Ya; Jia, Baolei; Xuan, Yuan Hu

2018-02-05

The SWEET (sugars will eventually be exported transporter) family is a newly characterized group of sugar transporters. In plants, the key roles of SWEETs in phloem transport, nectar secretion, pollen nutrition, stress tolerance, and plant-pathogen interactions have been identified. SWEET family genes have been characterized in many plant species, but a comprehensive analysis of SWEET members has not yet been performed in wheat. Here, 59 wheat SWEETs (hereafter TaSWEETs) were identified through homology searches. Analyses of phylogenetic relationships, numbers of transmembrane helices (TMHs), gene structures, and motifs showed that TaSWEETs carrying 3-7 TMHs could be classified into four clades with 10 different types of motifs. Examination of the expression patterns of 18 SWEET genes revealed that a few are tissue-specific while most are ubiquitously expressed. In addition, the stem rust-mediated expression patterns of SWEET genes were monitored using a stem rust-susceptible cultivar, 'Little Club' (LC). The resulting data showed that the expression of five out of the 18 SWEETs tested was induced following inoculation. In conclusion, we provide the first comprehensive analysis of the wheat SWEET gene family. Information regarding the phylogenetic relationships, gene structures, and expression profiles of SWEET genes in different tissues and following stem rust disease inoculation will be useful in identifying the potential roles of SWEETs in specific developmental and pathogenic processes. Copyright © 2017 Elsevier B.V. All rights reserved.

Molecular mapping and improvement of leaf rust resistance in wheat breeding lines.

Science.gov (United States)

Tsilo, Toi J; Kolmer, James A; Anderson, James A

2014-08-01

Leaf rust, caused by Puccinia triticina, is the most common and widespread disease of wheat (Triticum aestivum) worldwide. Deployment of host-plant resistance is one of the strategies to reduce losses due to leaf rust disease. The objective of this study was to map genes for adult-plant resistance to leaf rust in a recombinant inbred line (RIL) population originating from MN98550-5/MN99394-1. The mapping population of 139 RILs and five checks were evaluated in 2005, 2009, and 2010 in five environments. Natural infection occurred in the 2005 trials and trials in 2009 and 2010 were inoculated with leaf rust. Four quantitative trait loci (QTL) on chromosomes 2BS, 2DS, 7AL, and 7DS were detected. The QTL on 2BS explained up to 33.6% of the phenotypic variation in leaf rust response, whereas the QTL on 2DS, 7AL, and 7DS explained up to 15.7, 8.1, and 34.2%, respectively. Seedling infection type tests conducted with P. triticina races BBBD and SBDG confirmed that the QTL on 2BS and 2DS were Lr16 and Lr2a, respectively, and these genes were expressed in the seedling and field plot tests. The Lr2a gene mapped at the same location as Sr6. The QTL on 7DS was Lr34. The QTL on 7AL is a new QTL for leaf rust resistance. The joint effects of all four QTL explained 74% of the total phenotypic variation in leaf rust severity. Analysis of different combinations of QTL showed that the RILs containing all four or three of the QTL had the lowest average leaf rust severity in all five environments. Deployment of these QTL in combination or with other effective genes will lead to successful control of leaf rust.

Legume breeding for rust resistance: Lessons to learn from the model Medicago truncatula

OpenAIRE

Rubiales, Diego; Castillejo Sánchez, M. Ángeles; Madrid, Eva; Barilli, Eleonora; Rispail, Nicolas

2011-01-01

Rusts are major biotic constraints of legumes worldwide. Breeding for rust resistance is regarded as the most cost efficient method for rust control. However, in contrast to common bean for which complete monogenic resistance exists and is efficiently used, most of the rust resistance reactions described so far in cool season food legumes are incomplete and of complex inheritance. Incomplete resistance has been described in faba bean, pea, chickpea and lentil and several of their associated Q...

Mapping of stripe rust resistance gene in an Aegilops caudata ...

Indian Academy of Sciences (India)

PUNEET INDER TOOR

A pair of stripe rust and leaf rust resistance genes was introgressed from Aegilops caudata, a nonprogenitor diploid species with the CC genome, to cultivated .... infector rows and experimental material with the mixture of uredinospores of Pst ...

A summary of information on the rust Puccinia psidii Winter (guava rust) with emphasis on means to prevent introduction of additional strains to Hawaii

Science.gov (United States)

Loope, Lloyd

2010-01-01

The neotropical rust fungus Puccinia psidii(P. psidii) was originally described from the host common guava in its native Brazil but has been found since on hosts throughout the myrtle family (Myrtaceae), including a dramatic host jump to nonnative Eucalyptus plantations. Most rust fungi are able to live only on a very narrow range of host species. P. psidii is unusual both for having a broad host range and for the intensity of its damage to susceptible young growth. This rust first got a foothold in the United States in Florida more than three decades ago. The U.S. Department of Agriculture (USDA) has since considered it a nonactionable, nonreportable pest. Hawaii and Florida are the only two states with native species in the myrtle family. Over a period of 30 years, this rust has done little damage to any of the scattered native Myrtaceae in Florida, although the host range of the rust has gradually grown to about 30 mostly nonnative species in the family, apparently because of increasing genetic variety of the rust by repeated introductions. However, Florida’s native Myrtaceae are among the roughly 1,100 neotropical species that are largely resistant to P. psidii. The 3,000 species of non-neotropical Myrtaceae of the Pacific, Australia, Asia, and Africa are expected to prove much more vulnerable to P. psidii. Little is known about the genetics or genetic strains of P. psidii, although existing literature shows that there are numerous strains that have differential ability to infect suites of host plants.

DIVERSITY OF PUCCINIA KUEHNII AND P. MELANOCEPHALA CAUSING RUST DISEASES ON BRAZILIAN SUGARCANE

Science.gov (United States)

Sugarcane industry in Brazil suffers yield loss due to brown rust (Puccinia melanocephala) since 1986 and orange rust (P. kuehnii) as recent as 2009. The main control measure for both diseases has been cultivar resistance. Nevertheless, recent onsets of orange rust on previously resistant cultivars ...

Genome-wide association study of rust traits in orchardgrass using SLAF-seq technology.

Science.gov (United States)

Zeng, Bing; Yan, Haidong; Liu, Xinchun; Zang, Wenjing; Zhang, Ailing; Zhou, Sifan; Huang, Linkai; Liu, Jinping

2017-01-01

While orchardgrass ( Dactylis glomerata L.) is a well-known perennial forage species, rust diseases cause serious reductions in the yield and quality of orchardgrass; however, genetic mechanisms of rust resistance are not well understood in orchardgrass. In this study, a genome-wide association study (GWAS) was performed using specific-locus amplified fragment sequencing (SLAF-seq) technology in orchardgrass. A total of 2,334,889 SLAF tags were generated to produce 2,309,777 SNPs. ADMIXTURE analysis revealed unstructured subpopulations for 33 accessions, indicating that this orchardgrass population could be used for association analysis. Linkage disequilibrium (LD) analysis revealed an average r 2 of 0.4 across all SNP pairs, indicating a high extent of LD in these samples. Through GWAS, a total of 4,604 SNPs were found to be significantly ( P  rust trait. The bulk analysis discovered a number of 5,211 SNPs related to rust trait. Two candidate genes, including cytochrome P450, and prolamin were implicated in disease resistance through prediction of functional genes surrounding each high-quality SNP ( P  rust traits based on GWAS analysis and bulk analysis. The large number of SNPs associated with rust traits and these two candidate genes may provide the basis for further research on rust resistance mechanisms and marker-assisted selection (MAS) for rust-resistant lineages.

Investigating the host-range of the rust fungus Puccinia psidii sensu lato across tribes of the family Myrtaceae present in Australia.

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Louise Morin

Full Text Available The exotic rust fungus Puccinia psidii sensu lato was first detected in Australia in April 2010. This study aimed to determine the host-range potential of this accession of the rust by testing its pathogenicity on plants of 122 taxa, representative of the 15 tribes of the subfamily Myrtoideae in the family Myrtaceae. Each taxon was tested in two separate trials (unless indicated otherwise that comprised up to five replicates per taxon and six replicates of a positive control (Syzygium jambos. No visible symptoms were observed on the following four taxa in either trial: Eucalyptus grandis×camaldulensis, E. moluccana, Lophostemon confertus and Sannantha angusta. Only small chlorotic or necrotic flecks without any uredinia (rust fruiting bodies were observed on inoculated leaves of seven other taxa (Acca sellowiana, Corymbia calophylla 'Rosea', Lophostemon suaveolens, Psidium cattleyanum, P. guajava 'Hawaiian' and 'Indian', Syzygium unipunctatum. Fully-developed uredinia were observed on all replicates across both trials of 28 taxa from 8 tribes belonging to the following 17 genera: Agonis, Austromyrtus, Beaufortia, Callistemon, Calothamnus, Chamelaucium, Darwinia, Eucalyptus, Gossia, Kunzea, Leptospermum, Melaleuca, Metrosideros, Syzygium, Thryptomene, Tristania, Verticordia. In contrast, the remaining 83 taxa inoculated, including the majority of Corymbia and Eucalyptus species, developed a broad range of symptoms, often across the full spectrum, from fully-developed uredinia to no visible symptoms. These results were encouraging as they indicate that some levels of genetic resistance to the rust possibly exist in these taxa. Overall, our results indicated no apparent association between the presence or absence of disease symptoms and the phylogenetic relatedness of taxa. It is most likely that the majority of the thousands of Myrtaceae species found in Australia have the potential to become infected to some degree by the rust, although this

Investigating the Host-Range of the Rust Fungus Puccinia psidii sensu lato across Tribes of the Family Myrtaceae Present in Australia

Science.gov (United States)

Morin, Louise; Aveyard, Ruth; Lidbetter, Jonathan R.; Wilson, Peter G.

2012-01-01

The exotic rust fungus Puccinia psidii sensu lato was first detected in Australia in April 2010. This study aimed to determine the host-range potential of this accession of the rust by testing its pathogenicity on plants of 122 taxa, representative of the 15 tribes of the subfamily Myrtoideae in the family Myrtaceae. Each taxon was tested in two separate trials (unless indicated otherwise) that comprised up to five replicates per taxon and six replicates of a positive control (Syzygium jambos). No visible symptoms were observed on the following four taxa in either trial: Eucalyptus grandis×camaldulensis, E. moluccana, Lophostemon confertus and Sannantha angusta. Only small chlorotic or necrotic flecks without any uredinia (rust fruiting bodies) were observed on inoculated leaves of seven other taxa (Acca sellowiana, Corymbia calophylla ‘Rosea’, Lophostemon suaveolens, Psidium cattleyanum, P. guajava ‘Hawaiian’ and ‘Indian’, Syzygium unipunctatum). Fully-developed uredinia were observed on all replicates across both trials of 28 taxa from 8 tribes belonging to the following 17 genera: Agonis, Austromyrtus, Beaufortia, Callistemon, Calothamnus, Chamelaucium, Darwinia, Eucalyptus, Gossia, Kunzea, Leptospermum, Melaleuca, Metrosideros, Syzygium, Thryptomene, Tristania, Verticordia. In contrast, the remaining 83 taxa inoculated, including the majority of Corymbia and Eucalyptus species, developed a broad range of symptoms, often across the full spectrum, from fully-developed uredinia to no visible symptoms. These results were encouraging as they indicate that some levels of genetic resistance to the rust possibly exist in these taxa. Overall, our results indicated no apparent association between the presence or absence of disease symptoms and the phylogenetic relatedness of taxa. It is most likely that the majority of the thousands of Myrtaceae species found in Australia have the potential to become infected to some degree by the rust, although this wide

From the root to the stem: interaction between the biocontrol root endophyte Pseudomonas fluorescens PICF7 and the pathogen Pseudomonas savastanoi NCPPB 3335 in olive knots

Science.gov (United States)

Maldonado-González, M Mercedes; Prieto, Pilar; Ramos, Cayo; Mercado-Blanco, Jesús

2013-01-01

Olive knot disease, caused by Pseudomonas savastanoi pv. savastanoi, is one of the most important biotic constraints for olive cultivation. Pseudomonas fluorescens PICF7, a natural colonizer of olive roots and effective biological control agent (BCA) against Verticillium wilt of olive, was examined as potential BCA against olive knot disease. Bioassays using in vitro-propagated olive plants were carried out to assess whether strain PICF7 controlled knot development either when co-inoculated with the pathogen in stems or when the BCA (in roots) and the pathogen (in stems) were spatially separated. Results showed that PICF7 was able to establish and persist in stem tissues upon artificial inoculation. While PICF7 was not able to suppress disease development, its presence transiently decreased pathogen population size, produced less necrotic tumours, and sharply altered the localization of the pathogen in the hyperplasic tissue, which may pose epidemiological consequences. Confocal laser scanning microscopy combined with fluorescent tagging of bacteria revealed that when PICF7 was absent the pathogen tended to be localized at the knot surface. However, presence of the BCA seemed to confine P. savastanoi at inner regions of the tumours. This approach has also enabled to prove that the pathogen can moved systemically beyond the hypertrophied tissue. PMID:23425069

Essential Oils for Alternative Teak Rust Control

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Pedro Raymundo Argüelles Osorio

2018-03-01

Full Text Available ABSTRACT The objectives of this study were to evaluate the effect of lemon grass, citronella grass, Mexican-tea and noni essential oils on urediniospore germination of Olivea neotectonae , the agent responsible for rust in Teak (Tectona grandis L.f.; to evaluate the phytotoxic effect of these essential oils on teak seedlings; and to evaluate the use of essential oils to control rust in teak plants when preventively and curatively applied. We found that the noni and lemon grass essential oils inhibited 100% of urediniospore germination. On the other hand, the essential oils from noni and lemon grass caused phytotoxicity when applied to seedlings at concentrations of 2000 and 1500 μL L-1, respectively. The major constituents found in lemon grass essential oil were Geranial and Neral, while Octanoic Acid was found in noni oil. Lower values in the area below the rust progress curve were observed with the preventive application of lemon grass and noni essential oils.

Draft whole genome sequence of groundnut stem rot fungus Athelia rolfsii revealing genetic architect of its pathogenicity and virulence.

Science.gov (United States)

Iquebal, M A; Tomar, Rukam S; Parakhia, M V; Singla, Deepak; Jaiswal, Sarika; Rathod, V M; Padhiyar, S M; Kumar, Neeraj; Rai, Anil; Kumar, Dinesh

2017-07-13

Groundnut (Arachis hypogaea L.) is an important oil seed crop having major biotic constraint in production due to stem rot disease caused by fungus, Athelia rolfsii causing 25-80% loss in productivity. As chemical and biological combating strategies of this fungus are not very effective, thus genome sequencing can reveal virulence and pathogenicity related genes for better understanding of the host-parasite interaction. We report draft assembly of Athelia rolfsii genome of ~73 Mb having 8919 contigs. Annotation analysis revealed 16830 genes which are involved in fungicide resistance, virulence and pathogenicity along with putative effector and lethal genes. Secretome analysis revealed CAZY genes representing 1085 enzymatic genes, glycoside hydrolases, carbohydrate esterases, carbohydrate-binding modules, auxillary activities, glycosyl transferases and polysaccharide lyases. Repeat analysis revealed 11171 SSRs, LTR, GYPSY and COPIA elements. Comparative analysis with other existing ascomycotina genome predicted conserved domain family of WD40, CYP450, Pkinase and ABC transporter revealing insight of evolution of pathogenicity and virulence. This study would help in understanding pathogenicity and virulence at molecular level and development of new combating strategies. Such approach is imperative in endeavour of genome based solution in stem rot disease management leading to better productivity of groundnut crop in tropical region of world.

Use of gamma radiation for inducing rust resistance in soybean

International Nuclear Information System (INIS)

Smutkupt, Sumit; Wongpiyasatid, Arunee; Lamseejan, Siranut; Naritoom, Kruik

1982-01-01

Experiments on induced mutations for rust resistance in 11 soybean cultivars were started in the rainy season of 1979. M 1 seeds were grown at Farm Suwan, Pak Chong, Nakorn Rajchasima Province. Six plods from each of 4,438 control and 43,907 M 1 plants were randomly harvested. M 2 seeds of each cultivar of different doses were bulked. In addition, 270 good M 1 plants were selected and threshed singly. M 2 -bulk and M 2 -single seeds were advanced to M 3 . Both of M 3 -bulk and M 3 -single plants together with M 2 -bulk plants derived from remnant M 2 seeds were screened for rust resistance in the rainy season of 1980. The IWGSR rust rating system was used. Based on the slow growth of rust reaction on the plant (323,333) compared with the average IWGSR rust rating notation of the rates (343) in the same row, 121 plants were selected. Among them, six were selected from a total of 2802 control plants, and 115 from a total of 28,834 M 2 and M 3 plants. Seeds of each selection harvested. Only 88 lines of M 4 and M 5 were available for further rust evaluation in the rainy season of 1981. The results were as follows: At 77 days after planting, 82 selected lines were rated 333, 323 in comparison with 87 out of 137 rows of control S.J.1, S.J.2, S.J.4 and T.K.5 were rated 343. At 86 days after planting, most of the selections reached the diseased level 343. However, six lines which were derived from G8586 were still rated 333. In addition, a plant with slow growth of rust (323) from Taichung N No. 81-1-032 was selected. The six selected lines having characteristics of slow growth of rust reaction on the plants will be further tested. The high yielding selections among 82 selected lines having low percentage of shrivelled seeds will be used for further yield evaluation in the rainy season of 1982

Molecular mapping of a sunflower rust resistance gene from HAR6.

Science.gov (United States)

Bulos, Mariano; Ramos, María L; Altieri, Emiliano; Sala, Carlos A

2013-03-01

Sunflower rust, caused by Puccinia helianthi Schw., can result in significant yield losses in cultivated sunflower (Helianthus annuus L. var. macrocarpus Ckll.). HAR6 is a germplasm population resistant to most predominant rust races. The objectives of this study were to map the resistance factor present in HAR6 (R HAR6 ), and to provide and validate molecular tools for the identification of this gene for marker assisted selection purposes. Virulence reaction of seedlings for the F2 population and F2:3 families suggested that a single dominant gene confers rust resistance in HAR6-1, a selected rust resistance line from the original population. Genetic mapping with eight markers covered 97.4 cM of genetic distance on linkage group 13 of the sunflower consensus map. A co-dominant marker ZVG61 is the closest marker distal to R HAR6 at a genetic distance of 0.7 cM, while ORS581, a dominant marker linked in the coupling phase, is proximal to R HAR6 at a genetic distance of 1.5 cM. Validation of these markers was assessed by converting a susceptible line into a rust resistant isoline by means of marker assisted backcrossing. The application of these results to assist the breeding process and to design new strategies for rust control in sunflower is discussed.

Leaf and stripe rust resistance among Ethiopian grown wheat ...

African Journals Online (AJOL)

The result indicated that 20 varieties and lines harbor resistance to the leaf rust and 26 to the stripe rust pathotypes showing infection types <2+. Twelve bread wheat varieties and lines (Et-13 A2, HAR 1407 [Tusie], HAR 1775 [Tura], HAR 1920, HAR 2192, HAR 2534, HAR 2536, HAR 2561, HAR 2563 and three durum lines ...

White pines, blister rust, and management in the Southwest

Science.gov (United States)

D. A. Conklin; M Fairweather; D Ryerson; B Geils; D Vogler

2009-01-01

White pines in New Mexico and Arizona are threatened by the invasive disease white pine blister rust, Cronartium ribicola. Blister rust is already causing severe damage to a large population of southwestern white pine in the Sacramento Mountains of southern New Mexico. Recent detection in northern and western New Mexico suggests that a major expansion of the...

Interacting genes in the pine-fusiform rust forest pathosystem

Science.gov (United States)

H.V. Amerson; T.L. Kubisiak; S.A. Garcia; G.C. Kuhlman; C.D. Nelson; S.E. McKeand; T.J. Mullin; B. Li

2005-01-01

Fusiform rust (FR) disease of pines, caused by Cronartium quercuum f.sp. fusiforme (Cqf), is the most destructive disease in pine plantations of the southern U. S. The NCSU fusiform rust program, in conjunction with the USDA-Forest Service in Saucier, MS and Athens, GA, has research underway to elucidate some of the genetic interactions in this...

Identification of Green Rust in Groundwater

DEFF Research Database (Denmark)

Christiansen, Bo C.; Balic Zunic, Tonci; Dideriksen, Knud

2009-01-01

to air. In this paper, we present a sampling method for capturing green rust so it is not oxidized. We then we used the method to identify the compound in a groundwater sample taken below the water table from fractures in granite. X-ray diffraction patterns were weak, but clearly identical to those......Green rust, a family of Fe(II),Fe(III) layered double hydroxides, is believed to be present in environments close to the Fe(II)/Fe(III) transition zone. Attempts to identify members of this family in nature have proven difficult because the material is oxidized after only a few minutes exposure...

Structure and Charge Hopping Dynamics in Green Rust

International Nuclear Information System (INIS)

Wander, Matthew C.; Rosso, Kevin M.; Schoonen, Martin A.

2007-01-01

Green rust is a family of mixed-valent iron phases formed by a number of abiotic and biotic processes under alkaline suboxic conditions. Due to its high Fe2+ content, green rust is a potentially important phase for pollution remediation by serving as a powerful electron donor for reductive transformation. However, mechanisms of oxidation of this material are poorly understood. An essential component of the green rust structure is a mixed-valent brucite-like Fe(OH)2 sheet comprised of a two dimensional network of edge-sharing iron octahedra. Room temperature Mossbauer spectra show a characteristic signature for intermediate valence on the iron atoms in this sheet, indicative of a Fe2+-Fe3+ valence interchange reaction faster than approximately 107s-1. Using Fe(OH)2 as structural analogue for reduced green rust, we performed Hartree-Fock calculations on periodic slab models and cluster representations to determine the structure and hopping mobility of Fe3+ hole polarons in this material, providing a first principles assessment of the Fe2+-Fe3+ valence interchange reaction rate. The calculations show that among three possible symmetry unique iron-to-iron hops within a sheet, a hop to next-nearest neighbors at an intermediate distance of 5.6Angstroms is the fastest. The predicted rate is on the order of 1012 s-1 consistent the Mossbauer-based constraint. All other possibilities, including hopping across interlayer spaces, are predicted to be slower than 107s-1. Collectively, the findings suggest the possibility of hole self-diffusion along sheets as a mechanism for regeneration of lattice Fe2+ sites, consistent with previous experimental observations of edge-inward progressive oxidation of green rust.

Characteristics of superior soybean breeding lines tolerance to rust (Phakopsora pachyrhizi Syd.

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Alfi Inayati

2016-04-01

Full Text Available Soybean rust caused by Phakopsora pachyrhizi is one of the most important diseases which limits soybean production. The aim of this study was to evaluate the resistance of 28 superior soybean lines and their tolerance to rust. The study was conducted at a screen house and arranged in a completely randomized design (CRD; three replications. All genotypes tested were artificially inoculated with P. pachyrhizi, and a set of un-inoculated genotypes was planted as a comparison. Number of pustules was recorded weekly, and resistant criteria was rated based on the International working group on soybean rust IWGSR method. Lesion color (LC, sporulation level (SL, number of uredia (NoU, frequency of pustule which had uredia, and yield were also recorded. Among 28 genotypes tested, only one was categorized as resistant and 2 genotypes were susceptible. Resistant genotypes had few pustules, lower AUDPC values, low disease severity, and Reddish Brown lesion type. Soybean rust affected yield components, i.e. number of intact pods and yield per plant. Yield loses due to rust in this study varied from 5-89%, and the average was 51%. The set of lines from Tanggamus pedigree showed more resistant to rust but less tolerant compared to Sinabung pedigree.How to CiteInayati, A., & Yusnawan, E. (2016. Characteristics of superior soybean breeding lines tolerancet to rust (Phakopsora pachyrhizi Syd.. Biosaintifika: Journal of Biology & Biology Education, 8(1, 47-55.

Control Of Rust Disease In Irradiated Vicia Faba By Using Safe Alternative Methods

International Nuclear Information System (INIS)

Ahmed, B.M.; Helal, I.M.; Mohamed, G.A.

2013-01-01

Infection of Vicia faba with Uromyces viciae-fabae causes significant decrease in growth and total nitrogen content and increase in the phenolic compounds. The study was carried out to investigate the effects of chemicals used as drench application in soil (e.g. saccharin), biotic agents (e.g. Bacillus subtilis) and artificial essential oils (e.g. rosemary) in irradiated (0, 5, 10, 15 Gy) broad bean Vicia faba on the rust fungus Uromyces viciae-fabae. Bacillus subtilis was inoculated to beans at the third leaf then saccharin (5 mM/l) was used as drench application in the soil and the essential oil was used for foliar application at concentrations 0, 500, 1000 and 1500 ppm. All treatments gave positive results to control the disease but differ in the mechanism of action. The control of the disease with saccharin application may be due to the formation of antimicrobial components (wyrone acid) by plant tissues and increase with increasing the concentration of saccharin. In case of using the essential oil, the affect on the microbe was directly observed within 28 h because the oil affect the permeability of cell membrane of the pathogen but in case of Bacillus, it acts as biological control agent induced resistance of plant by affecting the activity of antioxidant enzymes; peroxidase and chitinase. Saccharin and spore suspension induce systemic protection to rust infection after 72 and 96 hours. The disease index and the phenolic compounds were determined because they play important role in the systemic protection of rust disease 96 h after application. The results showed that the phytoalexin wyerone acid was formed in case of biotic agent (Bacillus subtilis) and the chemical (saccharin) but did not form in case of essential oil (rosemary)

High-throughput genotyping-by-sequencing facilitates molecular tagging of a novel rust resistance gene, R 15 , in sunflower (Helianthus annuus L.).

Science.gov (United States)

Ma, G J; Song, Q J; Markell, S G; Qi, L L

2018-03-21

A novel rust resistance gene, R 15 , derived from the cultivated sunflower HA-R8 was assigned to linkage group 8 of the sunflower genome using a genotyping-by-sequencing approach. SNP markers closely linked to R 15 were identified, facilitating marker-assisted selection of resistance genes. The rust virulence gene is co-evolving with the resistance gene in sunflower, leading to the emergence of new physiologic pathotypes. This presents a continuous threat to the sunflower crop necessitating the development of resistant sunflower hybrids providing a more efficient, durable, and environmentally friendly host plant resistance. The inbred line HA-R8 carries a gene conferring resistance to all known races of the rust pathogen in North America and can be used as a broad-spectrum resistance resource. Based on phenotypic assessments of 140 F 2 individuals derived from a cross of HA 89 with HA-R8, rust resistance in the population was found to be conferred by a single dominant gene (R 15 ) originating from HA-R8. Genotypic analysis with the currently available SSR markers failed to find any association between rust resistance and any markers. Therefore, we used genotyping-by-sequencing (GBS) analysis to achieve better genomic coverage. The GBS data showed that R 15 was located at the top end of linkage group (LG) 8. Saturation with 71 previously mapped SNP markers selected within this region further showed that it was located in a resistance gene cluster on LG8, and mapped to a 1.0-cM region between three co-segregating SNP makers SFW01920, SFW00128, and SFW05824 as well as the NSA_008457 SNP marker. These closely linked markers will facilitate marker-assisted selection and breeding in sunflower.

The Brachypodium-Puccinia graminis system: Solving a puzzle to uncover the underlying mechanisms of non-host resistance and plant immunity

Science.gov (United States)

Brachypodium distachyon is regarded as non-host to the causal agent of stem rust in wheat and barley, P. graminis f. sp. tritici (Pgt), and a near-host to the pathogens of forage grasses, P. graminis f. sp. lolii (Pgl) and P. graminis f. sp. phlei-pratensis (Pgp). Given the devastating effect of ste...

Author Details

African Journals Online (AJOL)

Fininsa, C. Vol 17, No 4 (2009) - Articles Evaluation of pathogenic isolates in Ethiopia for the control of chocolate spot in Faba bean. Abstract PDF · Vol 15, No 1 (2007) - Articles Sources of stem rust resistance in Ethiopian tetraploid wheat accessions. Abstract PDF · Vol 19, No 3 (2011) - Articles Potential antagonistic fungal ...

Proximal Sensing of Plant-Pathogen Interactions in Spring Barley with Three Fluorescence Techniques

Directory of Open Access Journals (Sweden)

Georg Leufen

2014-06-01

Full Text Available In the last years fluorescence spectroscopy has come to be viewed as an essential approach in key research fields of applied plant sciences. However, the quantity and particularly the quality of information produced by different equipment might vary considerably. In this study we investigate the potential of three optical devices for the proximal sensing of plant-pathogen interactions in four genotypes of spring barley. For this purpose, the fluorescence lifetime, the image-resolved multispectral fluorescence and selected indices of a portable multiparametric fluorescence device were recorded at 3, 6, and 9 days after inoculation (dai from healthy leaves as well as from leaves inoculated with powdery mildew (Blumeria graminis or leaf rust (Puccinia hordei. Genotype-specific responses to pathogen infections were revealed already at 3 dai by higher fluorescence mean lifetimes in the spectral range from 410 to 560 nm in the less susceptible varieties. Noticeable pathogen-induced modifications were also revealed by the ‘Blue-to-Far-Red Fluorescence Ratio’ and the ‘Simple Fluorescence Ratio’. Particularly in the susceptible varieties the differences became more evident in the time-course of the experiment i.e., following the pathogen development. The relevance of the blue and green fluorescence to exploit the plant-pathogen interaction was demonstrated by the multispectral fluorescence imaging system. As shown, mildewed leaves were characterized by exceptionally high blue fluorescence, contrasting the values observed in rust inoculated leaves. Further, we confirm that the intensity of green fluorescence depends on the pathogen infection and the stage of disease development; this information might allow a differentiation of both diseases. Moreover, our results demonstrate that the detection area might influence the quality of the information, although it had a minor impact only in the current study. Finally, we highlight the relevance of

Induced mutations for resistance to leaf rust in wheat

International Nuclear Information System (INIS)

Borojevic, K.

1983-01-01

Problems related to the induction of mutations for disease resistance were investigated under several aspects, using the wheat/leaf rust system. Previously selected mutant lines, tested in M 11 and M 13 , were found to differ with regard to infection type and disease severity from the original varieties. To verify the induced-mutation origin, these mutants were examined further using test crosses with carriers of known genes for leaf rust resistance and electrophoresis. A separate experiment to induce mutations for leaf rust resistance in the wheat varieties Sava, Aurora and Siete Cerros, using gamma rays, fast neutrons and EMS, yielded mutants with different disease reaction in the varieties Sava and Aurora at a frequency of about 1x10 - 3 per M 1 plant progenies. (author)

Efficacy of Combined Sous Vide-Microwave Cooking for Foodborne Pathogen Inactivation in Ready-to-Eat Chicory Stems.

Science.gov (United States)

Renna, Massimiliano; Gonnella, Maria; de Candia, Silvia; Serio, Francesco; Baruzzi, Federico

2017-07-01

There is a variety of different food processing methods, which can be used to prepare ready-to-eat foods. However, the need to preserve the freshness and nutritional qualities leads to the application of mild technologies which may be insufficient to inactivate microbial pathogens. In this work, fresh chicory stems were packed under a vacuum in films, which were transparent to microwaves. These were then exposed to microwaves for different periods of time. The application of sous vide microwave cooking (SV-MW, 900 W, 2450 MHz), controlled naturally occurring mesophilic aerobic bacteria, yeasts and molds for up to 30 d when vacuum-packed vegetables were stored at 4 °C. In addition, the process lethality of the SV-MW 90 s cooking was experimentally validated. This treatment led to 6.07 ± 0.7 and 4.92 ± 0.65 log cfu/g reduction of Escherichia coli and Listeria monocytogenes inoculated over the chicory stems (100 g), respectively. With an initial load of 9 log cfu/g for both pathogens, less than 10 cfu/g of surviving cells were found after 90 s cooking. This shows that short-time microwave cooking can be used to effectively pasteurize vacuum-packed chicory stems, achieving >5 log cfu/g reduction of E. coli and L. monocytogenes. © 2017 Institute of Food Technologists®.

Study of Rust Effect on the Corrosion Behavior of Reinforcement Steel Using Impedance Spectroscopy

Science.gov (United States)

Bensabra, Hakim; Azzouz, Noureddine

2013-12-01

Most studies on corrosion of steel reinforcement in concrete are conducted on steel samples with polished surface (free of all oxides) in order to reproduce the same experimental conditions. However, before embedding in concrete, the steel bars are often covered with natural oxides (rust), which are formed during exposure to the atmosphere. The presence of this rust may affect the electrochemical behavior of steel rebar in concrete. In order to understand the effect of rust on the corrosion behavior of reinforcement steel, potentiodynamic and electrochemical impedance spectroscopy (EIS) tests were carried out in a simulated concrete pore solution using steel samples with two different surface conditions: polished and rusted samples. The obtained results have shown that the presence of rust on the steel bar has a negative effect on its corrosion behavior, with or without the presence of chlorides. This detrimental effect can be explained by the fact that the rust provokes a decrease of the electrolyte resistance at the metal-concrete interface and reduces the repassivating ability. In addition, the rust layer acts as a barrier against the hydroxyl ion diffusion, which prevents the realkalinization phenomenon.

Orange rust in sugarcane: molecular identification in Rio de Janeiro State

Directory of Open Access Journals (Sweden)

Carla Vanessa Borges Castro

2013-09-01

Full Text Available Sugarcane (Saccharum spp. cultivation is one of the major agricultural activities in the Brazilian states. This study aimed to molecularly identify the pathogen associated with rust in sugarcane cultivars in the state of Rio de Janeiro and to suggest a control strategy. Among the 14 PCR-tested cultivars, Puccinia kuehnii infection was identified for RB947520, RB92606, RB835486, RB72454, SP89-11I5, SP83-2847, both from infected leaf sample and from urediniospores. Puccinia kuehnii was not detected by PCR for the cultivars RB955971, RB951541, RB92579, RB867515, RB855536, SP91-1049, SP80-3280, SP80-1816. This is the first molecular detection of this fungus in the state of Rio de Janeiro for six of the 14 analyzed cultivars.

Characterization of the rust formed on weathering steel exposed to Qinghai salt lake atmosphere

International Nuclear Information System (INIS)

Li, Q.X.; Wang, Z.Y.; Han, W.; Han, E.H.

2008-01-01

The product formed on weathering steel exposed to salt lake atmosphere for 12 months was investigated by X-ray diffraction (XRD), infrared transmission spectroscopy (IRS), scanning electron microscopy (SEM), electron probe micro analyzer (EPMA) and electrochemical techniques. The rust was mainly composed of β-FeOOH, Fe 8 (O,OH) 16 Cl 1.3 and a little γ-FeOOH. Amorphous δ-FeOOH was only on skyward surface. The rust layer suppressed anodic reaction and facilitated the cathodic reaction. The very small value of rust resistance R r in this work indicated that the rust had poor protective ability. Cl element was rich in the whole rust layer and played an important role in accelerating the corrosion of weathering steel in salt lake atmosphere

Relocation of a rust resistance gene R 2 and its marker-assisted gene pyramiding in confection sunflower (Helianthus annuus L.).

Science.gov (United States)

Qi, L L; Ma, G J; Long, Y M; Hulke, B S; Gong, L; Markell, S G

2015-03-01

The rust resistance gene R 2 was reassigned to linkage group 14 of the sunflower genome. DNA markers linked to R 2 were identified and used for marker-assisted gene pyramiding in a confection type genetic background. Due to the frequent evolution of new pathogen races, sunflower rust is a recurring threat to sunflower production worldwide. The inbred line Morden Cross 29 (MC29) carries the rust resistance gene, R 2 , conferring resistance to numerous races of rust fungus in the US, Canada, and Australia, and can be used as a broad-spectrum resistance resource. Based on phenotypic assessments and SSR marker analyses on the 117 F2 individuals derived from a cross of HA 89 with MC29 (USDA), R 2 was mapped to linkage group (LG) 14 of the sunflower, and not to the previously reported location on LG9. The closest SSR marker HT567 was located at 4.3 cM distal to R 2 . Furthermore, 36 selected SNP markers from LG14 were used to saturate the R 2 region. Two SNP markers, NSA_002316 and SFW01272, flanked R 2 at a genetic distance of 2.8 and 1.8 cM, respectively. Of the three closely linked markers, SFW00211 amplified an allele specific for the presence of R 2 in a marker validation set of 46 breeding lines, and SFW01272 was also shown to be diagnostic for R 2 . These newly developed markers, together with the previously identified markers linked to the gene R 13a , were used to screen 524 F2 individuals from a cross of a confection R 2 line and HA-R6 carrying R 13a . Eleven homozygous double-resistant F2 plants with the gene combination of R 2 and R 13a were obtained. This double-resistant line will be extremely useful in confection sunflower, where few rust R genes are available, risking evolution of new virulence phenotypes and further disease epidemics.

Transfer of stripe rust resistance from Aegilops variabilis to bread ...

African Journals Online (AJOL)

In terms of area, the bread wheat producing regions of China comprise the largest area in the world that is constantly threatened by stripe rust epidemics. Consequently, it is important to exploit new adultplant resistance genes in breeding. This study reports the transfer of stripe rust resistance from Aegilops variabilis to ...

Magnetic property based characterization of rust on weathering steels

International Nuclear Information System (INIS)

Mizoguchi, T.; Ishii, Y.; Okada, T.; Kimura, M.; Kihira, H.

2005-01-01

The characterization of rusts on weathering steels is important in understanding the origin of their corrosion resistance. Rust consists of several phases, e.g. α-, β- and γ-FeOOH, which are anti-ferromagnetic with different Neel temperatures. Rust on so-called advanced weathering steel containing 3 wt.% Ni [H. Kihira, A. Usami, K. Tanabe, M. Ito, G. Shigesato, Y. Tomita, T. Kusunoki, T. Tsuzuki, S. Ito, T. Murata, in: Proc. Symp. on Corrosion and Corrosion Control in Saltwater Environments, Honolulu, 1999, The Electrochemical Soc., pp. 127-136] contains in addition a ferrimagnetic spinel phase [M. Kimura, H. Kihira, Y. Ishii, T. Mizoguchi, in: Proc. 13th Asian-Pacific Corrosion Control Conference, Osaka, 2003; M. Kimura, H. Kihira, N. Ohta, M. Hashimoto, T. Senuma, Corros. Sci., this volume; M. Kimura, N. Ohta, H. Kihira, Mater. Trans. JIM, in press]. The nanostructure of real rust cannot be elucidated satisfactorily only with conventional analytical methods such as X-ray diffraction, because of the complex mixture of phases with fine and imperfect crystallites. Because of the short range of the super-exchange coupling between Fe ions in a solid, the magnetic properties can give information on local configurations even in the absence of perfect crystalline coherence. Therefore, the magnetic properties of rust samples were investigated in detail using a Superconducting Quantum Interference Device (SQUID) magnetometer and Moessbauer spectroscopy. SQUID magnetometry is effective to determine the quantity of the ferrimagnetic phase. The temperature dependence of the Moessbauer spectrum gives information about not only the fractions of the phases but also the distribution of grain volume, V, in each phase according to the super-paramagnetic relaxation effect. This approach has been applied to rust of conventional [T. Okada, Y. Ishii, T. Mizoguchi, I. Tamura, Y. Kobayashi, Y. Takagi, S. Suzuki, H. Kihira, M. Ito, A. Usami, K. Tanabe, K. Masuda, Jpn. J. Appl. Phys. 39

Bulked fusiform rust inocula and Fr gene interactions in loblolly pine

Science.gov (United States)

Fikret Isik; Henry Amerson; Saul Garcia; Ross Whetten; Steve. McKeand

2012-01-01

Fusiform rust disease in loblolly (Pinus taeda L.) and slash (Pinus elliottii Engelm. var elliottii) pine plantations in the southern United States causes multi-million dollar annual losses. The disease is endemic to the region. The fusiform rust fungus (Cronartium quercuum sp.

Influence of yellow rust infextion on 32P transport in detached barley leaves

International Nuclear Information System (INIS)

Schubert, J.

1982-01-01

Several barley cultivars (Hordeum vulgare L.) differing in their resistance to yellow rust (Puccinia striiformis West.) were tested for relationships between changes of 32 P transport in detached leaves and resistance to yellow rust disease. Investigation carried out with detached second leaves from plants infected at their first leaf revealed a matter transport in these leaves changed by the infection. Transport was also influenced by inoculation with yellow rust uredospores. In that case rust infection influenced the basipetal transport less strongly in resistent plants than in susceptible ones. Connected with the findings the influence of fungal substances on transport processes is discussed in general. (author)

Utilization of a major brown rust resistance gene in sugarcane breeding

Science.gov (United States)

Brown rust, caused by Puccinia melanocephala has had devastating effects on sugarcane (Saccharum spp.) breeding programs and on commercial production. The discovery of Bru1, a major gene conferring resistance to brown rust represented a substantial breakthrough and markers for the detection of Bru1 ...

Molecular tagging of a novel rust resistance gene R(12) in sunflower (Helianthus annuus L.).

Science.gov (United States)

Gong, L; Hulke, B S; Gulya, T J; Markell, S G; Qi, L L

2013-01-01

Sunflower production in North America has recently suffered economic losses in yield and seed quality from sunflower rust (Puccinia helianthi Schwein.) because of the increasing incidence and lack of resistance to new rust races. RHA 464, a newly released sunflower male fertility restorer line, is resistant to both of the most predominant and most virulent rust races identified in the Northern Great Plains of the USA. The gene conditioning rust resistance in RHA 464 originated from wild Helianthus annuus L., but has not been molecularly marked or determined to be independent from other rust loci. The objectives of this study are to identify molecular markers linked to the rust resistance gene and to investigate the allelism of this gene with the unmapped rust resistance genes present in HA-R6, HA-R8 and RHA 397. Virulence phenotypes of seedlings for the F(2) population and F(2:3) families suggested that a single dominant gene confers rust resistance in RHA 464, and this gene was designated as R(12). Bulked segregant analysis identified ten markers polymorphic between resistant and susceptible bulks. In subsequent genetic mapping, the ten markers covered 33.4 cM of genetic distance on linkage group 11 of sunflower. A co-dominant marker CRT275-11 is the closest marker distal to R(12) with a genetic distance of 1.0 cM, while ZVG53, a dominant marker linked in the repulsion phase, is proximal to R(12) with a genetic distance of 9.6 cM. The allelism test demonstrated that R(12) is not allelic to the rust resistance genes in HA-R6, HA-R8 and RHA 397, and it is also not linked to any previously mapped rust resistance genes. Discovery of the R(12) novel rust resistance locus in sunflower and associated markers will potentially support the molecular marker-assisted introgression and pyramiding of R(12) into sunflower breeding lines.

Resistance Potential of Bread Wheat Genotypes Against Yellow Rust Disease Under Egyptian Climate.

Science.gov (United States)

Mahmoud, Amer F; Hassan, Mohamed I; Amein, Karam A

2015-12-01

Yellow rust (stripe rust), caused by Puccinia striiformis f. sp. tritici, is one of the most destructive foliar diseases of wheat in Egypt and worldwide. In order to identify wheat genotypes resistant to yellow rust and develop molecular markers associated with the resistance, fifty F8 recombinant inbred lines (RILs) derived from a cross between resistant and susceptible bread wheat landraces were obtained. Artificial infection of Puccinia striiformis was performed under greenhouse conditions during two growing seasons and relative resistance index (RRI) was calculated. Two Egyptian bread wheat cultivars i.e. Giza-168 (resistant) and Sakha-69 (susceptible) were also evaluated. RRI values of two-year trial showed that 10 RILs responded with RRI value >6 2 rust. However, further molecular analyses would be performed to confirm markers associated with the resistance and suitable for marker-assisted selection. Resistant RILs identified in the study could be efficiently used to improve the resistance to yellow rust in wheat.

Effect of orange rust on sugarcane breeding program at canal Point

Science.gov (United States)

Orange rust of sugarcane (Saccharum spp. hybrids), caused by Puccinia kuehnii (W. Krüger) E.J. Butler, appeared in the Western Hemisphere ten years ago. Orange rust substantially reduces yields in susceptible sugarcane genotypes. Majority of the commercial cultivars were susceptible at the time of o...

Characterization and Mapping of Leaf Rust and Stripe Rust Resistance Loci in Hexaploid Wheat Lines UC1110 and PI610750 under Mexican Environments.

Science.gov (United States)

Lan, Caixia; Hale, Iago L; Herrera-Foessel, Sybil A; Basnet, Bhoja R; Randhawa, Mandeep S; Huerta-Espino, Julio; Dubcovsky, Jorge; Singh, Ravi P

2017-01-01

Growing resistant wheat varieties is a key method of minimizing the extent of yield losses caused by the globally important wheat leaf rust (LR) and stripe rust (YR) diseases. In this study, a population of 186 F 8 recombinant inbred lines (RILs) derived from a cross between a synthetic wheat derivative (PI610750) and an adapted common wheat line (cv. "UC1110") were phenotyped for LR and YR response at both seedling and adult plant stages over multiple seasons. Using a genetic linkage map consisting of single sequence repeats and diversity arrays technology markers, in combination with inclusive composite interval mapping analysis, we detected a new LR adult plant resistance (APR) locus, QLr.cim-2DS , contributed by UC1110. One co-located resistance locus to both rusts, QLr.cim-3DC/QYr.cim-3DC , and the known seedling resistance gene Lr26 were also mapped. QLr.cim-2DS and QLr.cim-3DC showed a marginally significant interaction for LR resistance in the adult plant stage. In addition, two previously reported YR APR loci, QYr.ucw-3BS and Yr48 , were found to exhibit stable performances in rust environments in both Mexico and the United States and showed a highly significant interaction in the field. Yr48 was also observed to confer intermediate seedling resistance against Mexican YR races, thus suggesting it should be re-classified as an all-stage resistance gene. We also identified 5 and 2 RILs that possessed all detected YR and LR resistance loci, respectively. With the closely linked molecular markers reported here, these RILs could be used as donors for multiple resistance loci to both rusts in wheat breeding programs.

Genetic variability among the brown rust resistant and susceptible genotypes of sugarcane by RAPD technique

Science.gov (United States)

Brown leaf rust in sugarcane is caused by Puccinia melanocephala (Syd. & P. Syd.), which is major cause of cultivar withdrawal. We attempted to analyze the RAPD diversity of two discrete phenotypic classes i.e. rust resistant (R) and rust susceptible (S) of six commercially available sugarcane elite...

White pine blister rust in northern ldaho and western Montana: alternatives for integrated management

Science.gov (United States)

Susan K. Hagle; Geral I. McDonald; Eugene A. Norby

1989-01-01

This report comprises a handbook for managing western white pine in northern ldaho and western Montana, under the threat of white pine blister rust. Various sections cover the history of the disease and efforts to combat it, the ecology of the white pine and Ribes, alternate host of the rust, and techniques for evaluating the rust hazard and attenuating it. The authors...

Physical Localization of a Locus from Agropyron cristatum Conferring Resistance to Stripe Rust in Common Wheat.

Science.gov (United States)

Zhang, Zhi; Song, Liqiang; Han, Haiming; Zhou, Shenghui; Zhang, Jinpeng; Yang, Xinming; Li, Xiuquan; Liu, Weihua; Li, Lihui

2017-11-13

Stripe rust, caused by Puccinia striiformis f. sp. tritici ( Pst ), is one of the most destructive diseases of wheat ( Triticum aestivum L.) worldwide. Agropyron cristatum (L.) Gaertn. (2 n = 28, PPPP), one of the wild relatives of wheat, exhibits resistance to stripe rust. In this study, wheat- A . cristatum 6P disomic addition line 4844-12 also exhibited resistance to stripe rust. To identify the stripe rust resistance locus from A . cristatum 6P, ten translocation lines, five deletion lines and the BC₂F₂ and BC₃F₂ populations of two wheat- A . cristatum 6P whole-arm translocation lines were tested with a mixture of two races of Pst in two sites during 2015-2016 and 2016-2017, being genotyped with genomic in situ hybridization (GISH) and molecular markers. The result indicated that the locus conferring stripe rust resistance was located on the terminal 20% of 6P short arm's length. Twenty-nine 6P-specific sequence-tagged-site (STS) markers mapped on the resistance locus have been acquired, which will be helpful for the fine mapping of the stripe rust resistance locus. The stripe rust-resistant translocation lines were found to carry some favorable agronomic traits, which could facilitate their use in wheat improvement. Collectively, the stripe rust resistance locus from A . cristatum 6P could be a novel resistance source and the screened stripe rust-resistant materials will be valuable for wheat disease breeding.

Introgression of a leaf rust resistance gene from Aegilops caudata to ...

Indian Academy of Sciences (India)

tance genes (Lr) and 48 stripe rust resistance genes (Yr) have .... Leaf rust reaction of the parents, wheat – Ae. caudata introgression lines and representative F2 plants developed from the cross: .... segregation ratio, which is otherwise a serious problem with ... Financial assistance was provided by the USDA-ARS under the.

Temporal Gene Expression Profiling of the Wheat Leaf Rust Pathosystem Using cDNA Microarray Reveals Differences in Compatible and Incompatible Defence Pathways

OpenAIRE

Fofana, Bourlaye; Banks, Travis W.; McCallum, Brent; Strelkov, Stephen E.; Cloutier, Sylvie

2007-01-01

In this study, we detail the construction of a custom cDNA spotted microarray containing 7728 wheat ESTs and the use of the array to identify host genes that are differentially expressed upon challenges with leaf rust fungal pathogens. Wheat cultivar RL6003 (Thatcher Lr1) was inoculated with Puccinia triticina virulence phenotypes BBB (incompatible) or TJB (7-2) (compatible) and sampled at four different time points (3, 6, 12, and 24 hours) after inoculation. Transcript expression levels rela...

New Spectral Index for Detecting Wheat Yellow Rust Using Sentinel-2 Multispectral Imagery

Directory of Open Access Journals (Sweden)

Qiong Zheng

2018-03-01

Full Text Available Yellow rust is one of the most destructive diseases for winter wheat and has led to a significant decrease in winter wheat quality and yield. Identifying and monitoring yellow rust is of great importance for guiding agricultural production over large areas. Compared with traditional crop disease discrimination methods, remote sensing technology has proven to be a useful tool for accomplishing such a task at large scale. This study explores the potential of the Sentinel-2 Multispectral Instrument (MSI, a newly launched satellite with refined spatial resolution and three red-edge bands, for discriminating between yellow rust infection severities (i.e., healthy, slight, and severe in winter wheat. The corresponding simulative multispectral bands for the Sentinel-2 sensor were calculated by the sensor’s relative spectral response (RSR function based on the in situ hyperspectral data acquired at the canopy level. Three Sentinel-2 spectral bands, including B4 (Red, B5 (Re1, and B7 (Re3, were found to be sensitive bands using the random forest (RF method. A new multispectral index, the Red Edge Disease Stress Index (REDSI, which consists of these sensitive bands, was proposed to detect yellow rust infection at different severity levels. The overall identification accuracy for REDSI was 84.1% and the kappa coefficient was 0.76. Moreover, REDSI performed better than other commonly used disease spectral indexes for yellow rust discrimination at the canopy scale. The optimal threshold method was adopted for mapping yellow rust infection at regional scales based on realistic Sentinel-2 multispectral image data to further assess REDSI’s ability for yellow rust detection. The overall accuracy was 85.2% and kappa coefficient was 0.67, which was found through validation against a set of field survey data. This study suggests that the Sentinel-2 MSI has the potential for yellow rust discrimination, and the newly proposed REDSI has great robustness and

New Spectral Index for Detecting Wheat Yellow Rust Using Sentinel-2 Multispectral Imagery.

Science.gov (United States)

Zheng, Qiong; Huang, Wenjiang; Cui, Ximin; Shi, Yue; Liu, Linyi

2018-03-15

Yellow rust is one of the most destructive diseases for winter wheat and has led to a significant decrease in winter wheat quality and yield. Identifying and monitoring yellow rust is of great importance for guiding agricultural production over large areas. Compared with traditional crop disease discrimination methods, remote sensing technology has proven to be a useful tool for accomplishing such a task at large scale. This study explores the potential of the Sentinel-2 Multispectral Instrument (MSI), a newly launched satellite with refined spatial resolution and three red-edge bands, for discriminating between yellow rust infection severities (i.e., healthy, slight, and severe) in winter wheat. The corresponding simulative multispectral bands for the Sentinel-2 sensor were calculated by the sensor's relative spectral response (RSR) function based on the in situ hyperspectral data acquired at the canopy level. Three Sentinel-2 spectral bands, including B4 (Red), B5 (Re1), and B7 (Re3), were found to be sensitive bands using the random forest (RF) method. A new multispectral index, the Red Edge Disease Stress Index (REDSI), which consists of these sensitive bands, was proposed to detect yellow rust infection at different severity levels. The overall identification accuracy for REDSI was 84.1% and the kappa coefficient was 0.76. Moreover, REDSI performed better than other commonly used disease spectral indexes for yellow rust discrimination at the canopy scale. The optimal threshold method was adopted for mapping yellow rust infection at regional scales based on realistic Sentinel-2 multispectral image data to further assess REDSI's ability for yellow rust detection. The overall accuracy was 85.2% and kappa coefficient was 0.67, which was found through validation against a set of field survey data. This study suggests that the Sentinel-2 MSI has the potential for yellow rust discrimination, and the newly proposed REDSI has great robustness and generalized ability

Mechanical properties of the rust layer induced by impressed current method in reinforced mortar

International Nuclear Information System (INIS)

Care, S.; Nguyen, Q.T.; L'Hostis, V.; Berthaud, Y.

2008-01-01

This paper describes the mechanical effects of rust layer formed in reinforced mortar through accelerated tests of corrosion. The morphological and physico-chemical properties (composition, structures) of the corrosion system were characterized at different stages by using optical microscope and scanning electron microscope coupled with energy dispersive spectroscopy. The corrosion pattern was mainly characterized by a rust layer confined at the interface between the steel and the mortar. Expansion coefficient of rust products was determined from the rust thickness and the Faraday's law. Furthermore, in order to understand the mechanical effects of corrosion on the damage of mortar, displacement field measurements were obtained by using digital image correlation. An analytical model (hollow cylinder subjected to inner and outer pressures) was used with a set of experimental data to deduce the time of cracking and the order of magnitude of the mechanical properties of the rust layer

Influence of yellow rust infection on /sup 32/P transport in detached barley leaves

Energy Technology Data Exchange (ETDEWEB)

Schubert, J. (Akademie der Landwirtschaftswissenschaften der DDR, Aschersleben. Inst. fuer Phytopathologie)

1982-01-01

Several barley cultivars (Hordeum vulgare L.) differing in their resistance to yellow rust (Puccinia striiformis West.) were tested for relationships between changes of /sup 32/P transport in detached leaves and resistance to yellow rust disease. Investigation carried out with detached second leaves from plants infected at their first leaf revealed a matter transport in these leaves changed by the infection. Transport was also influenced by inoculation with yellow rust uredospores. In that case rust infection influenced the basipetal transport less strongly in resistent plants than in susceptible ones. Connected with the findings the influence of fungal substances on transport processes is discussed in general.

Resistance to white pine blister rust in Pinus flexilis and P

Science.gov (United States)

Anna W. Schoettle; Richard A. Sniezko; Angelia Kegley; Jerry Hill; Kelly S. Burns

2010-01-01

The non-native fungus Cronartium ribicola, that causes white pine blister rust (WPBR), is impacting or threatening limber pine, Pinus flexilis, and Rocky Mountain bristlecone pine, Pinus aristata. In the Southern Rockies, where the rust invasion is still expanding, we have the opportunity to be proactive and prepare the landscape for invasion. Genetic...

MICROCOSM STUDY OF DEGRADATION OF CHLORINATED SOLVENTS ON SYNTHETIC GREEN RUST MINERALS

Science.gov (United States)

Green rust minerals contain ferrous ion in their structure that can potentially serve as a chemical reductant for degradation of chlorinated solvents. Green rusts are found in zerovalent iron based permeable reactive barriers and in certain soil and sediments. Some previous labor...

Effects of rust in the crack face on crack detection based on Sonic-IR method

International Nuclear Information System (INIS)

Harai, Y.; Izumi, Y.; Tanabe, H.; Takamatsu, T.; Sakagami, T.

2015-01-01

Sonic-IR, which is based on the thermographic detection of the temperature rise due to frictional heating at the defect faces under ultrasonic excitation, has an advantage in the detection of closed and small defects. However, this method has a lot of nuclear factors relating to heat generation. In this study, effects of rust in the crack faces on the crack detection based on the sonic-IR method is experimentally investigated by using crack specimens. The heat generation by ultrasonic excitation was observed regularly during rust accelerated test using original device. The distribution of temperature change around the crack was changed with the progress of rust. This change in heat generation, it believed to be due to change in the contact state of the crack surface due to rust. As a result, it was found that heat generation by ultrasonic excitation is affected by rust in the crack faces. And it was also found that crack detection can be conducted by sonic-IR even if rust was generated in the crack faces. (author)

Quantitative characterization of the atomic-scale structure of oxyhydroxides in rusts formed on steel surfaces

International Nuclear Information System (INIS)

Saito, M.; Suzuki, S.; Kimura, M.; Suzuki, T.; Kihira, H.; Waseda, Y.

2005-01-01

Quantitative X-ray structural analysis coupled with anomalous X-ray scattering has been used for characterizing the atomic-scale structure of rust formed on steel surfaces. Samples were prepared from rust layers formed on the surfaces of two commercial steels. X-ray scattered intensity profiles of the two samples showed that the rusts consisted mainly of two types of ferric oxyhydroxide, α-FeOOH and γ-FeOOH. The amounts of these rust components and the realistic atomic arrangements in the components were estimated by fitting both the ordinary and the environmental interference functions with a model structure calculated using the reverse Monte Carlo simulation technique. The two rust components were found to be the network structure formed by FeO 6 octahedral units, the network structure itself deviating from the ideal case. The present results also suggest that the structural analysis method using anomalous X-ray scattering and the reverse Monte Carlo technique is very successful in determining the atomic-scale structure of rusts formed on the steel surfaces

Induced mutations for rust resistance in bread wheat

International Nuclear Information System (INIS)

Sawhney, R.N.

1989-01-01

Full text: Seeds of variety ''Lalbahadur'' were treated with 0.04% NMH. M 2 plants were inoculated with a mixture of pathotypes of each of the 3 Puccinia species (P. graminis, P. recondita, P. striiformis). Plants with simultaneous resistance to all 3 rusts were selected. Repeated testing in subsequent generations confirmed the resistance. The mutant lines are morphologically similar to the parent cultivar and therefore could be used as components of a multiline variety. Comparison of variety pattern against the Indian pathotypes of rusts suggests that the mutant genes are different from the ones known already in bread wheat. (author)

Potential impact of the global climate changes on the spatial distribution of areas of risk for the occurrence of eucalyptus rust in Brazil

Directory of Open Access Journals (Sweden)

Willian Bucker Moraes

2014-06-01

Full Text Available Rust, caused by Puccinia psidii, is one of the most important diseases affecting eucalyptus in Brazil. This pathogen causes disease in mini-clonal garden and in young plants in the field, especially in leaves and juvenile shoots. Favorable climate conditions for infection by this pathogen in eucalyptus include temperature between 18 and 25 ºC, together with at least 6-hour leaf wetness periods, for 5 to 7 consecutive days. Considering the interaction between the environment and the pathogen, this study aimed to evaluate the potential impact of global climate changes on the spatial distribution of areas of risk for the occurrence of eucalyptus rust in Brazil. Thus, monthly maps of the areas of risk for the occurrence of this disease were elaborated, considering the current climate conditions, based on a historic series between 1961 and 1990, and the future scenarios A2 and B2, predicted by IPCC. The climate conditions were classified into three categories, according to the potential risk for the disease occurrence, considering temperature (T and air relative humidity (RH: i high risk (18 90%; ii medium risk (18 25 ºC and RH > 90%; and iii low risk (T 25 ºC and RH < 90%. Data about the future climate scenarios were supplied by GCM Change Fields. In this study, the simulation model Hadley Centers for Climate Prediction and Research (HadCm3 was adopted, using the software Idrisi 32. The obtained results led to the conclusion that there will be a reduction in the area favorable to eucalyptus rust occurrence, and such a reduction will be gradual for the decades of 2020, 2050 and 2080 but more marked in scenario A2 than in B2. However, it is important to point out that extensive areas will still be favorable to the disease development, especially in the coldest months of the year, i.e., June and July. Therefore, the zoning of areas and periods of higher occurrence risk, considering the global climate changes, becomes important knowledge for the

Strategies for managing whitebark pine in the presence of white pine blister rust [Chapter 17

Science.gov (United States)

Raymond J. Hoff; Dennis E. Ferguson; Geral I. McDonald; Robert E. Keane

2001-01-01

Whitebark pine (Pinus albicaulis) is one of many North American white pine species (Pinus subgenus Strobus) susceptible to the fungal disease white pine blister rust (Cronartium ribicola). Blister rust has caused severe mortality (often reaching nearly 100 percent) in many stands of white bark pine north of 45° latitude in western North America. The rust is slowly...

Low average blister-rust infection rates may mean high control costs

Science.gov (United States)

Robert Marty

1965-01-01

The Northeastern Forest Experiment Station, in cooperation with Federal and State forest-pest-control agencies, undertook a survey of blister-rust infection rates in the white pine region of the East during 1962 and 1963. Those engaged in blister-rust-control activities will not be surprised at the survey's results. We found that infection rates were significantly...

Determining yield loss caused by brown rust in production fields of sugarcane

Science.gov (United States)

Infections of Puccinia melanocephala, the causal agent of brown rust, appear on Louisiana sugarcane in the spring. Disease expression is usually limited to 2 to 3 months until temperatures exceed those favorable for spore production. The affected sugarcane is harvested 4 to 6 months after rust sympt...

Screening for Sugarcane Brown Rust in the First Clonal Stage of the Canal Point Sugarcane Breeding Program

Directory of Open Access Journals (Sweden)

Duli Zhao

2015-07-01

Full Text Available Sugarcane (Saccharum spp. brown rust (caused by Puccinia melanocephala Syd. & P. Syd. was first reported in the United States in 1978 and is still one of the great challenges for sugarcane production. A better understanding of sugarcane genotypic variation in response to brown rust will help optimize breeding and selection strategies for disease resistance. Brown rust ratings were scaled from non-infection (0 to severe infection (4 with intervals of 0.5 and routinely recorded for genotypes in the first clonal selection stage of the Canal Point sugarcane breeding program in Florida. Data were collected from 14,272 and 12,661 genotypes and replicated check cultivars in 2012 and 2013, respectively. Mean rust rating, % infection, and severity in each family and progeny of female parent were determined, and their coefficients of variation (CV within and among families (females were estimated. Considerable variation exists in rust ratings among families or females. The families and female parents with high susceptibility or resistance to brown rust were identified and ranked. The findings of this study can help scientists to evaluate sugarcane crosses and parents for brown rust disease, to use desirable parents for crossing, and to improve genetic resistance to brown rust in breeding programs.

Detection of Puccinia kuehnii Causing Sugarcane Orange Rust with a Loop-Mediated Isothermal Amplification-Based Assay.

Science.gov (United States)

Chandra, Amaresh; Keizerweerd, Amber T; Grisham, Michael P

2016-03-01

Puccinia kuehnii is a fungal pathogen that causes orange rust in sugarcane, which is now prevalent in many countries. At the early stage of disease, it is almost indistinguishable from brown rust, which is caused by Puccinia melanocephala. Although several PCR assays are available to detect these diseases, the loop-mediated isothermal amplification (LAMP)-based assay has been reported to be more economical and easier to perform. Under isothermal conditions, DNA is amplified with high specificity and rapidity. Moreover, visual judgment of color change without further post-amplification processing makes the method convenient. The present study was undertaken to detect P. kuehnii genomic DNA using four primers corresponding to a unique DNA sequence of P. kuehnii. The LAMP assay was found to be optimal when 8 mM MgSO4 was used and the reaction was incubated at 63 °C for 90 min. Positive samples showed a color change from orange to green upon SYBR Green I dye addition. Specificity of the LAMP test was checked with DNA of P. melanocephala, which showed no reaction. Sensitivity of the LAMP method was observed to be the same as real-time PCR at 0.1 ng, thus providing a rapid and more affordable option for early disease detection.

A perspective of leaf rust race fhprn and its impact on leaf rust resistance in pakistani wheat varieties

International Nuclear Information System (INIS)

Sohail, Y.

2015-01-01

Leaf rust infected leaves of a widely growing variety Seher-06 were collected in wheat season of 2011-12. The leaf rust isolates were assessed on Thatcher derived Lr isogenic lines and a race FHPRN was identified. Seventy six wheat varieties/lines besides Lr isogenic lines were screened against this race for seedling in glass house and for adult plant resistance at Bahawalpur and Faisalabad during 2012-13. Lr1, Lr2a, Lr9, Lr19, Lr24, Lr10+27+31 (Gatcher) and Lr28 were found completely resistant at both stages against FHPRN. Molecular screening of the wheat varieties/lines indicated the presence of leaf rust resistance genes Lr9 (0%), Lr13 (43%), Lr19 (1%), Lr20 (0%), Lr24 (4%), Lr26 (23%), Lr28 (0%), Lr34 (38%), Lr37 (1%) and Lr47 (1%) in them. Field data suggested that As-02 (Lr10+26+34), Bhakar-02 (Lr13) and Shafaq-06 (Lr10+13+27) were resistant; Pasban-90 (Lr10+13+26+27), Chenab-2000 (Lr10+13+26+27+31+34), Fbd-08 (Lr10), Millat-11 (unknown) and Punjab-11 (unknown) were found moderately resistant; Blue silver (Lr13+14a), Pak-81 (Lr10+23+26+31), Bahawalpur-97 (Lr13+26) and Lasani-08 (Lr13+27+31) were susceptible while Sh-88 (unknown), Auqab-2000 (Lr10+23+26+27+31), Iqbal-2000 (Lr3+10+13+26+27+31), Bahawalpur-2000 (Lr34) and Seher-06 (Lr10+27+31) were found highly susceptible against FHPRN. Present and previous studies revealed the presence of Lr3, 10, 13, 14a, 23, 26, 27, 31 and 34 in the Pakistani wheat varieties yet lacking Lr9, 19, 24 and 28. Therefore, the latter genes and their effective combinations should be incorporated in Pakistani varieties to combat leaf rust effectively. (author)

A study of the evolution of rust on Mo–Cu-bearing fire-resistant steel submitted to simulated atmospheric corrosion

International Nuclear Information System (INIS)

Hao Long; Zhang Sixun; Dong Junhua; Ke Wei

2012-01-01

Highlights: ► The rusting evolution of a Mo–Cu-bearing fire-resistant steel in a simulated industrial atmosphere was investigated. ► The rusting evolution of the steel is related to the rust composition, structure, and electrochemical characteristics. ► Increased content of α-FeOOH and decreased γ-FeOOH and Fe 3 O 4 indicate the enhanced resistance of the rust. ► Mo and Cu are involved in the formation of molybdate and Cu(I)-bearing compounds in the rust. - Abstract: The corrosion evolution of a Mo–Cu-bearing fire-resistant steel in a simulated industrial atmosphere was investigated by corrosion weight gain, XRD, EPMA, XPS, and polarization curves. The results indicate that the corrosion kinetics is closely related to the rust composition and electrochemical properties. As the corrosion proceeds, the relative content of γ-FeOOH and Fe 3 O 4 decreases and α-FeOOH increases, and the rust layer becomes compact and adherent to steel substrate. Molybdenum and copper enrich in the inner rust layer, especially at the bottom of the corrosion nest, forming non-soluble molybdate and Cu(I)-bearing compounds responsible for enhanced corrosion resistance of the rust layer.

Screening and incorporation of rust resistance from Allium cepa into bunching onion (Allium fistulosum) via alien chromosome addition.

Science.gov (United States)

Wako, Tadayuki; Yamashita, Ken-ichiro; Tsukazaki, Hikaru; Ohara, Takayoshi; Kojima, Akio; Yaguchi, Shigenori; Shimazaki, Satoshi; Midorikawa, Naoko; Sakai, Takako; Yamauchi, Naoki; Shigyo, Masayoshi

2015-04-01

Bunching onion (Allium fistulosum L.; 2n = 16), bulb onion (Allium cepa L. Common onion group), and shallot (Allium cepa L. Aggregatum group) cultivars were inoculated with rust fungus, Puccinia allii, isolated from bunching onion. Bulb onions and shallots are highly resistant to rust, suggesting they would serve as useful resources for breeding rust resistant bunching onions. To identify the A. cepa chromosome(s) related to rust resistance, a complete set of eight A. fistulosum - shallot monosomic alien addition lines (MAALs) were inoculated with P. allii. At the seedling stage, FF+1A showed a high level of resistance in controlled-environment experiments, suggesting that the genes related to rust resistance could be located on shallot chromosome 1A. While MAAL, multi-chromosome addition line, and hypoallotriploid adult plants did not exhibit strong resistance to rust. In contrast to the high resistance of shallot, the addition line FF+1A+5A showed reproducibly high levels of rust resistance.

A comparative study of nitrite reduction by synthetic and biogenic Fe(II-III) hydroxysalts green rusts: Evidence for hydroxyl-nitrite green rust formation as an intermediate reaction product.

Science.gov (United States)

Ona-Nguema, G.; Guerbois, D.; Morin, G.; Zhang, Y.; Noel, V.; Brest, J.

2013-12-01

The occurrence of high nitrite concentrations as a result of anthropogenic activities is an important water quality concern as it is highly toxic to human and fauna, and it is used as a nitrogen source for the assimilation process. The toxicity of nitrite is related to its transformation into carcinogenic N-nitroso compounds, which are suspected to be responsible for some gastric cancers, and to its ability to convert the hemoglobin to methaemoglobin what is then unable to fix oxygen and to transport it to the tissues, involving hypoxia and the blue-baby syndrome [1]. To reduce the adverse effect of nitrite on human health and on macroalgal blooms, any process enhancing the transformation of nitrite ions to nitrogen gas is of interest for the remediation of natural environments. To achieve this purpose the use of processes involving Fe(II)-containing minerals could be considered as one of the best options. Green-rusts are mixed Fe(II-III) layered double hydroxides commonly found in anoxic zones of natural environments such as sediments and hydromorphic soils. In such anoxic environments, green rust minerals play an important role in the biogeochemical redox cycling of iron and nitrogen, and can affect the speciation and mobility of many organic and inorganic contaminants. The present study investigates the reduction of nitrite by two synthetic and two biogenic green rusts. On the one hand, Fe(II-III) hydroxychloride and Fe(II-III) hydroxycarbonate green rusts were used as synthetic interlayer forms of GR, which are referred to as ';syn-GR(CO3)' and ';syn-GR(Cl)', respectively. On the other hand, the study was performed with biogenic Fe(II-III) hydroxycarbonate green rusts obtained from the bioreduction of two ferric precursors, either Fe(III)-oxyhydroxycarbonate or lepidocrocite; these biogenic green rusts are referred to as ';bio-GR(CO3)F' and ';bio-GR(CO3)L', respectively. For synthetic green rusts, results showed that the oxidation of both syn-GR(CO3) and syn

Partial resistance to stripe rust and its effect on sustainability of wheat yield

International Nuclear Information System (INIS)

Qamar, M.; Din, R.U.; Gardazi, D.A.

2014-01-01

Stripe rust (Puccinia striiformis Westend. f. sp. tritici) poses a serious threat to wheat production in cooler areas of Pakistan. The 70% area of wheat in Pakistan is prone to stripe rust disease. It can cause 10-17% yield losses if susceptible cultivars are planted under favorable conditions. Level of partial plant resistance in bread wheat and its impact on sustainable wheat production was studied at the National Agricultural Research Centre, Islamabad under natural conditions in the field. Eleven Pakistani commercial wheat cultivars/advance lines including check (Inqalab 91) were assessed for the level of partial resistance against stripe rust using Area Under the Disease Progress Curve (AUDPC), disease severity (DS) and epidemic growth rate in comparison with wheat cultivar, Inqalab 91. During 2007 cropping season, natural epidemic was developed and relative AUDPC was recorded from 0 to 100% whereas the 2008 cropping season was dry and no stripe rust appeared. Two advanced lines (NR 268 and NR 285) showed the infection type (IT) less than 7 (incompatible reaction) to the mixture of prevailing stripe rust inoculums. Very low level of DS and AUDPC were recorded in the remaining cultivars/lines indicating a high level of partial resistance to stripe rust compared to the susceptible check cultivar, Inqalab 91. Among eight cultivars/lines that showed compatible type of reaction (IT greater then equal to 7), one was resistant (relative AUDPC = 20% of Inqalab 91) and six showed very high resistance levels (relative AUDPC greater then equal to 5%). Maximum level of resistance (relative AUDPC = 0.1%) was observed in advanced line, NR 271. The wheat cultivars/lines that showed a slow disease development (low DS and AUDPC), could be considered as -1 partially resistant for stripe rust infection. The yield (2178 kg ha) of susceptible check cultivar Inqalab-91 during 2007 was reduced to 45% as -1 compared to its yield (3945 kg ha) in epidemic free year (2008). Thus the use

Long-term changes in fusiform rust incidence in the southeastern United States

Science.gov (United States)

KaDonna C. Randolph; Ellis B. Cowling; Dale A. Starkey

2015-01-01

Fusiform rust is the most devastating disease of slash pine (Pinus elliottii) and loblolly pine (Pinus taeda) in the southeastern United States. Since the 1970s, the USDA Forest Service Forest Inventory and Analysis (FIA) Program has assessed fusiform rust incidence on its network of ground plots in 13 states across the...

[Prediction model of meteorological grade of wheat stripe rust in winter-reproductive area, Sichuan Basin, China].

Science.gov (United States)

Guo, Xiang; Wang, Ming Tian; Zhang, Guo Zhi

2017-12-01

The winter reproductive areas of Puccinia striiformis var. striiformis in Sichuan Basin are often the places mostly affected by wheat stripe rust. With data on the meteorological condition and stripe rust situation at typical stations in the winter reproductive area in Sichuan Basin from 1999 to 2016, this paper classified the meteorological conditions inducing wheat stripe rust into 5 grades, based on the incidence area ratio of the disease. The meteorological factors which were biologically related to wheat stripe rust were determined through multiple analytical methods, and a meteorological grade model for forecasting wheat stripe rust was created. The result showed that wheat stripe rust in Sichuan Basin was significantly correlated with many meteorological factors, such as the ave-rage (maximum and minimum) temperature, precipitation and its anomaly percentage, relative humidity and its anomaly percentage, average wind speed and sunshine duration. Among these, the average temperature and the anomaly percentage of relative humidity were the determining factors. According to a historical retrospective test, the accuracy of the forecast based on the model was 64% for samples in the county-level test, and 89% for samples in the municipal-level test. In a meteorological grade forecast of wheat stripe rust in the winter reproductive areas in Sichuan Basin in 2017, the prediction was accurate for 62.8% of the samples, with 27.9% error by one grade and only 9.3% error by two or more grades. As a result, the model could deliver satisfactory forecast results, and predicate future wheat stripe rust from a meteorological point of view.

Remapping of the stripe rust resistance gene Yr10 in common wheat.

Science.gov (United States)

Yuan, Cuiling; Wu, Jingzheng; Yan, Baiqiang; Hao, Qunqun; Zhang, Chaozhong; Lyu, Bo; Ni, Fei; Caplan, Allan; Wu, Jiajie; Fu, Daolin

2018-02-23

Yr10 is an important gene to control wheat stripe rust, and the search for Yr10 needs to be continued. Wheat stripe rust or yellow rust is a devastating fungal disease caused by Puccinia striiformis f. sp. tritici (Pst). Host disease resistance offers a primary source for controlling wheat stripe rust. The stripe rust resistance gene Yr10 confers the race-specific resistance to most tested Pst races in China including CYR29. Early studies proposed that Yr10 was a nucleotide-binding site, leucine-rich repeat gene archived as GenBank accession AF149112 (hereafter designated the Yr10 candidate gene or Yr10 CG ). In this study, we revealed that 15 Chinese wheat cultivars positive for Yr10 CG are susceptible to CYR29. We then expressed the Yr10 CG cDNA in the common wheat 'Bobwhite'. The Yr10 CG -cDNA positive transgenic plants were also susceptible to CYR29. Thus, it is highly unlikely that Yr10 CG corresponds to the Yr10 resistance gene. Using the Yr10 donor 'Moro' and the Pst-susceptible wheat 'Huixianhong', we generated two F 3 populations that displayed a single Mendelian segregation on the Yr10 gene, and used them to remap the Yr10 gene. Six markers were placed in the Yr10 region, with the Yr10 CG gene now mapping about 1.2-cM proximal to the Yr10 locus and the Xsdauw79 marker is completely linked to the Yr10 locus. Apparently, the Yr10 gene has not yet been identified. Fine mapping and positional cloning of Yr10 is important for gene pyramiding for stripe rust resistance in wheat.

Control of Fe(O,OH)6 nano-network structures of rust for high atmospheric-corrosion resistance

International Nuclear Information System (INIS)

Kimura, Masao; Kihira, Hiroshi; Ohta, Noriaki; Hashimoto, Misao; Senuma, Takehide

2005-01-01

A new-type of weathering steel containing 3.0 mass% Ni and 0.4 mass% Cu ('advanced weathering steel') exhibits good atmospheric-corrosion resistance in an atmosphere containing relatively high air-born salinity. Here, we show that the high performance was successfully achieved by controlling Fe(O,OH) 6 nano-network structures of rust formed on their surfaces. A novel technique using synchrotron radiation has been developed for the in situ observation of rust-formation during wet-dry cycles. It has been revealed that the evolution of Fe(O,OH) 6 nano-network structures of rust formed on the advanced weathering steel was more unique than those of conventional weathering steel and mild steel. At an early stage of reaction, Fe 2 NiO 4 and CuO phases precipitate, which provide sites for the nucleation of the Fe(O,OH) 6 nano-network resulting in the formation of rust composed of fine and dense-packed grains. The existence of Fe 2 NiO 4 in the nano-network changes the ion-exchanging properties of rust from anion to cation selective. Then, the rust on the advanced weathering steel 'breathes out' chloride ions from the rust/steel interface, and protects steel for more than a century by reducing the life cycle maintenance cost in an environment-friendly manner

Mapping genes for resistance to stripe rust in spring wheat landrace PI 480035

Science.gov (United States)

Stripe rust caused by Puccinia striiformis Westend. f. sp. tritici Erikks. is an economically important disease of wheat (Triticum aestivum L.). Hexaploid spring wheat landrace PI 480035 was highly resistant to stripe rust in the field in Washington during 2011 and 2012. The objective of this resear...

Genome-Wide Association Mapping of Leaf Rust Response in a Durum Wheat Worldwide Germplasm Collection.

Science.gov (United States)

Aoun, Meriem; Breiland, Matthew; Kathryn Turner, M; Loladze, Alexander; Chao, Shiaoman; Xu, Steven S; Ammar, Karim; Anderson, James A; Kolmer, James A; Acevedo, Maricelis

2016-11-01

Leaf rust (caused by Erikss. []) is increasingly impacting durum wheat ( L. var. ) production with the recent appearance of races with virulence to widely grown cultivars in many durum producing areas worldwide. A highly virulent race on durum wheat was recently detected in Kansas. This race may spread to the northern Great Plains, where most of the US durum wheat is produced. The objective of this study was to identify sources of resistance to several races from the United States and Mexico at seedling stage in the greenhouse and at adult stage in field experiments. Genome-wide association study (GWAS) was used to identify single-nucleotide polymorphism (SNP) markers associated with leaf rust response in a worldwide durum wheat collection of 496 accessions. Thirteen accessions were resistant across all experiments. Association mapping revealed 88 significant SNPs associated with leaf rust response. Of these, 33 SNPs were located on chromosomes 2A and 2B, and 55 SNPs were distributed across all other chromosomes except for 1B and 7B. Twenty markers were associated with leaf rust response at seedling stage, while 68 markers were associated with leaf rust response at adult plant stage. The current study identified a total of 14 previously uncharacterized loci associated with leaf rust response in durum wheat. The discovery of these loci through association mapping (AM) is a significant step in identifying useful sources of resistance that can be used to broaden the relatively narrow leaf rust resistance spectrum in durum wheat germplasm. Copyright © 2016 Crop Science Society of America.

Abnormal germling development by brown rust and powdery mildew on cer barley mutants

NARCIS (Netherlands)

Rubiales, D.; Ramirez, M.C.; Carver, T.L.W.; Niks, R.E.

2001-01-01

The barley leaf rust fungus forms appressoria over host leaf stomata and penetrates via the stomatal pore. High levels of avoidance to leaf rust fungi have been described in some wild accessions of Hordeum species where a prominent wax layer on the stomata inhibits triggering of fungal appressorium

Grain yield losses in yellow-rusted durum wheat estimated using digital and conventional parameters under field conditions

Directory of Open Access Journals (Sweden)

Omar Vergara-Diaz

2015-06-01

Full Text Available The biotrophic fungus Puccinia striiformis f. sp. tritici is the causal agent of the yellow rust in wheat. Between the years 2010–2013 a new strain of this pathogen (Warrior/Ambition, against which the present cultivated wheat varieties have no resistance, appeared and spread rapidly. It threatens cereal production in most of Europe. The search for sources of resistance to this strain is proposed as the most efficient and safe solution to ensure high grain production. This will be helped by the development of high performance and low cost techniques for field phenotyping. In this study we analyzed vegetation indices in the Red, Green, Blue (RGB images of crop canopies under field conditions. We evaluated their accuracy in predicting grain yield and assessing disease severity in comparison to other field measurements including the Normalized Difference Vegetation Index (NDVI, leaf chlorophyll content, stomatal conductance, and canopy temperature. We also discuss yield components and agronomic parameters in relation to grain yield and disease severity. RGB-based indices proved to be accurate predictors of grain yield and grain yield losses associated with yellow rust (R2 = 0.581 and R2 = 0.536, respectively, far surpassing the predictive ability of NDVI (R2 = 0.118 and R2 = 0.128, respectively. In comparison to potential yield, we found the presence of disease to be correlated with reductions in the number of grains per spike, grains per square meter, kernel weight and harvest index. Grain yield losses in the presence of yellow rust were also greater in later heading varieties. The combination of RGB-based indices and days to heading together explained 70.9% of the variability in grain yield and 62.7% of the yield losses.

Pathogenic characterization of lasiodplodia causing stem end rot of mango and its control using botanicals

International Nuclear Information System (INIS)

Ullah, S. F.; Hussain, Y.; Iram, S.

2017-01-01

Two widely cultivated mango fruit varieties White chounsa and Sindhri were collected from two major mango growing areas of Punjab and Sindh Provinces of Pakistan. This study was focused on pathological characterization of predominant postharvest diseases such as stem end rot of mango (Mangifera indica) caused by Lasiodiplodia theobromae, and evaluation of bio-control activity by different plant extracts. L. theobromae aggressiveness of isolates was tested by artificial inoculations under controlled conditions, all isolates proved pathogenic in varying degree of aggressiveness on (Sindhri and White chounsa) with reference to control. Calculated standard error mean varied in lesion area produced by pathogens 6-63cm/sup 2/ (Sindhri) and 60-170 cm/sup 2/ (White chounsa). Re-isolation of respective fungi verified the Koch's postulates. Plant extract of Datura stramonium, Aloe-vera, Eucalyptus camaldulensis, were used to control the radial growth of L. theobromae. Comparative analysis showed D. Stramonium and E. camaldulensis extracts most efficiently reduced the growth of Lasiodiplodia isolates, in comparison to Aloe-vera extract, restrict the 15-20% growth. All pathological results and treatments were significant at p<0.05 through ANOVA. This study emphasizes the behavior of pathogens which could be helpful in mango breeding to introduce resistance toward Lasiodiplodia and referred plants provide the best alternative of chemical fungicides. (author)

Chemical reduction of rust on 2 1/4 Cr-1 Mo steel surface in sodium

International Nuclear Information System (INIS)

Yokota, N.; Shimoyashiki, S.

1986-01-01

Low-alloy Fe-2 1/4 Cr-1 Mo ferritic steel has been favored for the tube material of steam generators in fast breeder reactors (FBRs). However, this material rusts easily due to moisture condensation on its surface when left in air. Therefore, measures to prevent tube materials from rusting have been taken during manufacturing of the steam generators. When rust is present on tube surfaces, its oxygen and iron dissolve into liquid sodium. When the concentration of these impurities in the sodium increases rapidly, the cold traps can become choked locally and lose their removal ability. This work has been done, therefore, to clarify reduction processes of rust in sodium and to select optimum operating temperatures of steam generators in the initial operation

Environment-Friendly Control of Pear Scab and Rust Using Lime Sulfur

Directory of Open Access Journals (Sweden)

Ju Hoon Cha

2018-03-01

Full Text Available Pear scab and rust are the major diseases causing severe epidemics in organic cultivation of pear trees. Incidences of pear scab and rust were compared in organically managed plots and conventionally managed plots to obtain optimum application schedule of environment-friendly control agents in organically managed plots. Organically cultural practice with 10 time-applications of lime sulfur and Bordeaux mixture showed higher than 40% of control efficacies of pear scab and rust compared to conventionally cultural practice. Organically cultural practice with 8 time-applications of lime sulfur considering weather condition showed higher than 30% of control efficacies of pear scab compared to conventionally cultural practice. The results suggest that proper application of environment-friendly control agents such as lime sulfur considering weather condition will enable effective control of the major diseases for organic cultivation of pear.

Rust formed on cannons of XVIII century under two environment conditions

International Nuclear Information System (INIS)

Cindra Fonseca, M.P.; Bastos, I.N.; Caytuero, A.; Baggio Saitovitch, E.M.

2007-01-01

The corrosion products of two ancient cannons exposed to atmospheric corrosion were analysed by X-ray powder diffraction, transmission Moessbauer spectroscopy and scanning electron microscopy (SEM). After almost three centuries exposed in marine environment one of them was moved to a rural region and was maintained in this environment for approximately 30 years. The inland region has an altitude of 1000 m above sea level and consequently low aggressiveness. The studied rusts were obtained from external and internal surfaces of the cannon barrels. This investigation, using three different techniques, was done to check if the relatively short time (ca. 30 years) in rural area was sufficient to change the characteristics of the thick rust formed during long time exposure (ca. 300 years) in marine atmosphere. The time-environment effects change the physical nature of rust, mainly observed by Moessbauer spectroscopy results

Zoete rust : Een muzikale soap-detective

NARCIS (Netherlands)

Maas, P.

1989-01-01

De komedie' Zoete Rust' werd geschreven in opdracht van Theater de Tobbe in Voorburg . Naast de circa 120 professionele voorstellingen die elk seizoen in dit theater plaats vinden, organiseert De Tobbe een maal per laar een eigen theaterproduktie, die wordt gespeeld door het Tobbe-toneel, een ad-hoc

Inheritance of resistance to Ug99 stem rust pathogen in selected ...

African Journals Online (AJOL)

13 × 08-UT-86 (χ2 0.05 = 0.480, P ≥ 0.488), HKBL-1385-13 × 09-N2-19 (χ2 0.05 = 0.641, P ≥ 0.424), ND2649 × 09-AB-78 (χ2 0.05 = 1.05, P ≥ 0.309) and ND25882 × 09-AB-78 (χ2 0.05 = 3.599, P ≥ 0.058) exhibited Mendelian segregation ...

Genetics and mapping of a new leaf rust resistance gene in Triticum ...

Indian Academy of Sciences (India)

Genetic analysis in F1, F2 and F2.3 families at the seedling stage revealed that leaf rust resistance in Selection G12 is conditioned by a single incompletely dominant gene. The leaf rust resistance gene was mapped to chromosome 3BL with SSR markers Xgwm114 and Xgwm547 flanking the gene at a distance of 28.3 cM ...

Green rusts synthesis by coprecipitation of Fe II-Fe III ions and mass-balance diagram

Science.gov (United States)

Ruby, Christian; Aïssa, Rabha; Géhin, Antoine; Cortot, Jérôme; Abdelmoula, Mustapha; Génin, Jean-Marie

2006-06-01

A basic solution is progressively added to various mixed Fe II-Fe III solutions. The nature and the relative quantities of the compounds that form can be visualised in a mass-balance diagram. The formation of hydroxysulphate green rust {GR( SO42-)} is preceded by the precipitation of a sulphated ferric basic salt that transforms in a badly ordered ferric oxyhydroxide. Then octahedrally coordinated Fe II species and SO42- anions are adsorbed on the FeOOH surface and GR( SO42-) is formed at the solid/solution interface. By using the same method of preparation, other types of green rust were synthesised, e.g. hydroxycarbonate green rust {GR( CO32-)}. Like other layered double hydroxides, green rusts obey the general chemical formula [ṡ[ṡmHO]x+ with x⩽1/3. Al-substituted hydroxysulphate green rust consists of small hexagonal crystals with a lateral size ˜50 nm, which is significantly smaller than the size of the GR( SO42-) crystals (˜500 nm). To cite this article: C. Ruby et al., C. R. Geoscience 338 (2006).

Characterization of Novel Gene Yr79 and Four Additional Quantitative Trait Loci for All-Stage and High-Temperature Adult-Plant Resistance to Stripe Rust in Spring Wheat PI 182103.

Science.gov (United States)

Feng, Junyan; Wang, Meinan; See, Deven R; Chao, Shiaoman; Zheng, Youliang; Chen, Xianming

2018-06-01

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is an important disease of wheat worldwide. Exploring new resistance genes is essential for breeding resistant wheat cultivars. PI 182103, a spring wheat landrace originally from Pakistan, has shown a high level of resistance to stripe rust in fields for many years, but genes for resistance to stripe rust in the variety have not been studied. To map the resistance gene(s) in PI 182103, 185 recombinant inbred lines (RILs) were developed from a cross with Avocet Susceptible (AvS). The RIL population was genotyped with simple sequence repeat (SSR) and single nucleotide polymorphism markers and tested with races PST-100 and PST-114 at the seedling stage under controlled greenhouse conditions and at the adult-plant stage in fields at Pullman and Mt. Vernon, Washington under natural infection by the stripe rust pathogen in 2011, 2012, and 2013. A total of five quantitative trait loci (QTL) were detected. QyrPI182103.wgp-2AS and QyrPI182103.wgp-3AL were detected at the seedling stage, QyrPI182103.wgp-4DL was detected only in Mt. Vernon field tests, and QyrPI182103.wgp-5BS was detected in both seedling and field tests. QyrPI182103.wgp-7BL was identified as a high-temperature adult-plant resistance gene and detected in all field tests. Interactions among the QTL were mostly additive, but some negative interactions were detected. The 7BL QTL was mapped in chromosomal bin 7BL 0.40 to 0.45 and identified as a new gene, permanently designated as Yr79. SSR markers Xbarc72 and Xwmc335 flanking the Yr79 locus were highly polymorphic in various wheat genotypes, indicating that the molecular markers are useful for incorporating the new gene for potentially durable stripe rust resistance into new wheat cultivars.

Invasive pathogen threatens bird-pine mutualism: implications for sustaining a high-elevation ecosystem.

Science.gov (United States)

McKinney, Shawn T; Fiedler, Carl E; Tomback, Diana F

2009-04-01

Human-caused disruptions to seed-dispersal mutualisms increase the extinction risk for both plant and animal species. Large-seeded plants can be particularly vulnerable due to highly specialized dispersal systems and no compensatory regeneration mechanisms. Whitebark pine (Pinus albicaulis), a keystone subalpine species, obligately depends upon the Clark's Nutcracker (Nucifraga columbiana) for dispersal of its large, wingless seeds. Clark's Nutcracker, a facultative mutualist with whitebark pine, is sensitive to rates of energy gain, and emigrates from subalpine forests during periods of cone shortages. The invasive fungal pathogen Cronartium ribicola, which causes white pine blister rust, reduces whitebark pine cone production by killing cone-bearing branches and trees. Mortality from blister rust reaches 90% or higher in some whitebark pine forests in the Northern Rocky Mountains, USA, and the rust now occurs nearly rangewide in whitebark pine. Our objectives were to identify the minimum level of cone production necessary to elicit seed dispersal by nutcrackers and to determine how cone production is influenced by forest structure and health. We quantified forest conditions and ecological interactions between nutcrackers and whitebark pine in three Rocky Mountain ecosystems that differ in levels of rust infection and mortality. Both the frequency of nutcracker occurrence and probability of seed dispersal were strongly related to annual whitebark pine cone production, which had a positive linear association with live whitebark pine basal area, and negative linear association with whitebark pine tree mortality and rust infection. From our data, we estimated that a threshold level of approximately 1000 cones/ha is needed for a high likelihood of seed dispersal by nutcrackers (probability > or = 0.7), and that this level of cone production can be met by forests with live whitebark pine basal area > 5.0 m2/ha. The risk of mutualism disruption is greatest in northern

cDNA-AFLP analysis reveals differential gene expression in compatible interaction of wheat challenged with Puccinia striiformis f. sp. tritici

Directory of Open Access Journals (Sweden)

Huang Lili

2009-06-01

Full Text Available Abstract Background Puccinia striiformis f. sp. tritici is a fungal pathogen causing stripe rust, one of the most important wheat diseases worldwide. The fungus is strictly biotrophic and thus, completely dependent on living host cells for its reproduction, which makes it difficult to study genes of the pathogen. In spite of its economic importance, little is known about the molecular basis of compatible interaction between the pathogen and wheat host. In this study, we identified wheat and P. striiformis genes associated with the infection process by conducting a large-scale transcriptomic analysis using cDNA-AFLP. Results Of the total 54,912 transcript derived fragments (TDFs obtained using cDNA-AFLP with 64 primer pairs, 2,306 (4.2% displayed altered expression patterns after inoculation, of which 966 showed up-regulated and 1,340 down-regulated. 186 TDFs produced reliable sequences after sequencing of 208 TDFs selected, of which 74 (40% had known functions through BLAST searching the GenBank database. Majority of the latter group had predicted gene products involved in energy (13%, signal transduction (5.4%, disease/defence (5.9% and metabolism (5% of the sequenced TDFs. BLAST searching of the wheat stem rust fungus genome database identified 18 TDFs possibly from the stripe rust pathogen, of which 9 were validated of the pathogen origin using PCR-based assays followed by sequencing confirmation. Of the 186 reliable TDFs, 29 homologous to genes known to play a role in disease/defense, signal transduction or uncharacterized genes were further selected for validation of cDNA-AFLP expression patterns using qRT-PCR analyses. Results confirmed the altered expression patterns of 28 (96.5% genes revealed by the cDNA-AFLP technique. Conclusion The results show that cDNA-AFLP is a reliable technique for studying expression patterns of genes involved in the wheat-stripe rust interactions. Genes involved in compatible interactions between wheat and the

Nanostructure of protective rust layer on weathering steel examined using synchrotron radiation x-rays

International Nuclear Information System (INIS)

Yamashita, Masato; Uchida, Hitoshi; Konishi, Hiroyuki; Mizuki, Jun'ichiro

2004-01-01

The X-ray absorption fine structure (XAFS) spectrum of pure goethite around the Fe K absorption edge and that of the protective rust layer formed on weathering steel exposed for 17 years in an atmospheric environment around the Cr K edge, have been examined using synchrotron radiation X-rays. It was found that the rust layer on the weathering steel mainly consisted of Cr-goethite. By examining the fine structure at the Cr K edge and the Fe K edge, we concluded that Cr 3+ in the rust layer is coordinated with O 2- and is positioned in the double chains of vacant sites in the network of FeO 3 (OH) 3 octahedra in the goethite crystal. This Cr 3+ site indicates that the protective effect of the rust layer is due to the dense aggregation of fine crystals of Cr-goethite with cation selectivity. (author)

Appraisal of wheat germplasm for adult plant resistance against stripe rust

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Saleem Kamran

2015-12-01

Full Text Available The resurgence of wheat stripe rust is of great concern for world food security. Owing to resistance breakdown and the appearance of new virulent high-temperature adapted races of Puccinia striiformis f. sp. tritici (Pst, many high yielding commercial varieties in the country lost their yield potential. Searching for new sources of resistance is the best approach to mitigate the problem. Quantitative resistance (partial or adult plant or durable resistance is reported to be more stable than race specific resistance. In the current perusal, a repertoire of 57 promising wheat lines along with the KLcheck line Morocco, developed through hybridisation and selection of local and international lines with International Maize and Wheat Improvement Center (CIMMYT origin, were evaluated under natural field conditions at Nuclear Institute for Agriculture and Biology (NIAB during the 2012−2013 and 2013−2014 time periods. Final rust severity (FRS, the area under the rust progress curve (AURPC, the relative area under the rust progress curve (rAURPC, and the coefficient of infection (CI were unraveled to infer the level of quantitative resistance. Final rust severity was recorded when the susceptible check exhibited 100% severity. There were 21 lines which were immune (no disease, 16 which were resistant, five moderately resistant, two resistant-to-moderately resistant, one moderately resistant-to-moderately susceptible, 5 moderately susceptible-to-susceptible, one moderately susceptible, and six exhibited a susceptible response. Nevertheless, 51 lines exhibited a high level of partial resistance while the three lines, NW-5-1212-1, NW-7-30-1, and NW-7-5 all showed a moderate level of partial resistance based on FRS, while 54 lines, on the basis of AURPC and rAURPC, were identified as conferring a high level of partial resistance. Moreover, adult plant resistance was conferred by 47 wheat lines, based on CI value. It was striking that, 13 immune lines

Developing proactive management options to sustain bristlecone and limber pine ecosystems in the presence of a non-native pathogen

Science.gov (United States)

A. W. Schoettle

2004-01-01

Limber pine and Rocky Mountain bristlecone pine are currently threatened by the non-native pathogen white pine blister rust (WPBR). Limber pine is experiencing mortality in the Northern Rocky Mountains and the infection front continues to move southward. The first report of WPBR on Rocky Mountain bristlecone pine was made in 2003 (Blodgett and Sullivan 2004), at a site...

Influence of lactate ions on the formation of rust

International Nuclear Information System (INIS)

Sabot, R.; Jeannin, M.; Gadouleau, M.; Guo, Q.; Sicre, E.; Refait, Ph.

2007-01-01

The formation of rust can be simulated by oxidation of aqueous suspensions of Fe(OH) 2 obtained by mixing solutions of NaOH and a Fe(II) salt. The aim of this study was to investigate the influence of organic species associated with microbially influenced corrosion. The lactate anion, often used as a carbon and electrons source for the development of microorganisms, was chosen as an example. Then, in the first part of the study, Fe(OH) 2 was precipitated using iron(II) lactate and NaOH. Its oxidation process involved two stages, as usually observed. The first stage led to a Fe(II-III) intermediate compound, the lactate green rust, GR(C 3 H 5 O 3 - ). This compound has never been reported yet. Its existence demonstrates that the GR structure is able to incorporate a very wide range of anions, whatever the size and geometry. The second stage corresponded to the oxidation of GR(C 3 H 5 O 3 - ). It led to ferrihydrite, the most poorly ordered form of iron(III) oxides and oxyhydroxides. In the second part of the study, the formation of rust in seawater was simulated by oxidation of Fe(OH) 2 in an aqueous media containing both Cl - and SO 4 2- anions. The first stage led to the sulphate green rust, GR(SO 4 2- ), the second stage to lepidocrocite γ-FeOOH. Small amounts of iron(II) lactate were added to the reactants. Lactate ions did not modify the first stage but drastically perturbed the second stage, as ferrihydrite was obtained instead of γ-FeOOH

Adult Plant Leaf Rust Resistance Derived from Toropi Wheat is Conditioned by Lr78 and Three Minor QTL.

Science.gov (United States)

Kolmer, J A; Bernardo, A; Bai, G; Hayden, M J; Chao, S

2018-02-01

Leaf rust caused by Puccinia triticina is an important disease of wheat in many regions worldwide. Durable or long-lasting leaf rust resistance has been difficult to achieve because populations of P. triticina are highly variable for virulence to race-specific resistance genes, and respond to selection by resistance genes in released wheat cultivars. The wheat cultivar Toropi, developed and grown in Brazil, was noted to have long-lasting leaf rust resistance that was effective only in adult plants. The objectives of this study were to determine the chromosome location of the leaf rust resistance genes derived from Toropi in two populations of recombinant inbred lines in a partial Thatcher wheat background. In the first population, a single gene with major effects on chromosome 5DS that mapped 2.2 centimorgans distal to IWA6289, strongly reduced leaf rust severity in all 3 years of field plot tests. This gene for adult plant leaf rust resistance was designated as Lr78. In the second population, quantitative trait loci (QTL) with small effects on chromosomes 1BL, 3BS, and 4BS were found. These QTL expressed inconsistently over 4 years of field plot tests. The adult plant leaf rust resistance derived from Toropi involved a complex combination of QTL with large and small effects.

The formation of green rust induced by tropical river biofilm components

International Nuclear Information System (INIS)

Jorand, F.; Zegeye, A.; Ghanbaja, J.; Abdelmoula, M.

2011-01-01

In the Sinnamary Estuary (French Guiana), a dense red biofilm grows on flooded surfaces. In order to characterize the iron oxides in this biofilm and to establish the nature of secondary minerals formed after anaerobic incubation, we conducted solid analysis and performed batch incubations. Elemental analysis indicated a major amount of iron as inorganic compartment along with organic matter. Solid analysis showed the presence of two ferric oxides ferrihydrite and lepidocrocite. Bacteria were abundant and represented more than 10 11 cells g -1 of dry weight among which iron reducers were revealed. Optical and electronic microscopy analysis revealed than the bacteria were in close vicinity of the iron oxides. After anaerobic incubations with exogenous electron donors, the biofilm's ferric material was reduced into green rust, a Fe II -Fe III layered double hydroxide. This green rust remained stable for several years. From this study and previous reports, we suggest that ferruginous biofilms should be considered as a favorable location for GR biomineralization when redox conditions and electron donors availability are gathered. - Research highlights: → Characterization of ferruginous biofilm components by solid analysis methods. → Lepidocrocite and ferrihydrite were the main iron oxides. → Anaerobic incubation of biofilm with electron donors produced green rust. → Biofilm components promote the formation of the green rust. → Ferruginous biofilm could contribute to the natural mercury attenuation.

The formation of green rust induced by tropical river biofilm components

Energy Technology Data Exchange (ETDEWEB)

Jorand, F., E-mail: jorand@pharma.uhp-nancy.fr [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME) UMR 7564, CNRS-Nancy-Universite, Institut Jean Barriol, 405 rue de Vandoeuvre, F-54600 Villers-les Nancy (France); Zegeye, A. [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME) UMR 7564, CNRS-Nancy-Universite, Institut Jean Barriol, 405 rue de Vandoeuvre, F-54600 Villers-les Nancy (France); Ghanbaja, J. [Service Commun de Microscopies Electroniques et Microanalyses X (SCMEM), Nancy-Universite, Bvd des Aiguillettes, BP 239, 54506, Vandoeuvre-les-Nancy (France); Abdelmoula, M. [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME) UMR 7564, CNRS-Nancy-Universite, Institut Jean Barriol, 405 rue de Vandoeuvre, F-54600 Villers-les Nancy (France)

2011-06-01

In the Sinnamary Estuary (French Guiana), a dense red biofilm grows on flooded surfaces. In order to characterize the iron oxides in this biofilm and to establish the nature of secondary minerals formed after anaerobic incubation, we conducted solid analysis and performed batch incubations. Elemental analysis indicated a major amount of iron as inorganic compartment along with organic matter. Solid analysis showed the presence of two ferric oxides ferrihydrite and lepidocrocite. Bacteria were abundant and represented more than 10{sup 11} cells g{sup -1} of dry weight among which iron reducers were revealed. Optical and electronic microscopy analysis revealed than the bacteria were in close vicinity of the iron oxides. After anaerobic incubations with exogenous electron donors, the biofilm's ferric material was reduced into green rust, a Fe{sup II}-Fe{sup III} layered double hydroxide. This green rust remained stable for several years. From this study and previous reports, we suggest that ferruginous biofilms should be considered as a favorable location for GR biomineralization when redox conditions and electron donors availability are gathered. - Research highlights: {yields} Characterization of ferruginous biofilm components by solid analysis methods. {yields} Lepidocrocite and ferrihydrite were the main iron oxides. {yields} Anaerobic incubation of biofilm with electron donors produced green rust. {yields} Biofilm components promote the formation of the green rust. {yields} Ferruginous biofilm could contribute to the natural mercury attenuation.

Rust types from JSON samples - Approximating type providers with procedural macros in Rust

OpenAIRE

Vesteraas, Erik Andreas

2017-01-01

When programmers access external data in a statically typed programming language, they are often faced with a dilemma between convenient and type-safe access to the data. In the programming language F#, a concept called type providers has been proposed as a solution to this problem by having compiler support for libraries with the capability to generate types at compile time. This thesis presents "json_typegen", a project which aims to show the feasibility of similar solutions in the Rust pro...

Overview of the functional virulent genome of the coffee leaf rust pathogen Hemileia vastatrix with an emphasis on early stages of infection

Directory of Open Access Journals (Sweden)

Pedro eTalhinhas

2014-03-01

Full Text Available Hemileia vastatrix is the causal agent of coffee leaf rust, the most important disease of coffee (Coffea arabica. In this work, a 454-pyrosequencing transcriptome analysis of H. vastatrix germinating urediniospores (gU and appressoria (Ap was performed and compared to previously published in planta haustoria-rich (H data. A total of 9234 transcripts were identified and annotated. Ca. 50% of these transcripts showed no significant homology to international databases. Only 784 sequences were shared by the three conditions, and 75% were exclusive of either gU (2146, Ap (1479 or H (3270. Relative transcript abundance and RT-qPCR analyses for a selection of genes indicated a particularly active metabolism, translational activity and production of new structures in the appressoria and intense signalling, transport, secretory activity and cellular multiplication in the germinating urediniospores, suggesting the onset of a plant-fungus dialogue as early as at the germ tube stage. Gene expression related to the production of carbohydrate-active enzymes and accumulation of glycerol in germinating urediniospores and appressoria suggests that combined lytic and physical mechanisms are involved in appressoria-mediated penetration. Besides contributing to the characterisation of molecular processes leading to appressoria-mediated infection by rust fungi, these results point towards the identification of new H. vastatrix candidate virulence factors, with 516 genes predicted to encode secreted proteins.

CHEMICAL INTERACTIONS OF ARSENATE, ARSENITE, PHOSPHATE, AND SILICATE WITH IRON (II, III) HYDROXYCARBONATE GREEN RUST

Science.gov (United States)

Granular zerovalent iron has been proposed to be used as a medium in permeable reactive barriers (PRBs) to remove arsenic from contaminated groundwater. Iron(II, III) hydroxycarbonate green rust (carbonate green rust, or CGR) is a major corrosion product of zerovalent iron under ...

WHEAT PATHOGEN RESISTANCE AND CHITINASE PROFILE

Directory of Open Access Journals (Sweden)

Zuzana Gregorová

2015-02-01

Full Text Available The powdery mildew and leaf rust caused by Blumeria graminis and Puccinia recondita (respectively are common diseases of wheat throughout the world. These fungal diseases greatly affect crop productivity. Incorporation of effective and durable disease resistance is an important breeding objective for wheat improvement. We have evaluated resistance of four bread wheat (Triticum aestivum and four spelt wheat (Triticum spelta cultivars. Chitinases occurrence as well as their activity was determined in leaf tissues. There was no correlation between resistance rating and activity of chitinase. The pattern of chitinases reveals four isoforms with different size in eight wheat cultivars. A detailed understanding of the molecular events that take place during a plant–pathogen interaction is an essential goal for disease control in the future.

Difference between Cr and Ni K-edge XANES spectra of rust layers formed on Fe-based binary alloys exposed to Cl-rich environment

International Nuclear Information System (INIS)

Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

2005-01-01

The rust layer formed on weathering steel possesses a strong protective ability against corrosives in an atmospheres. This ability is related to the structure of the rust layer. The difference in the protective ability of a rust layer. The difference in the protective ability of a rust layer in a Cl-rich environment between conventional weathering steel containing Cr and advanced weathering steel containing Ni is believed to be caused by the differences in local structural and chemical properties between alloying elements. Cr and Ni, in the rust layer. In order to examine the effect of these alloying elements on the structure of the rust layer formed on steel in a Cl-rich environment, we have performed Cr and Ni K-edge X-ray absorption near-edge structure (XANES) measurements for the rust layer of Fe-Cr and Fe-Ni binary alloys exposed to a Cl-rich atmosphere using synchrotron radiation. The results of the Cr K-edge XANES measurements for the rust layer of Fe-Cr binary alloys show that the atomic geometry around Cr depends on the concentration of Cr. Therefore, it is expected that the local structure around Cr in the rust layer is unstable. On the other hand, from the results of the Ni K-edge XANES measurements for the rust layer of Fe-Ni binary alloys. Ni is considered to be positioned at a specific site in the crystal structure of a constituent of the rust layer, such as akaganeite or magnetite. As a consequence, Ni negligibly interacts with Cl - ions in the rust layer. (author)

High-resolution mapping reveals linkage between genes in common bean cultivar Ouro Negro conferring resistance to the rust, anthracnose, and angular leaf spot diseases.

Science.gov (United States)

Valentini, Giseli; Gonçalves-Vidigal, Maria Celeste; Hurtado-Gonzales, Oscar P; de Lima Castro, Sandra Aparecida; Cregan, Perry B; Song, Qijian; Pastor-Corrales, Marcial A

2017-08-01

Co-segregation analysis and high-throughput genotyping using SNP, SSR, and KASP markers demonstrated genetic linkage between Ur-14 and Co-3 4 /Phg-3 loci conferring resistance to the rust, anthracnose and angular leaf spot diseases of common bean. Rust, anthracnose, and angular leaf spot are major diseases of common bean in the Americas and Africa. The cultivar Ouro Negro has the Ur-14 gene that confers broad spectrum resistance to rust and the gene cluster Co-3 4 /Phg-3 containing two tightly linked genes conferring resistance to anthracnose and angular leaf spot, respectively. We used co-segregation analysis and high-throughput genotyping of 179 F 2:3 families from the Rudá (susceptible) × Ouro Negro (resistant) cross-phenotyped separately with races of the rust and anthracnose pathogens. The results confirmed that Ur-14 and Co-3 4 /Phg-3 cluster in Ouro Negro conferred resistance to rust and anthracnose, respectively, and that Ur-14 and the Co-3 4 /Phg-3 cluster were closely linked. Genotyping the F 2:3 families, first with 5398 SNPs on the Illumina BeadChip BARCBEAN6K_3 and with 15 SSR, and eight KASP markers, specifically designed for the candidate region containing Ur-14 and Co-3 4 /Phg-3, permitted the creation of a high-resolution genetic linkage map which revealed that Ur-14 was positioned at 2.2 cM from Co-3 4 /Phg-3 on the short arm of chromosome Pv04 of the common bean genome. Five flanking SSR markers were tightly linked at 0.1 and 0.2 cM from Ur-14, and two flanking KASP markers were tightly linked at 0.1 and 0.3 cM from Co-3 4 /Phg-3. Many other SSR, SNP, and KASP markers were also linked to these genes. These markers will be useful for the development of common bean cultivars combining the important Ur-14 and Co-3 4 /Phg-3 genes conferring resistance to three of the most destructive diseases of common bean.

Putting Ug99 on the map: An update on current and future monitoring

DEFF Research Database (Denmark)

Hodson, D P; Nazari, K; Park, R F

2011-01-01

Detection of stem rust race TTKSK (Ug99) from Uganda in 1998/99 highlighted not only the extremely high vulnerability of the global wheat crop to stem rust but also a lack of adequate global systems to monitor such a threat. Progress in the development and expansion of the Global Cereal Rust...... Monitoring System (GCRMS) is described. The current situation regarding the Ug99 lineage of races is outlined and the potential for expansion into important wheat areas is considered. The GCRMS has successfully tracked the spread and changes that are occurring within the Ug99 lineage and is now well...... capacity for race analysis is seen to be critical and integration of the Global Rust Reference Centre into the stem rust monitoring network is seen as a positive development. The current acute situation with severe epidemics of stripe rust in many countries indicates a clear need for more effective global...

Rust Layer Formed on Low Carbon Weathering Steels with Different Mn, Ni Contents in Environment Containing Chloride Ions

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Gui-qin FU

2016-11-01

Full Text Available The rusting evolution of low carbon weathering steels with different Mn, Ni contents under a simulated environment containing chloride ions has been investigated to clarify the correlation between Mn, Ni and the rust formed on steels. The results show that Mn contents have little impact on corrosion kinetics of experimental steels. Content increase of Ni both enhances the anti-corrosion performance of steel substrate and the rust. Increasing Ni content is beneficial to forming compact rust. Semi-quantitative XRD phase analysis shows that the quantity ratio of α/γ*（α-FeOOH/(γ-FeOOH+Fe3O4 decreases as Mn content increases but it increases as Ni content increases. Ni enhances rust layer stability but Mn content exceeding 1.06 wt.% is disadvantageous for rust layer stability. The content increase of Mn does not significantly alter the parameters of the polarization curve. However, as Ni contents increases, Ecorr has shifted to the positive along with decreased icorr values indicating smaller corrosion rate especially as Ni content increases from 0.42 wt.% to 1.50 wt.%.DOI: http://dx.doi.org/10.5755/j01.ms.22.4.12844

Prediction of yield losses in wheat (triticum aestivum l.) caused by yellow rust in relation to epidemiological factors in Faisalabad

International Nuclear Information System (INIS)

Ahmad, S.; Afzal, M.; Noorka, I.R.; Iqbal, Z.; Akhtar, N.; Iiftikhar, Y.; Kamran, M.

2010-01-01

Thirty six genotypes were screened against yellow rust to check their level of susceptibility or resistance. Among 36 genotypes screened against yellow rust, 18 were susceptible, 6 were moderately susceptible to susceptible, 7 were moderately resistant to moderately susceptible and 5 genotypes remained resistant. Yield losses were predicted in wheat on the basis of varying level of yellow rust severities. It was observed that susceptible genotypes showed higher yield losses as compared to resistant genotypes. Maximum severity of 90% of yellow rust resulted in 54% to 55% calculated and predicted losses, respectively. While 40, 50, 60 and 70% disease severity of yellow rust caused 35-34%, 38-37%, 42-40% and 46-47% calculated and predicted losses, respectively. However, the decline in losses was observed as the genotypes changed their reaction from susceptible to moderate susceptible. Similarly, losses were diminished as the varieties/lines showed moderate resistant reaction from moderate susceptible. Minimum temperature and relative humidity remained positively correlated while the maximum temperature showed negative correlation with stripe rust severity. With the increase of minimum temperature and relative humidity a rise up in stripe rust infection was seen while as the maximum temperature increased stripe rust infection decreased on different genotypes. It may be concluded from the study that environmental factors played major role in the spread of the disease which result in yield losses. (author)

Influence of Rust Permeability on Corrosion of E690 Steel in Industrial and Non-industrial Marine Splash Zones

Science.gov (United States)

Chen, Mindong; Pang, Kun; Liu, Zhiyong; Wu, Junsheng; Li, Xiaogang

2018-05-01

The corrosion behaviour of E690 steel in industrial and non-industrial marine splash environments was studied by environmental testing, morphology analysis, electrochemical measurements, and scanning Kelvin probe microscopy. Chloride and sulphide anions were found to diffuse across the rust layer following the evaporation of seawater splashed on the steel's surface. The cation-selective permeability of the rust layer resulted in an anion concentration gradient across the rust layer, which was more significant in the presence of sulphur dioxide. In addition, sulphur dioxide enhanced the formation of α-FeOOH, which led to the formation of distinct anode and cathode areas at the rust/steel interface.

Breeding wheat for disease resistance in Kenya

International Nuclear Information System (INIS)

Njau, P.N.; Kinyua, M.G.; Karanja, L.; Maling'a, J.

2001-01-01

Yellow rust caused by Puccinia striformis and stem rust caused by Puccinia graminis tritici are most destructive diseases in Kenya. In wheat improvement, development of varieties of wheat with resistance to these diseases has been among the foremost contributions in wheat breeding. In breeding programs each disease is considered as a separate problem. Attention has been given to varieties resistant to stem rust, yellow rust and leaf rust among other diseases. In the year 2001 program stem rust and yellow rust were recorded in all the sites where NPT was performed. Breeding for resistance for the two diseases is approached through the Introductions and Hybridisation. The Doubled Haploid Technique is used to quicken the time of homozygous lines production. The introduction and the homozygous lines are then evaluated for yield and disease resistance in the field under preliminary yield trials and the National Performance Trials (NPT) in 2001, 18 lines and 2 check varieties were included in the NPT. The results show that there were some differences in reaction to the three diseases where lines R946, K7972-1 and R899 had the lowest score of the diseases in all sites. In the commercial variety trial the results show that all the varietieshave become susceptible to stem rust and so the need to develop new cultivars which will be resistance to the rusts. Yombi a newly developed variety showed a substantially high level resistance. (author)

Evidence for Increased Aggressiveness in a Recent Widespread Strain of Puccinia striiformis f. sp. tritici Causing Stripe Rust of Wheat

DEFF Research Database (Denmark)

Milus, Eugene A; Kristensen, Kristian; Hovmøller, Mogens S

2009-01-01

Stripe rust (yellow rust) of wheat, caused by Puccinia striiformis f. sp. tritici, has become more severe in eastern United States, Australia, and elsewhere since 2000. Recent research has shown that this coincided with a global spread of two closely related strains that were similar based on vir...... that wheat rust fungi can adapt to warmer temperatures and cause severe disease in previously unfavorable environments......Stripe rust (yellow rust) of wheat, caused by Puccinia striiformis f. sp. tritici, has become more severe in eastern United States, Australia, and elsewhere since 2000. Recent research has shown that this coincided with a global spread of two closely related strains that were similar based...... regimes for latent period, lesion length, lesion width, lesion area, and spore production on adult plants of a susceptible wheat cultivar with no known genes for resistance to stripe rust. "New" isolates (since 2000) were significantly more aggressive than "old" isolates (before 2000) for all variables...

Genome-Wide Association Mapping for Resistance to Leaf and Stripe Rust in Winter-Habit Hexaploid Wheat Landraces.

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Albert Kertho

Full Text Available Leaf rust, caused by Puccinia triticina (Pt, and stripe rust, caused by P. striiformis f. sp. tritici (Pst, are destructive foliar diseases of wheat worldwide. Breeding for disease resistance is the preferred strategy of managing both diseases. The continued emergence of new races of Pt and Pst requires a constant search for new sources of resistance. Here we report a genome-wide association analysis of 567 winter wheat (Triticum aestivum landrace accessions using the Infinium iSelect 9K wheat SNP array to identify loci associated with seedling resistance to five races of Pt (MDCL, MFPS, THBL, TDBG, and TBDJ and one race of Pst (PSTv-37 frequently found in the Northern Great Plains of the United States. Mixed linear models identified 65 and eight significant markers associated with leaf rust and stripe rust, respectively. Further, we identified 31 and three QTL associated with resistance to Pt and Pst, respectively. Eleven QTL, identified on chromosomes 3A, 4A, 5A, and 6D, are previously unknown for leaf rust resistance in T. aestivum.

Modification of tolerance of oats to crown rust induced by chemical mutagens

International Nuclear Information System (INIS)

Simons, M.D.; Browning, J.A.; Frey, K.J.

1983-01-01

Seeds of crown rust (Puccinia coronata) susceptible cultivated oats (Avena sativa) were treated with the mutagenic chemical ethyl methanesulphonate (EMS), and pure lines derived from these treated seeds were tested in later generations for the relative amount of reduction in yield and seed weight caused by crown rust infection. In the absence of crown rust, the yield of most of the treated lines was greatly reduced. The overall means of the treated lines for both yield and seed weight response to infection were significantly lower than the control, but 10 lines significantly exceeded the control for yield response and 15 exceeded it for seed weight response. Recurrent EMS treatment of once-treated lines rated as tolerant resulted in groups of lines that were more tolerant, on the average, than groups of lines from recurrently treated lines rated as susceptible. A few of the recurrently treated individual lines derived from tolerant parents had a higher degree of tolerance than their parental lines. EMS treatment of diploid (A. strigosa) and tetraploid (A. abyssinica) oats resulted in groups of lines showing significant genetic variance for response to crown rust, indicating that treatment had induced real genetic change. A few diploid lines were a little more tolerant than their control, but none of the tetraploid lines showed any consistent improvement. (author)

Marker-assisted pyramiding of Thinopyrum-derived leaf rust ...

Indian Academy of Sciences (India)

Mona Singh

2017-12-08

Dec 8, 2017 ... Abstract. This study was undertaken to pyramid two effective leaf rust resistance genes (Lr19 and Lr24) derived from ... genes such as Lr9, Lr19, Lr26 and Lr28 became ineffective ..... Disease management recommendations.

De Novo Assembly and Phasing of Dikaryotic Genomes from Two Isolates of Puccinia coronata f. sp. avenae, the Causal Agent of Oat Crown Rust.

Science.gov (United States)

Miller, Marisa E; Zhang, Ying; Omidvar, Vahid; Sperschneider, Jana; Schwessinger, Benjamin; Raley, Castle; Palmer, Jonathan M; Garnica, Diana; Upadhyaya, Narayana; Rathjen, John; Taylor, Jennifer M; Park, Robert F; Dodds, Peter N; Hirsch, Cory D; Kianian, Shahryar F; Figueroa, Melania

2018-02-20

molecular mechanisms underpinning pathogenicity and the emergence of new virulence traits are lacking. Such limitations are partly due to the obligate biotrophic lifestyle of P. coronata f. sp. avenae as well as the dikaryotic nature of the genome, features that are also shared with other important rust pathogens. This study reports the first release of a haplotype-phased genome assembly for a dikaryotic fungal species and demonstrates the amenability of using emerging technologies to investigate genetic diversity in populations of P. coronata f. sp. avenae . Copyright © 2018 Miller et al.

Gene effects and combining ability in some bread wheat genotypes to yellow rust disease.

Science.gov (United States)

Razavi, A R; Taeb, M; Afshari, F; Khavari, S; Abbaspoor, M

2009-01-15

Ten wheat lines were studied to determine gene effects and combining ability in some bread wheat genotypes to yellow rust disease. Ten parental lines and F1 were evaluated in a randomized complete block design with three replications in Agricultural and Natural Resources Research Center, Mashhad, Iran. Two races (134E134A+ and 4E0A+) were used for this study. Latent Period (LP) and Infection Type (IT) were measured in the field and greenhouse. Results showed significant differences between races in their pathogenicity and between genotypes in their resistance to the pathogen. Diallel cross carried out between the parents and progenies and thereafter were analyzed by the method of Griffing and Haymans. The General Combining Ability (GCA) and Special Combining Ability (SCA) for all traits were significant and showed additive variance was more important. Test for validity of diallel hypothesis proved epistasis effect for all traits. P1, P2 and F1 showed significant difference between all traits in generations mean analysis. Average degree of dominance ranged from partial to over dominance for resistance or susceptibility. Dominance, additive and epistatic types of gene action were responsible for the genetic control of the traits. However, except for additive-additive component, non-additive effect of genes could not be fixed by self-fertilization.

FLUXAPYROXAD IN THE ASIAN SOYBEAN RUST CONTROL IN THE CERRADO BIOME

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RAFAEL MENEZES SILVA DE FREITAS

2016-01-01

Full Text Available The etiologic agent of the Asian soybean rust is the Phakopsora pachyrhizi, which causes a reduction in the photosynthetic leaf area and, consequently, in the crop yield. Chemical control is one of the main measures for its management. The objective of this work was to evaluate the efficacy and selectivity of the fluxapyroxad fungicide on controlling the Asian soybean rust, under the edaphoclimatic conditions of the Cerrado biome. The experiment was conducted in an area under no-tillage system, in the Agricultural Research Center, Rio Verde, Goias, Brazil, during the 2012/2013 crop season, using the cultivar NA7337. A randomized block experimental design was used, with twelve treatments and four replications. The treatments consisted of applications of fluxapyroxad (FX, pyraclostrobin (PT, epoxiconazole (EX and metconazole (MZ. The average severity of the disease in the plants reached 37% in the Control. All treatments with fungicides differed from the Control. Treatments 9, 10, 11 and 12 provided the greatest rates of soybean rust control. The treatments 10, 11 and 12 had the highest thousand grain weights, and the yields of the treatments 2, 3 and 11, despite higher than the Control, were lower than the treatments 4, 5, 6, 7, 8, 9, 10 and 12, which had statistically equal yields. The increasing in yield, compared to the Control, ranged from 10.05% (pyraclostrobin, epoxiconazole + pyraclostrobin + mineral oil to 30.55% (pyraclostrobin, pyraclostrobin + fluxapyroxad + mineral oil and pyraclostrobin + metconazole + mineral oil. The highest rates of soybean rust control were presented by fungicides containing fluxapyroxad.

Corrosion-resistant amorphous alloy ribbons for electromagnetic filtration of iron rusts from water

International Nuclear Information System (INIS)

Kawashima, Asahi; Asami, Katsuhiko; Sato, Takeaki; Hashimoto, Koji

1985-01-01

An attempt was made to use corrosion-resistant amorphous Fe-9Cr-13P-7C alloy ribbons as an electromagnetic filter material for trapping various iron rusts suspended in water at 40 0 C. The ferrimagnetic Fe 3 O 4 rust was trapped with the 100 % efficiency and paramagnetic rusts such as α-Fe 2 O 3 , α-FeOOH and amorphous ferric oxyhydroxide were trapped with certain efficiencies at the magnetic field strength of 0.5-10 kOe. The regeneration of the filter by back-washing was easy. The trapping capacity of electromagnetic filter was proportional to the edge length of the filter material where the high magnetic field strength existed. Therefore, melt-spun thin and narrow amorphous alloy ribbons having the high corrosion resistance have the potential utility as electromagnetic filter material. (author)

Biology and pathology of Ribes and their implications for management of white pine blister rust

Science.gov (United States)

P. J. Zambino

2010-01-01

Ribes (currants and gooseberries) are telial hosts for the introduced and invasive white pine blister rust fungus, Cronartium ribicola. Knowledge of wild and introduced Ribes helps us understand the epidemiology of blister rust on its aecial hosts, white pines, and develop disease control and management strategies. Ribes differ by species in their contribution to...

Kinetics of structural rust transformation in environments containing chloride and SO2

Directory of Open Access Journals (Sweden)

Valencia, A.

2003-12-01

Full Text Available The behavior of the rusts produced on low carbon steel exposed in industrial atmospheres, at different distances from the sea, was studied by simulating the wetting-drying cycle in a CEBELCOR type apparatus. Coupons electrode potential was monitored and rust layer was analyzed by gravimetric techniques, optical microscopy and Mössbauer spectroscopy. A particular chloride/sulfur ratio in the atmosphere was found, for which there is a particular behavior in rust formation. For this ratio, corrosion rates were much less than expected. It is postulated a kinetic mechanism for rust layer formation as the origin of this special behavior. An electrode potential similar to that in a weathering steel was observed, this is reflected in the low corrosion rate obtained. The proposed kinetic mechanism for rust formation under these exposure conditions enables new research lines on layer formation and the development of protective rust for industrial marine atmospheres.Se estudió el comportamiento de las herrumbres de un acero de bajo carbono expuesto en la simulación de atmósferas industriales con diferentes distancias al mar, con del ciclo de humectación y secado en el ensayo CEBELCOR y en soluciones representativas de las atmósferas en cuestión. Se hizo seguimiento del potencial de electrodo de los cuerpos de prueba y se analizó la capa de productos de corrosión por técnicas gravimétricas, microscopía óptica y espectroscopia Mössbauer. Se determinó un valor de cloruros y sulfatos en la atmósfera que genera un comportamiento particular en la formación de la herrumbre, presentando velocidades de corrosión menores a las esperadas para el tenor de agentes agresivos, y se postuló un mecanismo cinético en la formación de la película como causante del fenómeno particular. Se observó un comportamiento del potencial próximo al de un acero autoprotector, que se refleja en una menor velocidad de corrosión. La propuesta del mecanismo cin

Screening for sugarcane brown rust in first clonal stage of the Canal Point sugarcane breeding program

Science.gov (United States)

Sugarcane (Saccharum spp.) brown rust (caused by Puccinia melanocephala H. & P. Sydow) was first reported in the United States in 1978 and is still one of great challenges for sugarcane production. A better understanding of sugarcane genotypic variation in response to brown rust will help optimize b...

A baseline analysis of the distribution, host-range, and severity of the rust Puccinia Psidii in the Hawaiian islands, 2005-2010

Science.gov (United States)

Anderson, Robert C.

2012-01-01

Puccinia psidii was first described by Winter (1884) on guava (Psidium guajava L.) in Brazil. The rust is still a major pest of native guava in Brazil and is often referred to as “guava rust” internationally. It is unusual among rust fungi because of its broad and ever-expanding host-range within the Myrtaceae plant family (Simpson et al. 2006). The pathogen is regarded as a major threat to Eucalyptus plantations and other Myrtaceae worldwide (Coutinho et al. 1998, Grgurinovic et al. 2006, Glen et al. 2007). Infections of leaves and meristems are particularly severe on susceptible seedlings, cuttings, young trees, and coppice, causing plants to be stunted and multi-branched, inhibiting normal growth and development, and sometimes causing death to young seedlings (Booth et al. 2000, Rayachhetry et al. 2001). The fungus has expanded its host-range in Brazil, affecting both native and introduced Myrtaceae (Coutinho et al. 1998). Since its discovery in 1884, P. psidii has continually been discovered to have an expanding host-range within the Myrtaceae, affecting hosts throughout much of South and Central America and the Caribbean. Spreading out originally from Brazil in 1884, the fungus has been reported on hosts in the following countries (first record in parentheses): Paraguay (1884), Uruguay (1889), Ecuador (1891), Colombia (1913), Puerto Rico (1913), Cuba (1926), Dominican Republic (1933), Venezuela (1934), Jamaica (1936), Argentina (1946), Dominica (1948), Trinidad and Tobago (1951), Guatemala (1968), United States (Florida; 1977), Mexico (1981), El Salvador (1987), and Costa Rica (1998) (Simpson et al. 2006). It is possible that P. psidii was present in El Salvador and Costa Rica prior to 1980, but was not reported until 1987 and 1998, respectively. Until recently, Puccinia psidii was restricted to the Neotropics, Mexico, and the state of Florida in the United States. While the rust has been present in Florida for over 30 years, only recently has it spread

Blister rust in North America: What we have not learned in the past 100 years

Science.gov (United States)

Eugene P. Van Arsdel; Brian W. Geils

2011-01-01

Introduction of Cronartium ribicola (white pine blister rust) greatly motivated development of tree disease control and research in America. Although foresters and pathologists have learned much in the past 100 years, more remains to learn. The most important lesson is that fear of blister rust has reduced pine regeneration more than the disease itself. Based on six...

Wheat TaRab7 GTPase is part of the signaling pathway in responses to stripe rust and abiotic stimuli.

Directory of Open Access Journals (Sweden)

Furong Liu

Full Text Available Small GTP-binding proteins function as regulators of specific intercellular fundamental biological processes. In this study, a small GTP-binding protein Rab7 gene, designated as TaRab7, was identified and characterized from a cDNA library of wheat leaves infected with Puccinia striiformis f. sp. tritici (Pst the wheat stripe rust pathogen. The gene was predicted to encode a protein of 206 amino acids, with a molecular mass of 23.13 KDa and an isoeletric point (pI of 5.13. Further analysis revealed the presence of a conserved signature that is characteristic of Rab7, and phylogenetic analysis demonstrated that TaRab7 has the highest similarity to a small GTP binding protein gene (BdRab7-like from Brachypodium distachyon. Quantitative real-time PCR assays revealed that the expression of TaRab7 was higher in the early stage of the incompatible interactions between wheat and Pst than in the compatible interaction, and the transcription level of TaRab7 was also highly induced by environmental stress stimuli. Furthermore, knocking down TaRab7 expression by virus induced gene silencing enhanced the susceptibility of wheat cv. Suwon 11 to an avirulent race CYR23. These results imply that TaRab7 plays an important role in the early stage of wheat-stripe rust fungus interaction and in stress tolerance.

Characterisation of Triticum vavilovii-derived stripe rust resistance using genetic, cytogenetic and molecular analyses and its marker-assisted selection.

Science.gov (United States)

Bariana, H. S.; Brown, G. N.; Ahmed, N. U.; Khatkar, S.; Conner, R. L.; Wellings, C. R.; Haley, S.; Sharp, P. J.; Laroche, A.

2002-02-01

Stripe rust resistance was identified in Triticum vavilovii( T. vaviloviiAus22498)-derived Russian wheat aphid (RWA)-resistant germplasm. Inheritance studies indicated monogenic control of resistance. The resistance gene was tentatively designated as Yrvav and was located on chromosome 1B by monosomic analysis. A close association (1.5+/-0.9% recombination) of Yrvav with a T. vavilovii-derived gliadin allele ( Gli-B1vav) placed it in chromosome arm 1BS. Yrvavwas allelic with Yr10. Tests with Yr10 avirulent and virulent pathotypes showed that Yrvav and Yr10 possess identical pathogenic specificity. Yrvav and Yr10 showed close genetic associations with alternate alleles at the Xpsp3000(microsatellite marker), Gli-B1 and Rg1 loci. Based on these observations Yrvav was named as Yr10vav. The close association between Xpsp3000 and Gli-B1 was also confirmed. The Yr10vav-linked Xpsp3000 allele (285 bp) was not present in 65 Australian cultivars, whereas seven Australian wheats lacking Yr10 carried the same Xpsp3000 allele (260 bp) as Yr10carrying wheat cultivar Moro. Xpsp3000 and/or Gli-B1 could be used in marker-assisted selection for pyramiding Yr10vavor Yr10 with other stripe rust resistance genes. Yr10vav was inherited independently of the T. vavilovii-derived RWA resistance.

Morphology and AFLP markers suggest three Hordeum chilense ecotypes that differ in avoidance to rust fungi

NARCIS (Netherlands)

Vaz Patto, M.C.; Aardse, A.; Buntjer, J.; Rubiales, D.; Martin, A.; Niks, R.E.

2001-01-01

In Hordeum chilense Roem. & Schult., a high variation in the level of avoidance to infection of barley leaf rust (Puccinia hordei Otth) occurs. Probably resulting from the properties of the stomata, the rust germ tube overgrows stomata, and the infection process fails in an early stage. In the

A rapid genotyping method for an obligate fungal pathogen, Puccinia striiformis f.sp. tritici, based on DNA extraction from infected leaf and Multiplex PCR genotyping

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Enjalbert Jérôme

2011-07-01

Full Text Available Abstract Background Puccinia striiformis f.sp. tritici (PST, an obligate fungal pathogen causing wheat yellow/stripe rust, a serious disease, has been used to understand the evolution of crop pathogen using molecular markers. However, numerous questions regarding its evolutionary history and recent migration routes still remains to be addressed, which need the genotyping of a large number of isolates, a process that is limited by both DNA extraction and genotyping methods. To address the two issues, we developed here a method for direct DNA extraction from infected leaves combined with optimized SSR multiplexing. Findings We report here an efficient protocol for direct fungal DNA extraction from infected leaves, avoiding the costly and time consuming step of spore multiplication. The genotyping strategy we propose, amplified a total of 20 SSRs in three Multiplex PCR reactions, which were highly polymorphic and were able to differentiate different PST populations with high efficiency and accuracy. Conclusion These two developments enabled a genotyping strategy that could contribute to the development of molecular epidemiology of yellow rust disease, both at a regional or worldwide scale.

Agricultural pathogen decontamination technology-reducing the threat of infectious agent spread.

Energy Technology Data Exchange (ETDEWEB)

Betty, Rita G.; Bieker, Jill Marie; Tucker, Mark David

2005-10-01

Outbreaks of infectious agricultural diseases, whether natural occurring or introduced intentionally, could have catastrophic impacts on the U.S. economy. Examples of such agricultural pathogens include foot and mouth disease (FMD), avian influenza (AI), citrus canker, wheat and soy rust, etc. Current approaches to mitigate the spread of agricultural pathogens include quarantine, development of vaccines for animal diseases, and development of pathogen resistant crop strains in the case of plant diseases. None of these approaches is rapid, and none address the potential persistence of the pathogen in the environment, which could lead to further spread of the agent and damage after quarantine is lifted. Pathogen spread in agricultural environments commonly occurs via transfer on agricultural equipment (transportation trailers, tractors, trucks, combines, etc.), having components made from a broad range of materials (galvanized and painted steel, rubber tires, glass and Plexiglas shields, etc), and under conditions of heavy organic load (mud, soil, feces, litter, etc). A key element of stemming the spread of an outbreak is to ensure complete inactivation of the pathogens in the agricultural environment and on the equipment used in those environments. Through the combination of enhanced agricultural pathogen decontamination chemistry and a validated inactivation verification methodology, important technologies for incorporation as components of a robust response capability will be enabled. Because of the potentially devastating economic impact that could result from the spread of infectious agricultural diseases, the proposed capability components will promote critical infrastructure protection and greater border and food supply security. We investigated and developed agricultural pathogen decontamination technologies to reduce the threat of infectious-agent spread, and thus enhance agricultural biosecurity. Specifically, enhanced detergency versions of the patented

Genetics of leaf rust resistance in the hard red winter wheat cultivars Santa Fe and Duster

Science.gov (United States)

Leaf rust caused by Puccinia triticina is a common and important disease of hard red winter wheat in the Great Plains of the United States. The hard red winter wheat cultivars 'Santa Fe' and 'Duster' have had effective leaf rust resistance since their release in 2003 and 2006, respectively. Both cul...

Localising QTLs for leaf rust resistance and agronomic traits in barley (¤Hordeum vulgare¤ L.)

DEFF Research Database (Denmark)

Kicherer, S.; Backes, G.; Walther, U.

2000-01-01

to leaf rust by means of artificial infection, heading date, plant height and Kernel weight were assessed. For leaf rust resistance, 4 QTLs were localised, that explained 96.1% of the genetic variation. One QTL on chromosome 4H confirmed a position found in another genetic background and one mapped...

Moessbauer spectroscopic study of rust formed on a weathering steel and a mild steel exposed for a long term in an industrial environment

International Nuclear Information System (INIS)

Kamimura, Takayuki; Nasu, Saburo; Tazaki, Takashi; Kuzushita, Kaori; Morimoto, Shotaro

2002-01-01

The rusts formed on mild steel (15-year exposure) and weathering steel (32-year exposure) exposed to an industrial environment have been characterized by means of X-ray diffraction technique and 57 Fe Moessbauer spectroscopy. By using an X-ray diffraction method, it is suggested that the rusts formed on both steels consist of the crystalline α-FeOOH, γ-FeOOH and an X-ray amorphous phase, which gives no peak to X-ray diffraction pattern. The amount of the X-ray amorphous phase exceeds 50% of the total amount of the rust. The 57 Fe Moessbauer spectra observed at 10K indicate that the rust contains only α-FeOOH, γ-FeOOH and Fe 3-δ O 4 (γ-Fe 2 O 3 ) for mild steel, and only α-FeOOH and γ-FeOOH for weathering steel. The X-ray amorphous substance in the rust payer formed on mild steel possesses the structures of mainly α-FeOOH showing superparamagnetism owing to its small particle size, and Fe 3-δ O 4 (γ-Fe 2 O 3 ). They are contained both in the inner rust layer and in the outer rust layer. The X-ray amorphous phase in the rust layer formed on weathering steel is mainly α-FeOOH. (author)

Genome-wide association mapping for stripe rust (Puccinia striiformis F. sp. tritici) in US Pacific Northwest winter wheat (Triticum aestivum L.).

Science.gov (United States)

Naruoka, Y; Garland-Campbell, K A; Carter, A H

2015-06-01

Potential novel and known QTL for race-specific all-stage and adult plant resistance to stripe rust were identified by genome-wide association mapping in the US PNW winter wheat accessions. Stripe rust (Puccinia striiformis F. sp. tritici; also known as yellow rust) is a globally devastating disease of wheat (Triticum aestivum L.) and a major threat to wheat production in the US Pacific Northwest (PNW), therefore both adult plant and all-stage resistance have been introduced into the winter wheat breeding programs in the PNW. The goal of this study was to identify quantitative trait loci (QTL) and molecular markers for these resistances through genome-wide association (GWAS) mapping in winter wheat accessions adapted to the PNW. Stripe rust response for adult plants was evaluated in naturally occurring epidemics in a total of nine environments in Washington State, USA. Seedling response was evaluated with three races under artificial inoculation in the greenhouse. The panel was genotyped with the 9K Illumina Wheat single nucleotide polymorphism (SNP) array and additional markers linked to previously reported genes and QTL for stripe rust resistance. The population was grouped into three sub-populations. Markers linked to Yr17 and previously reported QTL for stripe rust resistance were identified on chromosomes 1B, 2A, and 2B. Potentially novel QTL associated with race-specific seedling response were identified on chromosomes 1B and 1D. Potentially novel QTL associated with adult plant response were located on chromosomes 2A, 2B, 3B, 4A, and 4B. Stripe rust was reduced when multiple alleles for resistance were present. The resistant allele frequencies were different among sub-populations in the panel. This information provides breeders with germplasm and closely linked markers for stripe rust resistance to facilitate the transfer of multiple loci for durable stripe rust resistance into wheat breeding lines and cultivars.

Differential resistance to stripe rust (Puccinia striiformis) in collections of basin wild rye (Leymus cinereus)

Science.gov (United States)

Frank M. Dugan; Michael J. Cashman; Richard C. Johnson; Meinan Wang; Chen Xianming

2014-01-01

Differential resistance to stripe rust (Puccinia striiformis) in a planting of 111 wild collections of Basin wild rye (Leymus cinereus) was noted 2011-2013. In 2011, rust severity was rated on a scale of 1-9. Much lighter infection in 2012 and 2013 was rated as the number of symptomatic leaves per plant divided by plant circumference (to adjust for plant size). Effect...

Protective, curative and eradicative activities of fungicides against grapevine rust

Directory of Open Access Journals (Sweden)

Francislene Angelotti

2014-01-01

Full Text Available The protective, eradicative and curative activities of the fungicides azoxystrobin, tebuconazole, pyraclostrobin+metiram, and ciproconazole against grapevine rust, were determined in greenhouse. To evaluate the protective activity, leaves of potted ´Niagara´ (Vitis labrusca vines were artificially inoculated with an urediniospore suspension of Phakopsora euvitis four, eight or forteen days after fungicidal spray; and to evaluate the curative and eradicative activities, leaves were sprayed with fungicides two, four or eight days after inoculation. Disease severity was assessed 14 days after each inoculation. All tested fungicides present excellent preventive activity against grapevine rust; however, tebuconazole and ciproconazole provide better curative activity than azoxystrobin and pyraclostrobin+metiram. It was observed also that all tested fungicides significantly reduced the germination of urediniospore produced on sprayed leaves.

Morphology of germlings of urediniospores and its value for the identification and classification of grass rust fungi

NARCIS (Netherlands)

Swertz, C.A.

1994-01-01

The identification and classification of grass rust fungi is often difficult since most traditionally used morphological characters are quantitative and subjective. Besides, when using the host range as a taxonomic criterion, it is important to realize that a rust fungus may have jumped to

A coupled carbonation-rust formation mechanical damage model for steel corrosion in reinforced concrete

International Nuclear Information System (INIS)

Nguyen, Huyen; Bary, B.; L'Hostis, Valerie; DeLarrard, T.

2014-01-01

This paper aims at presenting a strategy to simulate the corrosion of steel reinforcement due to carbonation of concrete in atmospheric environment. We propose a model coupling drying, carbonation, diffusion of oxygen, formation of rust and mechanics to describe these phenomena. The rust layer is assumed to be composed of two sub-layers with different elastic modulus. An unstable layer with a low modulus (from 0.1 to 5 GPa) is located next to the transformed medium, and another more stable one with a higher modulus (from 100 to 150 GPa) at the interface with steel reinforcement. This model is applied to a numerical meso-structure composed of 4 phases: mortar matrix, randomly distributed aggregates, steel rebar and rust layers to underline the effect of aggregates on damage initiation and corresponding crack pattern of concrete cover. (authors)

Identifying Quantitative Trait Loci (QTLs) and Developing Diagnostic Markers Linked to Orange Rust Resistance in Sugarcane (Saccharum spp.).

Science.gov (United States)

Yang, Xiping; Islam, Md S; Sood, Sushma; Maya, Stephanie; Hanson, Erik A; Comstock, Jack; Wang, Jianping

2018-01-01

Sugarcane ( Saccharum spp.) is an important economic crop, contributing up to 80% of table sugar used in the world and has become a promising feedstock for biofuel production. Sugarcane production has been threatened by many diseases, and fungicide applications for disease control have been opted out for sustainable agriculture. Orange rust is one of the major diseases impacting sugarcane production worldwide. Identifying quantitative trait loci (QTLs) and developing diagnostic markers are valuable for breeding programs to expedite release of superior sugarcane cultivars for disease control. In this study, an F 1 segregating population derived from a cross between two hybrid sugarcane clones, CP95-1039 and CP88-1762, was evaluated for orange rust resistance in replicated trails. Three QTLs controlling orange rust resistance in sugarcane (qORR109, qORR4 and qORR102) were identified for the first time ever, which can explain 58, 12 and 8% of the phenotypic variation, separately. We also characterized 1,574 sugarcane putative resistance ( R ) genes. These sugarcane putative R genes and simple sequence repeats in the QTL intervals were further used to develop diagnostic markers for marker-assisted selection of orange rust resistance. A PCR-based Resistance gene-derived maker, G1 was developed, which showed significant association with orange rust resistance. The putative QTLs and marker developed in this study can be effectively utilized in sugarcane breeding programs to facilitate the selection process, thus contributing to the sustainable agriculture for orange rust disease control.

Characterisation of rust surfaces formed on mild steel exposed to marine atmospheres using XRD and SEM/Micro-Raman techniques

International Nuclear Information System (INIS)

Fuente, D. de la; Alcántara, J.; Chico, B.; Díaz, I.; Jiménez, J.A.; Morcillo, M.

2016-01-01

Highlights: • SEM/Micro-Raman is very useful for characterizing rust phases morphologies. • SEM/Micro-Raman enables unequivocal rust phases identification. • γ-FeOOH basically presents two types of morphologies: globular and laminar. • Fe 3 O 4 presents two morphologies: flat patches and black doughnut-type formations. • β-FeOOH presents highly porous morphologies comprised by fine prismatic crystals. - Abstract: The exposure of mild steel to marine atmospheres gives rise to the formation of various corrosion products, mainly lepidocrocite, goethite, magnetite and akaganeite. In this study, Grazing Incidence X-Ray Diffraction, Micro-X-Ray Diffraction and Scanning Electron Microscopy/Micro-Raman are used to characterise rust layer surfaces and to identify the principal component rust phases and their morphology. The main conclusion reached is that lepidocrocite is preferentially located on the outermost surface while magnetite and akaganeite form mostly close to base steel. The Scanning Electron Microscopy/Micro-Raman technique has been very useful for characterising (identifying) the wide variety of morphologies presented by the rust phases.

Anaerobic co-culture of mesenchymal stem cells and anaerobic pathogens - a new in vitro model system.

Directory of Open Access Journals (Sweden)

Katja Kriebel

Full Text Available BACKGROUND: Human mesenchymal stem cells (hMSCs are multipotent by nature and are originally isolated from bone marrow. In light of a future application of hMSCs in the oral cavity, a body compartment with varying oxygen partial pressures and an omnipresence of different bacterial species i.e. periodontitis pathogens, we performed this study to gain information about the behavior of hMSC in an anaerobic system and the response in interaction with oral bacterial pathogens. METHODOLOGY/PRINCIPAL FINDINGS: We established a model system with oral pathogenic bacterial species and eukaryotic cells cultured in anaerobic conditions. The facultative anaerobe bacteria Fusobacterium nucleatum, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans were studied. Their effects on hMSCs and primary as well as permanent gingival epithelial cells (Ca9-22, HGPEC were comparatively analyzed. We show that hMSCs cope with anoxic conditions, since 40% vital cells remain after 72 h of anaerobic culture. The Ca9-22 and HGPEC cells are significantly more sensitive to lack of oxygen. All bacterial species reveal a comparatively low adherence to and internalization into hMSCs (0.2% and 0.01% of the initial inoculum, respectively. In comparison, the Ca9-22 and HGPEC cells present better targets for bacterial adherence and internalization. The production of the pro-inflammatory chemokine IL-8 is higher in both gingival epithelial cell lines compared to hMSCs and Fusobacterium nucleatum induce a time-dependent cytokine secretion in both cell lines. Porphyromonas gingivalis is less effective in stimulating secretion of IL-8 in the co-cultivation experiments. CONCLUSIONS/SIGNIFICANCE: HMSCs are suitable for use in anoxic regions of the oral cavity. The interaction with local pathogenic bacteria does not result in massive pro-inflammatory cytokine responses. The test system established in this study allowed further investigation of parameters prior to set up of

Comparative Analysis Highlights Variable Genome Content of Wheat Rusts and Divergence of the Mating Loci

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Christina A. Cuomo

2017-02-01

Full Text Available Three members of the Puccinia genus, Puccinia triticina (Pt, P. striiformis f.sp. tritici (Pst, and P. graminis f.sp. tritici (Pgt, cause the most common and often most significant foliar diseases of wheat. While similar in biology and life cycle, each species is uniquely adapted and specialized. The genomes of Pt and Pst were sequenced and compared to that of Pgt to identify common and distinguishing gene content, to determine gene variation among wheat rust pathogens, other rust fungi, and basidiomycetes, and to identify genes of significance for infection. Pt had the largest genome of the three, estimated at 135 Mb with expansion due to mobile elements and repeats encompassing 50.9% of contig bases; in comparison, repeats occupy 31.5% for Pst and 36.5% for Pgt. We find all three genomes are highly heterozygous, with Pst [5.97 single nucleotide polymorphisms (SNPs/kb] nearly twice the level detected in Pt (2.57 SNPs/kb and that previously reported for Pgt. Of 1358 predicted effectors in Pt, 784 were found expressed across diverse life cycle stages including the sexual stage. Comparison to related fungi highlighted the expansion of gene families involved in transcriptional regulation and nucleotide binding, protein modification, and carbohydrate degradation enzymes. Two allelic homeodomain pairs, HD1 and HD2, were identified in each dikaryotic Puccinia species along with three pheromone receptor (STE3 mating-type genes, two of which are likely representing allelic specificities. The HD proteins were active in a heterologous Ustilago maydis mating assay and host-induced gene silencing (HIGS of the HD and STE3 alleles reduced wheat host infection.

75 FR 53861 - Airworthiness Directives; Robert E. Rust, Jr. Model DeHavilland DH.C1 Chipmunk 21, DH.C1 Chipmunk...

Science.gov (United States)

2010-09-02

... Airworthiness Directives; Robert E. Rust, Jr. Model DeHavilland DH.C1 Chipmunk 21, DH.C1 Chipmunk 22, and DH.C1...). ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for all Robert E. Rust... CFR part 39) to include an AD that would apply to all Robert E. Rust, Jr. Models DeHavilland DH.C1...

Synthesis and New Observations on Needle Pathogens of Larch in Northern Finland

Directory of Open Access Journals (Sweden)

Risto Jalkanen

2016-01-01

Full Text Available Needle pathogens of larch (Larix spp. in the Nordic countries are under-studied. Their incidence in Finland tends to be low and local, and this may be a function of enemy release, since species of larch were introduced to the region. Here, the ecology and incidence of larch needle pathogens and the abiotic factors that also affect larch in northern Finland are reviewed. Field observations and related laboratory analyses during the past 35 years have mainly been obtained near the Kivalo Research Area within the Arctic Circle, Finnish Lapland. The relatively recent introduction of Hypodermella laricis is a primary focus. This pathogen is not only new to Nordic countries, but can cause severe outbreaks, defoliation and crown-thinning in the canopies of all ages of most planted larch species worldwide. Symptoms of H. laricis clearly differ from those of Mycosphaerella laricina; the latter has affected Larix sibirica at high latitudes for decades. The effects of Meria laricis, Lophodermium laricinum, various rust fungi, and wind and frost are also discussed.

Helen Hart, remarkable plant pathologist (1900-1971).

Science.gov (United States)

Wilcoxson, R D

1996-01-01

Helen Hart was a Professor of Plant Pathology at the University of Minnesota from 1924 until retirement in 1966. Born in Janeville, Wisconsin, she died at Grants Pass, Oregon. Her scholarly research concentrated on wheat stem rust to understand host pathogen relationships and to develop rust-resistant cultivars. She did not teach formal courses but was heavily involved in making seminars a vital part of instruction, in teaching languages needed for graduate studies, and as an informal advisor for most rust research theses. She had common sense, excellent scientific judgment, and sound instincts on personnel matters that served the department well. A talented science writer, Hart served as editor of hundreds of theses and departmental manuscripts for publication. Her writing and editing skills were used as associate editor of Phytopathology for two years and as editor-in-chief from 1944-1951. A strong advocate of The American Phytopathological Society, Helen Hart served on Council for 12 years and as President in 1956. Helen Hart was a great professional scientist who had a far-reaching impact on plant pathology during the twentieth century.

Prescreening slash pine and Cronartium pedigrees for evaluation of complementary gene action in fusiform rust disease.

Science.gov (United States)

H.E. Stelzer; Robert L. Doudrick; Thomas L. Kubisiak; C. Dana Nelson

1999-01-01

Single-urediniospore cultures of the fusiform rust fungus were used to inoculate seedlings from 10 full-sib families of a five-parent slash pine diallel at two different times in 1994. The presence or absence of fusiform rust galls was recorded for each inoculated seedling at 9 months postinoculation, and percent infection levels for each family-inoculum-time...

Screening of fungicides for the management of wattle rust ...

African Journals Online (AJOL)

% of the revenue from the species obtained from the timber and 15% from the bark. From 2012/13 a wattle rust disease has spread throughout the black wattle plantation area in KwaZulu-Natal and from 2015 it was recorded in southern ...

Distribution and frequency of Bru1, a major brown rust resistance gene, in the sugarcane world collection

Science.gov (United States)

Brown rust, caused by Puccinia melanocephala, is an important disease of sugarcane worldwide. Molecular markers for a major brown rust resistance gene, Bru1, were used to screen a total of 1,282 clones in the World Collection of Sugarcane and Related Grasses (WCSRG) to determine the distribution and...

Marker-assisted pyramiding of Thinopyrum-derived leaf rust ...

Indian Academy of Sciences (India)

Annual Meetings · Mid Year Meetings · Discussion Meetings · Public Lectures · Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Journal of Genetics; Volume 96; Issue 6. Marker-assisted pyramiding of Thinopyrum-derived leaf rust resistance genes Lr19 and Lr24 in bread wheat variety ...

Mapping and characterization of the new adult plant leaf rust resistance gene Lr77 derived from Santa Fe winter wheat.

Science.gov (United States)

Kolmer, James A; Su, Zhenqi; Bernardo, Amy; Bai, Guihua; Chao, Shiaoman

2018-04-25

A new gene for adult plant leaf rust resistance in wheat was mapped to chromosome 3BL. This gene was designated as Lr77. 'Santa Fe' is a hard red winter cultivar that has had long-lasting resistance to the leaf rust fungus, Puccinia triticina. The objective of this study was to determine the chromosome location of the adult plant leaf rust resistance in Santa Fe wheat. A partial backcross line of 'Thatcher' (Tc) wheat with adult plant leaf rust resistance derived from Santa Fe was crossed with Thatcher to develop a Thatcher//Tc*2/Santa Fe F 6 recombinant inbred line (RIL) population. The RIL population and parental lines were evaluated for segregation of leaf rust resistance in three field plot tests and in an adult plant greenhouse test. A genetic map of the RIL population was constructed using 90,000 single-nucleotide polymorphism (SNP) markers with the Illumina Infinium iSelect 90K wheat bead array. A significant quantitative trait locus for reduction of leaf rust severity in all four tests was found on chromosome 3BL that segregated as a single adult plant resistance gene. The RILs with the allele from the resistant parent for SNP marker IWB10344 had lower leaf rust severity and a moderately resistant to moderately susceptible response compared to the susceptible RILs and Thatcher. The gene derived from Santa Fe on chromosome 3BL was designated as Lr77. Kompetitive allele-specific polymerase chain reaction assay markers linked to Lr77 on 3BL should be useful for selection of wheat germplasm with this gene.

X-ray diffraction analysis of rust layer on a weathering steel bridge with surface treatment using synchrotron radiation

International Nuclear Information System (INIS)

Yamashita, Masato; Hara, Shuichi; Kamimura, Takayuki; Miyuki, Hideaki; Sato, Masugu

2007-01-01

We have examined the structure of rust layer formed on a weathering steel bridge, to which the surface treatment, employing the effect of Cr 2 (SO 4 ) 3 sophisticatedly designed to form the protective goethite (α-FeOOH) rust layer which contains a certain amount of Cr, Cr-goethite, was applied in 1996, using X-ray diffraction at SPring-8 synchrotron radiation facility. It was shown that the formation of α-FeOOH was promoted and/or crystal growth of γ-FeOOH was suppressed by the surface treatment. The increase in the protective ability index (PAI) of the rust layer indicates that the protective goethite was predominantly formed under the effect of the surface treatment. In conclusion, it can be said that the surface treatment worked well to promote the formation of the protective goethite rust layer on the weathering steel bridge during the 10-year exposure. (author)

Induced resistance and gene expression in wheat against leaf rust ...

African Journals Online (AJOL)

uvp

2013-05-15

May 15, 2013 ... 2Department of Soil, Crop and Climate Sciences, University of the Free State, P.O Box ... Key words: Wheat leaf rust, induced resistance, priming, gene ..... transformation: susceptibility of transgenic Nicotiana sylvestris plants.

Flavonoid Accumulation Plays an Important Role in the Rust Resistance of Malus Plant Leaves

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Yanfen Lu

2017-07-01

Full Text Available Cedar-apple rust (Gymnosporangium yamadai Miyabe is a fungal disease that causes substantial injury to apple trees and results in fruit with reduced size and quality and a lower commercial value. The molecular mechanisms underlying the primary and secondary metabolic effects of rust spots on the leaves of Malus apple cultivars are poorly understood. Using HPLC, we found that the contents of flavonoid compounds, especially anthocyanin and catechin, were significantly increased in rust-infected symptomatic tissue (RIT. The expression levels of structural genes and MYB transcription factors related to flavonoid biosynthesis were one- to seven-fold higher in the RIT. Among these genes, CHS, DFR, ANS, FLS and MYB10 showed more than a 10-fold increase, suggesting that these genes were expressed at significantly higher levels in the RIT. Hormone concentration assays showed that the levels of abscisic acid (ABA, ethylene (ETH, jasmonate (JA and salicylic acid (SA were higher in the RIT and were consistent with the expression levels of McNCED, McACS, McLOX and McNPR1, respectively. Our study explored the complicated crosstalk of the signal transduction pathways of ABA, ETH, JA and SA; the primary metabolism of glucose, sucrose, fructose and sorbitol; and the secondary metabolism of flavonoids involved in the rust resistance of Malus crabapple leaves.

Mapping of stripe rust resistance gene in an Aegilops caudata ...

Indian Academy of Sciences (India)

Seedling resistance is usually race-specific, but often pro- vides complete ... Genomic DNA was extracted using the CTAB method of. Saghai-Maroof ... Polymerase chain reactions (PCR) were performed in ..... The continuous supply of the rust ...

Use of AFLP marker system on sugarcane somaclones to study their resistance to rust

OpenAIRE

María Ileana Oloriz; Luis Rojas; Víctor Gil; Milady Mendoza; Ariel Arencibia; Elva Rosa Carmona; Elio Jiménez

2002-01-01

AFLPs (amplified fragment length polymorphism) was carried out from genomic DNA of five rust resistant sugar cane somaclons and their susceptible donor, Saccharum officinarum var B 4362, using three combinations of primers (EcoRI/aca: MseI/acc; EcoRI/aca: MseI/atg and EcoRI/aca: MseI/agg). Six polymorphic bands were obtained, two of these only appeared in the resistant genotypes, which are probably DNA sequences, related to rust resistance locus. These fragments have been cloned to study thei...

Avoiding the Use of Exhausted Drinking Water Filters: A Filter-Clock Based on Rusting Iron

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Arnaud Igor Ndé-Tchoupé

2018-05-01

Full Text Available Efficient but affordable water treatment technologies are currently sought to solve the prevalent shortage of safe drinking water. Adsorption-based technologies are in the front-line of these efforts. Upon proper design, universally applied materials (e.g., activated carbons, bone chars, metal oxides are able to quantitatively remove inorganic and organic pollutants as well as pathogens from water. Each water filter has a defined removal capacity and must be replaced when this capacity is exhausted. Operational experience has shown that it may be difficult to convince some low-skilled users to buy new filters after a predicted service life. This communication describes the quest to develop a filter-clock to encourage all users to change their filters after the designed service life. A brief discussion on such a filter-clock based on rusting of metallic iron (Fe0 is presented. Integrating such filter-clocks in the design of water filters is regarded as essential for safeguarding public health.

Selection and evaluation of soybean lines derived from gamma irradiation for rust resistance

International Nuclear Information System (INIS)

Smutkupt, S.; Wongpiyasatid, A.; Lamseejan, S.

1983-01-01

In 1979, seeds of 11 soybean cultivars were gamma irradiated with 15 and 30 krad. Treated and control seeds of each cultivar were planted in the rainy season. In the rainy season of 1980, M 3 populations were screened for rust resistance in Nong Hoi Valley and Mae Joe Experiment Station, both in Chiang Main province. The IWGSR rust rating system was used. Based upon the slow growth of rust on soybean plants, 6 and 115 plants were selected from 2,802 control plants and from 28,824 treated plants, respectively. Selected lines were evaluated in Nong Hoi Valley in the rainy season of 1981. Sixteen selections with average good seed yield per plant and low percentage of shrivelled seeds were obtained. Among them, two lines, namely G8586/Line number 81-1-072 and S.J. 4/Line number 81-1-037 gave the higher average seed yield per plant than other lines. They are at present in a preliminary yield trial in Chiang Mai. Chiang Mai. (author)

Resistance of some early mutant lines of soybean to rust fungus (Phakospora pachyrhizi Syd)

International Nuclear Information System (INIS)

Ratma, Rivaie

1984-01-01

A trial for resistance to rust fungus (Phakospora pachyrhizi Syd.) was conducted on 11 early mutant lines of soybean M6 (derived from Orba variety with a dose of 0.4 kGy of Co-60) at Citayam Experimental Station, Bogor, in the wet season of 80/81. Based on IWGSR rating system, soybean mutant lines number M6/40/6 was moderately susceptible to rust fungus (Phakospora pachyrhizi Syd). While 10 other soybean mutant lines M6/40/1, M6/40/2, M6/40/3, M6/40/4, M6/40/5, M6/40/7, M6/40/8, M6/40/9, M6/40/10 and M6/40/11 were susceptible to rust fungus. Significant differences in yield were observed between the early mutant lines M6/40/6 (moderate susceptible), 10 other mutant lines (susceptible) and ringgit variety (susceptible). However, a significant lower yield was produced by those mutant lines compared with the yield of orba variety. (author)

Induced mutations for tolerance of oats to crown rust

International Nuclear Information System (INIS)

Simons, M.D.; Frey, K.J.

1977-01-01

Seeds of three oat (Avena sativa and A. abyssinica) strains were treated with ethyl methanesulphonate (EMS), and crown rust (caused by Puccinia coronata var. avenae) tolerance ratios of M 5 -derived lines were compared with untreated checks. Tolerance ratios of mutant lines tended to be distributed in both plus and minus directions. No mutant oat line had a significant increase in grain yield, but many showed significantly depressed yields. With C.I. 6665, only five of 130 mutagen-derived lines were not significantly below the check for grain yield; one of these had significantly improved tolerance. Re-treatment of selected strains from a previous EMS treatment (original cultivar was Clintland-60) gave one M 5 -derived oat line (of 100 tested) that was equal to Clintland-60 in grain yield and sustained no damage from crown rust (i.e. it had a tolerance ratio of 100). EMS treatment of the highly susceptible tetraploid C.I. 2110 resulted in both significantly increased and reduced tolerance. (author)

Evaluation of sugarcane introgression lines for resistance to brown rust disease caused by Puccinia melanocephala

OpenAIRE

Wang, Xiao-Yan; Wen-Feng, Li; Ying-Kun, Huang; Xin, Lu; Zhi-Ming, Luo; Jiong, Yin; Hong-Li, Shan; Rong-Yue, Zhang

2013-01-01

Sugarcane brown rust disease caused by Puccinia melanocephala is one of the important fungal diseases affecting sugarcane yield around the world. Cultivar resistance is the most appropriate control method for this disease. In this study, 62 introgression lines chosen from the crossing Saccharum officinarum L. cv. Ludashi x Erianthus rockii Yunnan 95-19 were evaluated for brown rust resistance using artificial inoculation. More than 30% of the introgression lines were identified as resistant. ...

Amplified fragment length polymorphism of Puccinia graminis f. sp ...

African Journals Online (AJOL)

The developed AFLP fingerprints for the Ethiopian Pgt isolates reported herein could support the breeding program to develop strategies for the deployment of resistance genes in its continued effort to minimize the impact of stem rust on wheat in Ethiopia. Keywords: AFLP, wheat, stem rust, genetic diversity, population ...

Characterization of rust layer formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich environment by Cl and Fe K-edge XANES measurements

International Nuclear Information System (INIS)

Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

2005-01-01

Chloride in atmosphere considerably reduces the corrosion resistance of conventional weathering steel containing a small amount of Cr. Ni is an effective anticorrosive element for improving the corrosion resistance of steel in a Cl-rich environment. In order to clarify the structure of the protective rust layer of weathering steel, Cl and Fe K-edge X-ray absorption near edge structure (XANES) spectra of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich atmosphere were measured. The Fe K-XANES measurements enable the characterization of mixture of iron oxides such as rust. The chemical composition of the rust was determined by performing pattern fitting of the measured spectra. All the rust is composed mainly of goethite, akaganeite, lepidocrocite and magnetite. Among these iron oxides, akaganeite in particular is the major component in the rust. Additionally, the amount of akaganeite in the rust of Fe-Ni alloy is much greater than that in rust of Fe-Cr alloy. Akaganeite is generally considered to facilitate the corrosion of steel, but our results indicate that akaganeite in the rust of Fe-Ni alloy is quantitatively different from that in rust of Fe-Cr alloy and does not facilitate the corrosion of steel. The shoulder peak observed in Cl K-XANES spectra reveals that the rust contains a chloride other than akaganeite. The energy of the shoulder peak does not correspond to that of any well-known chlorides. In the measured spectra, there is no proof that Cl, by combining with the alloying element, inhibits the alloying element from acting in corrosion resistance. The shoulder peak appears only when the content of the alloying element is lower than a certain value. This suggests that the generation of the unidentified chloride is related to the corrosion rate of steel. (author)

The Emerging British Verticillium longisporum Population Consists of Aggressive Brassica Pathogens.

Science.gov (United States)

Depotter, Jasper R L; Rodriguez-Moreno, Luis; Thomma, Bart P H J; Wood, Thomas A

2017-11-01

Verticillium longisporum is an economically important fungal pathogen of brassicaceous crops that originated from at least three hybridization events between different Verticillium spp., leading to the hybrid lineages A1/D1, A1/D2, and A1/D3. Isolates of lineage A1/D1 generally cause stem striping on oilseed rape (Brassica napus), which has recently been reported for the first time to occur in the United Kingdom. Intriguingly, the emerging U.K. population is distinct from the north-central European stem striping population. Little is known about the pathogenicity of the newly emerged U.K. population; hence, pathogenicity tests were executed to compare British isolates to previously characterized reference strains. In addition to the model plant Arabidopsis thaliana, the pathogenicity of four British isolates was assessed on four cultivars of three Brassica crop species: oilseed rape (Quartz and Incentive), cauliflower (Clapton), and Chinese cabbage (Hilton). To this end, vascular discoloration of the roots, plant biomass accumulations, and fungal stem colonization upon isolate infection were evaluated. The British isolates appeared to be remarkably aggressive, because plant biomass was significantly affected and severe vascular discoloration was observed. The British isolates were successful stem colonizers and the extent of fungal colonization negatively correlated with plant biomass of cauliflower and Quartz oilseed rape. However, in Quartz, the fungal colonization of A1/D1 isolates was significantly lower than that of the virulent reference isolate from lineage A1/D3, PD589. Moreover, despite levels of stem colonization similar to those of A1/D1 strains, PD589 did not cause significant disease on Incentive. Thus, A1/D1 isolates, including British isolates, are aggressive oilseed rape pathogens despite limited colonization levels in comparison with a virulent A1/D3 isolate.

Adult plant leaf rust resistance derived from Toropi wheat is conditioned by Lr78 and three minor QTL

Science.gov (United States)

Brazil, was noted to have long lasting leaf rust resistance that was effective only in adult plants. The objectives of this study were to determine the chromosome location of the leaf rust resistance genes derived from Toropi in two populations of recombinant inbred lines in a partial Thatcher wheat...

White pine blister rust in Korea, Japan and other Asian regions: comparisons and implications for North America

Science.gov (United States)

M.-S. Kim; N. B. Klopfenstein; Y. Ota; S. K. Lee; K.-S. Woo; S. Kaneko

2010-01-01

This article briefly reviews the history of white pine blister rust, attributed to Cronartium ribicola, and addresses current research and management issues in South Korea, Japan and other regions of eastern Asia (China, Russia and Himalaya). For each region, the distribution, damage, aecial hosts, telial hosts and management of C. ribicola and other blister rust fungi...

Relative Fusiform Rust Resistance of Loblolly and Slash Pine Sources and Families in Georgia and South Carolina

Science.gov (United States)

E. George Kuhlman; Harry R. Powers; William D. Pepper

1995-01-01

Loblolly and slash pine seedlings from the fusiform rust resistant orchards developed cooperatively by the USDA Forest Service and the Georgia Forestry Commission had significantly less rust 7 to 8 years after planting on four of five sites in the Southeastern United States than seedlings of the same species from orchard sources developed primarily for silvicultural...

Tracking the distribution of Puccinia psidii genotypes that cause rust disease on diverse myrtaceous trees and shrubs

Science.gov (United States)

Amy L. Ross-Davis; Rodrigo N. Graca; Acelino C. Alfenas; Tobin L. Peever; Jack W. Hanna; Janice Y. Uchida; Rob D. Hauff; Chris Y. Kadooka; Mee-Sook Kim; Phil G. Cannon; Shigetou Namba; Nami Minato; Sofia Simeto; Carlos A. Perez; Min B. Rayamajhi; Mauricio Moran; D. Jean Lodge; Marcela Arguedas; Rosario Medel-Ortiz; M. Armando Lopez-Ramirez; Paula Tennant; Morag Glen; Ned B. Klopfenstein

2014-01-01

Puccinia psidii Winter (Basidiomycota, Uredinales) is a biotrophic rust fungus that was first reported in Brazil from guava in 1884 (Psidium guajava; Winter 1884) and later from eucalypt in 1912 (Joffily 1944). Considered to be of neotropical origin, the rust has also been reported to infect diverse myrtaceous hosts elsewhere in South America, Central America, the...

QTL-seq approach identified genomic regions and diagnostic markers for rust and late leaf spot resistance in groundnut (Arachis hypogaea L.).

Science.gov (United States)

Pandey, Manish K; Khan, Aamir W; Singh, Vikas K; Vishwakarma, Manish K; Shasidhar, Yaduru; Kumar, Vinay; Garg, Vanika; Bhat, Ramesh S; Chitikineni, Annapurna; Janila, Pasupuleti; Guo, Baozhu; Varshney, Rajeev K

2017-08-01

Rust and late leaf spot (LLS) are the two major foliar fungal diseases in groundnut, and their co-occurrence leads to significant yield loss in addition to the deterioration of fodder quality. To identify candidate genomic regions controlling resistance to rust and LLS, whole-genome resequencing (WGRS)-based approach referred as 'QTL-seq' was deployed. A total of 231.67 Gb raw and 192.10 Gb of clean sequence data were generated through WGRS of resistant parent and the resistant and susceptible bulks for rust and LLS. Sequence analysis of bulks for rust and LLS with reference-guided resistant parent assembly identified 3136 single-nucleotide polymorphisms (SNPs) for rust and 66 SNPs for LLS with the read depth of ≥7 in the identified genomic region on pseudomolecule A03. Detailed analysis identified 30 nonsynonymous SNPs affecting 25 candidate genes for rust resistance, while 14 intronic and three synonymous SNPs affecting nine candidate genes for LLS resistance. Subsequently, allele-specific diagnostic markers were identified for three SNPs for rust resistance and one SNP for LLS resistance. Genotyping of one RIL population (TAG 24 × GPBD 4) with these four diagnostic markers revealed higher phenotypic variation for these two diseases. These results suggest usefulness of QTL-seq approach in precise and rapid identification of candidate genomic regions and development of diagnostic markers for breeding applications. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Frequency and distribution of the brown rust resistance gene Bru1 and implications for the Louisiana sugarcane breeding programme

Science.gov (United States)

Brown rust, caused by the fungus Puccinia melanocephala, is an important disease of sugarcane posing an increasing threat to sugarcane industries worldwide. A major gene, Bru1, has been shown to contribute a significant proportion of brown rust resistance in multiple sugarcane industries. The recent...

Synthesis and characterisation of the Fe(II-III) hydroxy-formate green rust

International Nuclear Information System (INIS)

Refait, P.; Abdelmoula, M.; Genin, J.-M. R.; Jeannin, M.

2006-01-01

A new methodology was envisioned in order to prepare green rust compounds build on organic anions that could intervene in microbiologically influenced corrosion processes of iron and steel. The formate ion was chosen as an example. The formation of rust was simulated by the oxidation of aqueous suspensions of Fe(OH) 2 precipitated from Fe(II) lactate and sodium hydroxide, in the presence of sodium formate to promote the formation of the corresponding green rust. The evolution of the precipitate with time was followed by transmission Moessbauer spectroscopy at 15 K. It was observed that the initial hydroxide was transformed into a new GR compound. Its spectrum is composed of three quadrupole doublets, D 1 (δ = 1.28 mm s -1 , Δ = 2.75 mm s -1 ) and D 2 (δ = 1.28 mm s -1 , Δ 2.48 mm s -1 ) that correspond to Fe(II) and D 3 (δ = 0.49 mm s -1 , Δ = 0.37 mm s -1 ) that corresponds to Fe(III). The relative area of D 3 , close to the proportion of Fe(III) in the GR, was found at 28.5 ± 1.5% (∼2/7). Raman spectroscopy confirmed that the intermediate compound was a Fe(II-III) hydroxy-formate, GR(HCOO - ).

Influence of stripe rust infection on the photosynthetic characteristics and antioxidant system of susceptible and resistant wheat cultivars at the adult plant stage.

Science.gov (United States)

Chen, Yang-Er; Cui, Jun-Mei; Su, Yan-Qiu; Yuan, Shu; Yuan, Ming; Zhang, Huai-Yu

2015-01-01

Wheat stripe rust (Puccinia striiformis f. sp. tritici, Pst), is one of the most serious diseases of wheat (Triticum aestivum L.) worldwide. To gain a better understanding of the protective mechanism against stripe rust at the adult plant stage, the differences in photosystem II and antioxidant enzymatic systems between susceptible and resistant wheat in response to stripe rust disease (P. striiformis) were investigated. We found that chlorophyll fluorescence and the activities of the antioxidant enzymes were higher in resistant wheat than in susceptible wheat after stripe rust infection. Compared with the susceptible wheat, the resistant wheat accumulated a higher level of D1 protein and a lower level of reactive oxygen species after infection. Furthermore, our results demonstrate that D1 and light-harvesting complex II (LHCII) phosphorylation are involved in the resistance to stripe rust in wheat. The CP29 protein was phosphorylated under stripe rust infection, like its phosphorylation in other monocots under environmental stresses. More extensive damages occur on the thylakoid membranes in the susceptible wheat compared with the resistant wheat. The findings provide evidence that thylakoid protein phosphorylation and antioxidant enzyme systems play important roles in plant responses and defense to biotic stress.

Quantitative trait loci for resistance to stripe rust of wheat revealed using global field nurseries and opportunities for stacking resistance genes.

Science.gov (United States)

Bokore, Firdissa E; Cuthbert, Richard D; Knox, Ron E; Randhawa, Harpinder S; Hiebert, Colin W; DePauw, Ron M; Singh, Asheesh K; Singh, Arti; Sharpe, Andrew G; N'Diaye, Amidou; Pozniak, Curtis J; McCartney, Curt; Ruan, Yuefeng; Berraies, Samia; Meyer, Brad; Munro, Catherine; Hay, Andy; Ammar, Karim; Huerta-Espino, Julio; Bhavani, Sridhar

2017-12-01

Quantitative trait loci controlling stripe rust resistance were identified in adapted Canadian spring wheat cultivars providing opportunity for breeders to stack loci using marker-assisted breeding. Stripe rust or yellow rust, caused by Puccinia striiformis Westend. f. sp. tritici Erikss., is a devastating disease of common wheat (Triticum aestivum L.) in many regions of the world. The objectives of this research were to identify and map quantitative trait loci (QTL) associated with stripe rust resistance in adapted Canadian spring wheat cultivars that are effective globally, and investigate opportunities for stacking resistance. Doubled haploid (DH) populations from the crosses Vesper/Lillian, Vesper/Stettler, Carberry/Vesper, Stettler/Red Fife and Carberry/AC Cadillac were phenotyped for stripe rust severity and infection response in field nurseries in Canada (Lethbridge and Swift Current), New Zealand (Lincoln), Mexico (Toluca) and Kenya (Njoro), and genotyped with SNP markers. Six QTL for stripe rust resistance in the population of Vesper/Lillian, five in Vesper/Stettler, seven in Stettler/Red Fife, four in Carberry/Vesper and nine in Carberry/AC Cadillac were identified. Lillian contributed stripe rust resistance QTL on chromosomes 4B, 5A, 6B and 7D, AC Cadillac on 2A, 2B, 3B and 5B, Carberry on 1A, 1B, 4A, 4B, 7A and 7D, Stettler on 1A, 2A, 3D, 4A, 5B and 6A, Red Fife on 2D, 3B and 4B, and Vesper on 1B, 2B and 7A. QTL on 1A, 1B, 2A, 2B, 3B, 4A, 4B, 5B, 7A and 7D were observed in multiple parents. The populations are compelling sources of recombination of many stripe rust resistance QTL for stacking disease resistance. Gene pyramiding should be possible with little chance of linkage drag of detrimental genes as the source parents were mostly adapted cultivars widely grown in Canada.

Haplotype structure around Bru1 reveals a narrow genetic basis for brown rust resistance in modern sugarcane cultivars.

Science.gov (United States)

Costet, L; Le Cunff, L; Royaert, S; Raboin, L-M; Hervouet, C; Toubi, L; Telismart, H; Garsmeur, O; Rousselle, Y; Pauquet, J; Nibouche, S; Glaszmann, J-C; Hoarau, J-Y; D'Hont, A

2012-09-01

Modern sugarcane cultivars (Saccharum spp., 2n = 100-130) are high polyploid, aneuploid and of interspecific origin. A major gene (Bru1) conferring resistance to brown rust, caused by the fungus Puccinia melanocephala, has been identified in cultivar R570. We analyzed 380 modern cultivars and breeding materials covering the worldwide diversity with 22 molecular markers genetically linked to Bru1 in R570 within a 8.2 cM segment. Our results revealed a strong LD in the Bru1 region and strong associations between most of the markers and rust resistance. Two PCR markers, that flank the Bru1-bearing segment, were found completely associated with one another and only in resistant clones representing efficient molecular diagnostic for Bru1. On this basis, Bru1 was inferred in 86 % of the 194 resistant sugarcane accessions, revealing that it constitutes the main source of brown rust resistance in modern cultivars. Bru1 PCR diagnostic markers should be particularly useful to identify cultivars with potentially alternative sources of resistance to diversify the basis of brown rust resistance in breeding programs.

Study of the mechanisms of humidity-induced adhesion loss of chlorinated rubber on cleaned and rusted steel substrates

International Nuclear Information System (INIS)

Chico, B.; Feliu, S.

1998-01-01

The effect of time of exposure to the humidity on the behaviour of the system chlorinated rubber paint-steel substrate (cleaned or pre-rusted) is investigated from the interfacial chemistry and adhesion points of view. After one day of humidity exposure, the paint-rust free steel substrate system shows an increase of adhesion. A maximum adhesion value is obtained after 15 days of exposure. This behaviour is similar to that previously described for a pre-rusted steel substrate. After 30-60 days of exposure, the adhesion strength values show an important reduction and the locus of adhesion loss shifts from the paint inside to the interphase between the metallic substrate and the paint. (Author) 4 refs

Formation of the Fe(II)-Fe(III) hydroxysulphate green rust during marine corrosion of steel

International Nuclear Information System (INIS)

Refait, Ph.; Memet, J.-B.; Bon, C.; Sabot, R.; Genin, J.-M.R.

2003-01-01

Rust layers formed on steel sheet piles immersed 1 m above the mud line for 25 years were analysed by Raman spectroscopy, scanning electron microscopy and elemental X-ray mappings (Fe, S, O). They consist of three main strata, the inner one mainly composed of magnetite, the intermediate one of iron(III) oxyhydroxides and the outer one of hydroxysulphate green rust GR(SO 4 2- ). Simulations of GRs formation in solutions having large [Cl - ]/[SO 4 2- ] ratios revealed that the hydroxysulphate GR(SO 4 2- ) was obtained instead of the hydroxychloride GR(Cl - ), as demonstrated by X-ray diffraction and transmission Moessbauer spectroscopy analyses. Measurements of the [S], [Fe] and [Cl] concentrations allowed us to establish that GR(SO 4 2- ) formed along with a drastic impoverishment of the solution in sulphate ions; the [Cl - ]/[SO 4 2- ] ratio increased from 12 to 240. The GR, acting like a 'sulphate pump', may favour the colonisation of the rust layers by sulphate reducing bacteria

Patterns of Urediospore Movement and Monitoring Epidemics of ...

African Journals Online (AJOL)

On the other hand, the level of stem rust severity (up to 80%) on some commercial bread wheat varieties included in this study for comparison revealed the development of high disease pressure. Durum wheat cultivars Cocorit 71, Gerardo, DZ 1928-2, DZ-2234 and CD 95759-11M showed resistant reaction to stem rust ...

Characteristics of Blister Rust Cankers on Eastern White Pine

Science.gov (United States)

William R. Phelps; Ray Weber

1969-01-01

The growth, development, and sporulation of white pine blister rust cankers were studied on eastern white pine in Wisconsin and Minnesota. Three district canker types were identified on the basis of physical appearance, growth rate, and sporulation. Canker growth rate and sporulation decreased as tree size or age increased, and many cankers apparently became inactive...

White pines, Ribes, and blister rust: integration and action

Science.gov (United States)

R. S. Hunt; B. W. Geils; K. E. Hummer

2010-01-01

The preceding articles in this series review the history, biology and management of white pine blister rust in North America, Europe and eastern Asia. In this integration, we connect and discuss seven recurring themes important for understanding and managing epidemics of Cronartium ribicola in the white pines (five-needle pines in subgenus Strobus). Information and...

Induced multiple disease resistance in wheat

International Nuclear Information System (INIS)

Borojevic, K.; Worland, A.J.

1990-01-01

Full text: The existence of genes suppressing resistance to leaf rust, stem rust and yellow rust in hexaploid wheat has been suggested. If such genes are deleted or inactivated, a more resistant variety may be obtained. In mutant lines of the wheat variety San Pastore, selected after treatment with 20,000 rad of gamma-rays, resistance to leaf rust, yellow rust, stem rust, and to some extent to Erysiphe graminis was determined. The mutants responded to infection by producing necrotic flecks in the presence of high level of disease inoculum. Similar flecks develop under stress condition. It is likely that the mother variety San Pastore carries genes for resistance which are masked by suppressor genes. Irradiation inactivates suppressors so that resistance genes which were previously masked are expressed. The first results of monosomic analysis indicate that chromosomes of groups 4 and 5 or possibly 7 may be critical for expression of resistance in the mutant lines. (author)

Control of Bean Rust using Antibiotics Produced by Bacillus and ...

African Journals Online (AJOL)

Antibiotic culture filtrates produced by Bacillus (CA5) and Streptomyces spp. were tested for translocation and persistence when applied on snap beans inoculated with rust (Uromyces appendiculatus) in greenhouse pot experiments. The antibiotics were applied on the first trifoliate leaves and translocation was assessed as ...

Developing clones of Eucalyptus cloeziana resistant to rust (Puccinia psidii)

Science.gov (United States)

Rafael F. Alfenas; Marcelo M. Coutinho; Camila S. Freitas; Rodrigo G. Freitas; Acelino C. Alfenas

2012-01-01

Besides its high resistance to Chrysoporthe cubensis canker, Eucalyptus cloeziana F. Muell. is a highly valuable tree species for wood production. It can be used for furniture, electric poles, fence posts, and charcoal. Nevertheless, it is highly susceptible to the rust caused by Puccinia psidii, which...

Damage by pathogens and insects to Scots pine and lodgepole pine 25 years after reciprocal plantings in Canada and Sweden

OpenAIRE

Fries, Anders

2017-01-01

A combined species - provenance - family experiment with Scots pine and lodgepole pine was planted in Canada and Sweden. One aim of the experiment was to evaluate the two species' sensitivities to pathogens and insects 25 years after establishment in their non-native continents. In Canada, Scots pine had better average survival than lodgepole pine, but survival rates among trees from the best seed-lots were equal. In Canada only western gall rust infected Scots pine to some extent, and mounta...