Showing papers on "Rust published in 2015"

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

Abstract: 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 stem rust management strategy.

Genome-wide association mapping for stripe rust (Puccinia striiformis F. sp. tritici) in US Pacific Northwest winter wheat (Triticum aestivum L.).

Abstract: 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.

Genome-Wide Association Mapping for Resistance to Leaf and Stripe Rust in Winter-Habit Hexaploid Wheat Landraces.

Abstract: 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.

Leaf Rust of Cultivated Barley: Pathology and Control

Abstract: 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.

Dissecting the Genetic Architecture of Leaf Rust Resistance in Wheat by QTL Meta-Analysis.

Abstract: Leaf rust is an important disease that causes significant yield losses in wheat. Many studies have reported the identification of quantitative trait loci (QTL) controlling leaf rust resistance; therefore, QTL meta-analysis has become a useful tool for identifying consensus QTL and refining QTL positions among them. In this study, QTL meta-analysis was conducted using reported results on the number, position, and effects of QTL for leaf rust resistance in bread and durum wheat. Investigation of 14 leaf rust resistance traits from 19 studies involving 20 mapping populations and 33 different parental lines provided information for 144 unique QTL that were projected onto the Wheat Composite 2004 reference map. In total, 35 meta-QTL for leaf rust resistance traits were identified in 17 wheat chromosomes and 13 QTL remained as unique QTL. The results will facilitate further work on the cloning of QTL for pyramiding minor- and partial-effect resistance genes to develop varieties with durable resistance to leaf rust.

Genetic Analysis of Rust Resistance Genes in Global Wheat

Abstract: ABSTRACT 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.

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

Abstract: 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 Batan, and 2012 and 2013 at Ciudad Obregon, 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.

First release of a fungal classical biocontrol agent against an invasive alien weed in Europe: biology of the rust, Puccinia komarovii var. glanduliferae

Abstract: The rust fungus Puccinia komarovii var. glanduliferae was first identified infecting Impatiens glandulifera in its native range (western Himalayas) between 2006 and 2010. Subsequently, it was imported into quarantine in the UK for evaluation as a classical biocontrol agent. To assess the safety of the rust, plant species relevant to Europe were tested for susceptibility. To confirm the life cycle, all infective spore stages were inoculated on I. glandulifera to follow disease progression. Teliospores were primed using bleaching and low temperatures to break dormancy. Temperature and dew period experiments using urediniospores were conducted to assess the parameters required for infection. Of the 74 plant species tested, only I. balsamina, an ornamental species, was fully susceptible to urediniospore inoculum. The life cycle of the rust – an autoecious, full-cycled species with five spore stages – was confirmed. Urediniospores were infective between 5 and 25°C, with an optimum at 15°C. A minimum of 8 h dew period was required to achieve consistent infection. Based on a pest risk assessment, the rust poses no threat to native biodiversity within EU Member States; making P. komarovii var. glanduliferae a suitable candidate as the first fungal classical biocontrol agent against an exotic weed in the region.

Sequential application of hyperspectral indices for delineation of stripe rust infection and nitrogen deficiency in wheat

Abstract: Nitrogen (N) fertilization is crucial for the growth and development of wheat crops, and yet increased use of N can also result in increased stripe rust severity. Stripe rust infection and N deficiency both cause changes in foliar physiological activity and reduction in plant pigments that result in chlorosis. Furthermore, stripe rust produce pustules on the leaf surface which similar to chlorotic regions have a yellow color. Quantifying the severity of each factor is critical for adopting appropriate management practices. Eleven widely-used vegetation indices, based on mathematic combinations of narrow-band optical reflectance measurements in the visible/near infrared wavelength range were evaluated for their ability to discriminate and quantify stripe rust severity and N deficiency in a rust-susceptible wheat variety (H45) under varying conditions of nitrogen status. The physiological reflectance index (PhRI) and leaf and canopy chlorophyll index (LCCI) provided the strongest correlation with levels of rust infection and N-deficiency, respectively. When PhRI and LCCI were used in a sequence, both N deficiency and rust infection levels were correctly classified in 82.5 and 55 % of the plots at Zadoks growth stage 47 and 75, respectively. In misclassified plots, an overestimation of N deficiency was accompanied by an underestimation of the rust infection level or vice versa. In 18 % of the plots, there was a tendency to underestimate the severity of stripe rust infection even though the N-deficiency level was correctly predicted. The contrasting responses of the PhRI and LCCI to stripe rust infection and N deficiency, respectively, and the relative insensitivity of these indices to the other parameter makes their use in combination suitable for quantifying levels of stripe rust infection and N deficiency in wheat crops under field conditions.

Single component air-drying water-based rust inhibiting primer with curtaining capacity and used for electrical equipment housing as well as preparation method of primer

Abstract: The invention discloses single component air-drying water-based rust inhibiting primer with curtaining capacity and used for an electrical equipment housing. The primer comprises components in percentage by weight as follows: 30%-50% of water-based resin, 1%-5% of a wetting dispersant, 0.1%-1% of a pH regulator, 5%-15% of rust inhibiting pigment, 15%-30% of pigment packing, 1%-8% of a coalescing agent, 0.5%-1.5 % of a wetting levelling agent, 0.5%-2% of a flash rust remover, 0.1%-1.5% of an antifoaming agent, 0.5%-2% of a thickener, 0.1%-1% of a mould-proof sterilizing agent and 5%-20% of deionized water. The invention further discloses a preparation method of the water-based rust inhibiting primer. The water-based rust inhibiting primer has lower film forming temperature, any cross-linking agent and curing agent is not required to be added, the primer can be rapidly dried and cured at normal temperature or a low-temperature baking environment ranging from 50 DEG C to 80 DEG C, construction is simple and convenient, and the product performance is comparable with that of solvent based paint.

Corrosion Behavior of E690 High-Strength Steel in Alternating Wet-Dry Marine Environment with Different pH Values

Abstract: The corrosion behavior and mechanism of E690 high-strength steel in marine environment with different pH values were studied through electrochemical technology and long-term alternating wet-dry cycle experiments combined with SEM and XRD. Results showed that the corrosion current density of E690 high-strength steel gradually increased with decreased pH. After long-term tests in alternating wet-dry marine environment with various pH values, uniform corrosion mainly occurred on E690 steel, accompanied by vast corrosion pitting. Weight loss analysis demonstrated that corrosion rate decreased with increased pH. Moreover, corrosion mechanism varied with pH, and hydrogen-evolution reaction greatly increased the E690 steel corrosion rate at low pH. Meanwhile, the compositions of corrosion products slightly differed with pH; these products consisted of Fe3O4, Fe2O3, α-FeOOH, β-FeOOH, γ-FeOOH, and amorphous substances. However, the rust-layer density varied. Cr in the rust layer promoted the densification of rust layer and improved the decay resistance of E690 steel.

Monitoring the development of rust layers on weathering steel using in situ Raman spectroscopy under wet-and-dry cyclic conditions

Abstract: The change of rust composition on weathering steel was consecutively monitored by in situ Raman spectroscopy during exposure to atmosphere under cyclic 4 h wet-4 h dry condition for 144 h in the presence of NaCl deposit. Raman spectra of the rust surface in the presence of NaCl deposit at 0.93 mg cm−2 corresponded to those of lepidocrocite (γ–FeOOH) and magnetite (Fe3O4) in the initial 12 h exposure. After 12 h exposure, akaganeite (β–FeOOH) started to form, and its molar ratio on the rust surface increased to 90 % at 30 h exposure. The Raman spectra further changed after 30 h exposure in which γ–FeOOH again emerged. The reappearance of γ–FeOOH is assumed to be caused by capture of chloride ions in β–FeOOH resulting in the decrease of free chloride ions in the surface solution layer. When the amount of NaCl deposit was decreased to 0.11 mg cm−2, the surface was covered with dark brown corrosion product which may be amorphous FeOOH and after repeated dry-wet cycles, yellow-brown spots emerged which consisted of β–FeOOH.

Rust exfoliation on carbon steels in chloride-rich atmospheres

Abstract: Abstract The exposure of carbon steel in marine atmospheres can lead in certain circumstances to the formation of thick rust layers (containing a number of compact laminas) that are easily detached (exfoliated) from the steel substrate, leaving it unprotected and considerably accelerating the corrosion process. This deterioration phenomenon is of particular concern in steel infrastructures located close to the sea (civil constructions, bridges, etc.), whose service lifetime can be extraordinarily limited. High times of wetness of the metallic surface and high chloride ion deposition rates play a decisive role in the formation of this type of rust. Research has been carried out for 1 year in eight pure marine atmospheres with annual average chloride deposition rates of 70–1906 mg Cl-/m2 day. The studied carbon steels consisted of one mild steel, one conventional weathering steel (Corten A), and one high nickel (~3 wt.%) advanced weathering steel (AWS). The paper describes the environmental conditions that lead to the formation of these thick multilaminar rust layers and presents a characterisation study of this singular type of rust using a variety of analysis techniques: scanning electron microscopy/energy-dispersive X-ray spectroscopy, X-ray diffraction, Mössbauer spectroscopy, and transmission electron microscopy/electron diffraction. The Ni-AWS shows greater resistance to the occurrence of rust exfoliation.

Asian Soybean Rust Resistance: An Overview

Abstract: Asian soybean rust caused by Phakopsora pachyrhizi, occurs in all soybean production regions of the world Rust is the most destructive foliar disease of soybean and can cause yield losses of over 80% To date, six race-specific resistance genes have been identified in plant introductions However, races of P pachyrhizi able to overcome the resistance conferred by these genes have evolved Due to the limited availability of resistant varieties, fungicide application is the only management tool available for farmers, which significantly raises the production cost and the risk of environmental and human contamination Thus, the transfer of resistance genes through classical breeding followed by marker-assisted selection allows the development of resistant varieties and their use as an efficient and cost-effective method for controlling soybean rust The objective of this review is to provide a broad overview of the Asian soybean rust resistance, and a useful tool to guide future researches as well

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

Abstract: 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 05 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

Evaluation of Detached Leaf Assay for Assessing Leaf Rust (Puccinia triticina Eriks.) Resistance in Wheat

Abstract: The use of resistant cultivars is the most economical and effective method to control leaf rust of wheat caused by Puccinia triticina Eriks. Generally screening of wheat germplasm for resistance to rusts is carried out in the greenhouse and field conditions using seedling and adult plants. However, these screening trails are influenced by environmental factors and limit the number of races to be evaluated simultaneously. In the present study, a detached leaf assay was evaluated for screening of wheat germplasm resistance to leaf rust. As treatments, two senescence retardant chemicals (benzimidazole and kinetin) at different concentrations and combinations were added to 5% water-agar. The selected media was further validated in 20 wheat genotypes using three leaf rust races. The media containing 10 mg/L kinetin and 30 mg/L benzimidazole inoculated using an atomizer was the best in delaying the senescence and thereby increasing the sporulation. A positive correlation (r=0.9) between the detached leaf assay and the whole seedling assay infection types was observed. The standard errors for detached leaf and whole seedling assays were 0.24 and 0.3, respectively. The low standard errors further confirm the consistency of the disease response rating between the two assays. Generally this study revealed that the infection types were found to be similar both in detached leaf and whole seedlings assay. Therefore, detached leaf assay can be used to assess wheat genotypes against leaf rust.

Resistance to late leaf spot and rust diseases in ICRISAT’s mini core collection of peanut ( Arachis hypogaea L.)

Abstract: Late leaf spot (LLS) (Phaeoisariopsis personata) and rust (Puccinia arachidis) are major foliar diseases of peanut causing significant losses worldwide. Identification and infusion of resistance into peanut cultivars is important in the management of these diseases. The present study therefore aimed at screening the peanut mini core collection to identify potential sources of resistance to these diseases. Two separate field experiments were conducted for screening LLS and rust under artificial epiphytotic conditions during rainy seasons of 2012 and 2013 at ICRISAT, Patancheru, India. The trials were laid in a randomized complete block design on beds with three replications. Data on LLS and rust disease severities were collected using 1 to 9 scales at 75, 90 and 105 days after sowing (DAS), and pod yields were recorded at harvest. Results indicate significant variations among accessions for LLS and rust resistance. Mean of 2 years study revealed that 53 accessions were moderately resistant (MR), 86 accessions were susceptible (S) and 45 accessions were highly susceptible (HS) to LLS. For rust disease, 10 accessions were resistant (R), 115 accessions were with ‘MR’ reaction and 59 accessions with susceptible (S) reaction. Six superior accessions in terms of combined disease resistance and yield (ICGs 4389, 6993, 11426, 4746, 6022, 11088) were selected and the disease progress curves, for each, were generated. Highest yields were recorded with ICG 11426 in LLS and rust plots. Overall, our results indicate that these six accessions can be potential sources of LLS and rust resistance.

A QTL on chromosome 5BL in wheat enhances leaf rust resistance of Lr46

Abstract: Combinations of effective leaf rust resistance genes that condition resistance to many leaf rust races are key to the development of wheat cultivars with long-lasting resistance to leaf rust caused by Puccinia triticina. A population of F6 recombinant inbred lines (RILs) derived from the cross ‘Thatcher*3/Americano 25e’ was evaluated for segregation of adult plant leaf rust resistance in three field plot tests and in a greenhouse test. A genetic map was constructed with 243 diversity array technology markers. Significant effects for reduction in leaf rust severity were found on chromosomes 1BL and 5BL. The sequence-tagged site marker csLV46, closely linked to Lr46, mapped to the logarithm of odds peak on chromosome 1BL, indicating that the RILs were likely segregating for this adult plant resistance gene. Lines with csLV46 had an average leaf rust severity of 35 % in the four tests. RILs with the resistance on chromosome 5BL designated as QLr.cdl-5BL had an average leaf rust severity of 47 %. RILs with both csLV46 and QLr.cdl-5BL had an average leaf rust severity of 22 %, close to the Thatcher*2/Americano 25e parental line. Lines that lacked both csLV46 and QLr-5BL had an average severity of 56 %. The QLr.cdl-5BL region enhanced the leaf resistance conditioned by Lr46 in an additive manner.

Convenient and fast efficient steel pipe rust removal grinding machine

Abstract: The invention discloses a convenient and fast efficient steel pipe rust removal grinding machine. The convenient and fast efficient steel pipe rust removal grinding machine comprises a workbench, a motor fixing table, a rust removing device, a scrap iron clearing device and a protective cover. The rust removing device comprises a rust removing brush head and a rust removing roller. The rust removing brush head is connected with the bottom face of the motor fixing table through adjusting rods. The rust removing roller comprises a rust removing barrel body which is evenly provided with installing ports. Steel wire brushes are arranged in the installing ports and fixed through fastening pieces. The scrap iron clearing device comprises a chip removing funnel and a chip collecting device. The convenient and fast efficient steel pipe rust removal grinding machine is simple in structure and high in practicability; by improving the rust removing device, rust removal can be performed on the interior and the surface of a steel pipe at the same time, and operation can be more convenient and easier; due to design of a clamping jaw and a bracket, the steel pipe can be fixed more firmly; meanwhile, by adjusting the clamping jaw and the bracket, rust removal can be performed on steel pipes of different pipe diameters, the using range of the steel pipe rust removal grinding machine is further widened, and comprehensive utilizing efficiency is improved.

Survey of Rust and Septoria Leaf Blotch Diseases of Wheat in Central Ethiopia and Virulence Diversity of Stem Rust Puccinia graminis f. sp.tritici

Abstract: Wheat is one of the most important cereal crops in Ethiopia and produced across large area of the country. Production of the crop constrained by several infection diseases including rust and Septoria leaf blotch diseases which are the major bottle neck of wheat production in Ethiopia. The objective of this study was to ass distribution, incidence and severity of wheat rusts and Septoria leaf blotch in west and South West Shewa zones and identification of Puccinia graminis f.sp. tritici virulences in Ethiopia. The survey was made in 2013 main cropping season (from September to October) following the main roads and accessible routes in each survey district, and stops were made at every 5 km intervals based on vehicles odometers as per wheat fields available. Five stops were made in each wheat field by moving “W” fashion at each stop interval using quadrants and data were collected from each. Race analysis was carried out by inoculating single uredinial isolates on to the 20 differential hosts. The result indicated that, stem, leaf and yellow rust mean incidence value 54.7%, 19.4% and 7.7% were recorded in the surveyed areas, respectively and mean severity value of 7.0%, 9.7% and 5.5% in the same order. Septoria leaf blotch was the most prevalent disease with100%. Mean incidence of 83% and 0.44 disease index of Septoria leaf blotch were recorded. The most widely grown Varieties Digelu and Kakaba showed susceptible reaction to stem and leaf rust whereas Meda wolabu were free both rusts. Variety Kubisa were susceptible to the three rusts (stem, leaf and yellow). Out of 20 isolates, two races namely TTKSK and TKTTF were identified. Race TTKSK was the most frequent with 95%. Stem rust resistance genes Sr36, SrTmp and Sr24 were effective against TTKSK and while, Sr8a, Sr24 and Sr31 were effective against TKTTF (Digelu race). Most of the genes possessed by the differentials were ineffective against one or more of the tested isolates except Sr24. Sr24 which confer resistance against most of the races detected and prevalent in Ethiopia can be used in breeding for resistance to stem rust in the country.

Mapping of gene conferring adult-plant resistance to stripe rust in Chinese wheat landrace Baidatou

Abstract: Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a destructive foliar disease of wheat worldwide. Sustainable control of the disease is preferably achieved by deploying stripe rust resistance genes in wheat cultivars. Our previous studies have shown that Baidatou, a Chinese wheat landrace, displayed good adult-plant resistance (APR) to wheat stripe rust in Gansu Province, an epidemic region for stripe rust in China. To elucidate the genetic basis of APR to stripe rust in Baidatou, a cross between Baidatou and Mingxian 169, which is susceptible to all the known Chinese (Pst) races, was performed. Adult plants of F1, F2 and F2:3 generations derived from the cross Mingxian 169/Baidatou were inoculated in the field with the most prevalent Chinese Pst race, CYR33, in Yangling, Shaanxi Province, during 2009–2010 and 2010–2011 crop seasons, respectively. The results showed that the resistance of Baidatou to stripe rust was conferred by a single dominant gene. Six hundred and sixty simple sequence repeat (SSR) markers and 128 sequence-related amplified polymorphism (SRAP) markers were screened for association with the resistance gene to stripe rust using bulked segregant analysis. Four polymorphic SSR markers and two SRAP markers were identified to be linked to the resistance gene. A linkage map was constructed with six molecular markers and the resistance gene. The genetic distance of two flanking SSR markers to the resistance gene, temporarily designated YrBai, was 3.6 and 5.4 cM, respectively. Based on the position of the SSR markers on the wheat chromosome, YrBai was located on chromosome 6DS. According to the rust reaction patterns, SSR marker allele analysis and the pedigree of the Yr genes on chromosome 6D, YrBai is likely to be a novel APR gene against stripe rust. The specificity of the two flanking markers of YrBai was validated in 99 wheat germplasms. The gene and its flanking markers should be useful for developing wheat cultivars with durable resistance.

Marker-trait association and epistasis for brown rust resistance in sugarcane

Abstract: Sugarcane brown rust, caused by Puccinia melanocephala, is one of the major sugarcane diseases. The detection of molecular markers associated to brown rust resistance and also of its epistatic interactions were investigated in a mapping population obtained by crossing the brown rust susceptible clone IACSP953018 and the resistant cultivar IACSP933046. Resistance was evaluated in a field trial in plant cane and first ratoon under natural infection and scored using a diagrammatic scale from 1 (most resistance) to 9 (most susceptible). A total of 488 single dose markers (amplified fragment length polymorphism AFLP, genomic microsatellite gSSR and expressed sequence tag derived microsatellites EST-SSRs) were evaluated through a single marker trait association approach for brown rust resistance. Sixty one putative quantitative trait alleles (QTA) for brown rust (30 in plant cane, 31 in ratoon cane; 10 of them was common for both crop years) were detected of which several were related to resistance. Twenty one (34 %) of the markers associated to QTA derived from ESTs. Some of them have similarity to genes/proteins related to disease response pathways. The estimates of the proportion of the total phenotypic variation ( $$\hat{R}^{2}$$ ) explained by each significant main QTA effect ranged from 1.84 to 7.22 %, while the total explained variance estimates were 37.25 % (plant cane) and 43.26 % (ratoon cane) considering all main significant QTA effects. Fifty significant digenic epistatic interactions were suggested with the majority (68 %) contributing to increase brown rust resistance. Together, these probable epistatic effects explain 16.26 % (plant cane) and 17.22 % (ratoon cane) of the total phenotypic variance. Although evidence of epistasis was observed, linkage cannot be ruled out as the majority of the markers involved in the digenic interaction could not be addressed to any linkage group. The results suggest that epistasis may have an important contribution on sugarcane resistance to brown rust.

Yield gain due to fungicide application in varieties of winter wheat (Triticum aestivum) resistant and susceptible to leaf rust

Abstract: In three independent experiments in Turkey and Kazakhstan, winter wheat germplasm with variable degrees of resistance to leaf rust was subjected to fungicide protection. The yield loss of genotypes susceptible to leaf rust varied from 30% to 60% depending on the environment and severity of infection. Genotypes completely or moderately resistant to leaf rust also responded positively to fungicide protection, with average yield increases in the range 10–30%. This increase was observed even in one season without leaf rust infection. The main character affected by fungicide was 1000-kernel weight. There was stable expression of the magnitude of yield gain in resistant genotypes in different seasons, confirming genetic variation for this trait. Possible mechanisms of yield gain from fungicide protection in resistant genotypes are related to a positive physiological effect of the chemical used as well as a possible ‘cost of resistance’ to wheat plants. The magnitude of yield gain by resistant germplasm justifies its capture in breeding programs to develop varieties resistant to diseases and with greater benefits from the fungicide protection.

Appraisal of wheat germplasm for adult plant resistance against stripe rust

Abstract: The resurgence of wheat stripe rust is of great concern for world food security. Owing to resistance breakdown and the appear- ance 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 condi- tions 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-mod- erately resistant, one moderately resistant-to-moderately susceptible, 5 moderately susceptible-to-susceptible, one moderately suscepti- ble, 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 among 21 were derived from parents of CIMMYT origin. Cluster analysis was executed to determine the diversity among the wheat genotypes based on stripe rust resistance and yield parameters. All genotypes were grouped into nine clusters exhibiting a high level of diversity at a 25% linkage distance. There were 29 wheat lines resistant to stripe rust that were grouped into the first three clusters, while 4 high-yielding lines were in Cluster VIII. The susceptible check, Morocco, was separated from rest of lines and fell in the last cluster i.e. Cluster IX. Based on the results, inter-crossing immune/ resistant lines is recommended, and with high yielding lines − it is also recommended that cultivars with improved disease resistance and yield potential be developed.

Water-based rust conversion paint and preparation method thereof

Abstract: The invention discloses a water-based rust conversion paint and a preparation method thereof. For an existing rust conversion coating, a commonly used rust converting agent is acidic, and an acidic condition is required for an iron rust conversion process. The acidic rust converting agent can damage the stability of a commonly used alkaline emulsion. The water-based rust conversion paint comprises the components of, by mass, 30-47 parts of an aqueous polymer emulsion, 2-12 parts of a rust converting agent, 3-17 parts of a coloring pigment, 3-20 parts of an anti-rust pigment, 4-8 parts of a filler, 0.1-0.5 part of a deforming agent, 0.1-1 part of a dispersing agent, 0.5-4 parts of a film coalescing aid, 0.1-2 parts of an emulsion stabilizer, 0.1-0.5 part of a thickeners, 0.1-0.5 part of a mildew preventive, and 10-35 parts of water. The paint has good stability, and excellent rust layer conversion effect. A coating formed with the paint has good corrosion resistance. The paint is suitable for steel rusty surface rust conversion and corrosion prevention, and is mainly used as a primer.

Assessment of rust layers formed on weathering steel in saline environment by gas adsorption

Abstract: The rusts of different kinds of weathering steels and mild steel formed by CCT and exposure to a coastal atmosphere were examined by the adsorption of nitrogen and water molecules. The specific surface area (S) of the rusts was determined from the adsorption isotherms. The rusts of the weathering steels showed higher S and smaller particle size than those of the mild steel, indicating that the weathering steels form more compact rust layers compared to the mild steel. The S of the rusts formed at different positions of a simulated girder located in the coast strongly depended on the setting position.