Search

The adoption of agriculture in several parts of the world during the early Neolithic period led to a fundamental change in human migration. By introducing newly domesticated crops into new environments, pathogens and parasites were also inadvertently transferred from their regions of origin and underwent a considerable population growth. In the newly settled regions, some pests of indigenous plants adapted to new crops by host switching. This review is limited to three basic migration events and mainly to agricultural crops of the temperate zone: (1) the migration of the first farmers from SE Asia to Europe, (2) European expansion from the 16th century onward, (3) modern globalization since the 20th century. Molecular analyses offer the opportunity to study the evolutionary history of pest populations, their origin and dynamics and their spread around the world. Cereals' rusts and powdery mildew, storage insects were the first to spread with wheat species, barley, and pulses from the Levant across Eurasia. The Columbian exchange of crops to and from the Americas brought entirely new pests to Europe while old world pathogens spread to the Americas and subsequently to all other regions colonized by Europeans. Modern globalization further facilitated the spread of pathogens and insects worldwide, as previously inconceivable amounts of agricultural products, business travelers, and maybe tourists have elevated global accessibility. This is illustrated by case studies based on fungi and insects. In the near future, pests will have colonized all crops in all countries where they can exist according to their agro-climatic requirements. [ABSTRACT FROM AUTHOR]

Sugarcane rust incited by Puccinia melanocephala (brown rust) and P. kuehnii (orange rust) becomes very severe under warm,moist climatic conditions. Though there were methods to screen rust resistance under artificial conditions where rust is prevalent, there is no method to screen the rust resistance in a place where rust occurrence is not regular and severe. To overcome this problem, a simple method was devised to screen sugarcane leaves challenged with rust uredospores and maintaining the setup under optimum relative humidity and temperature for 15-20 days for identifying the rust resistant sugarcane clones. This method of rust screening is simple and easy, fast and reliable and many clones can be screened in short period of 20 days.

Sustainable global wheat production requires wheat varieties, that are sufficiently resistant to the main wheat diseases. The economically important fungal pathogens worldwide include powdery mildew (PM), yellow rust (YR), leaf rust (LR) and blotch causing pathogens including Septoria nodorum blotch (SNB) and Septoria tritici blotch (STB). Here, we present the evaluation of winter wheat varieties of diverse origin against the prevalent local populations of PM, YR, LR, STB and SNB under natural infection conditions through image-based phenotyping in two consecutive years (2019 and 2020). We found several varieties to be resistant against multiple diseases. Following the association mapping, we obtained a total of 206 marker trait associations for all the parameters scored which were condensed to 79 quantitative trait loci (QTLs) (eight QTLs for PM, 25 QTLs for LR, 11 QTLs for YR, 19 QTLs for SNB and eight QTLs for STB) based on the linkage disequilibrium among the molecular markers. The known genes present at these QTLs are discussed in detail. The varieties resistant to multiple diseases, identified with the QTLs and molecular markers can be considered as elite raw material for future wheat breeding.

Application of physical modification techniques such as the radiation of gamma rays could induce rust resistance and improve the performance of wheat plants through the development of new products. During the growing seasons of 2020-2021 and 2021-2022, two field experiments were done to see how well five types of bread wheat (NING MAI 50-0CHN, SAKHA 93, GIZA 168, SIDS 12, and SKAUZ) did when they were exposed to 5, 10, 15, 20, and 25 Kr of gamma rays. The experiments looked at how well the rust was controlled, how much yield was produced, and how the seedlings grew. Results showed that wheat genotypes significantly differed in rust infection and other parameters in both seasons at different gamma-ray ratios. Sakha 93 gave high resistance to yellow rust with high seedling dry weight and seedling vigor index 2, but Giza 168 gave the highest leaf rust resistance with increased doses of gamma rays. On the other hand, the SKAUZ genotype surpassed other genotypes in germination percentage and grain yield in both seasons. A dose of 25 kr was the most beneficial for rust resistance and yield attributes in comparison to the control, while a dose of 5 kr caused improvement in seedling parameters. Results exhibited that the interaction effect between wheat genotypes and gamma rays was significant on all studied traits in both seasons. Finally, it is concluded that gamma rays play an important role in inducing rust resistance and improving grain yield. [ABSTRACT FROM AUTHOR]

Wheat is a crop of historical significance, as it marks the turning point of human civilization 10,000 years ago with its domestication. Due to the rapid increase in population, wheat production needs to be increased by 50% by 2050 and this growth will be mainly based on yield increases, as there is strong competition for scarce productive arable land from other sectors. This increasing demand can be further achieved using sustainable approaches including integrated disease pest management, adaption to warmer climates, less use of water resources and increased frequency of abiotic stress tolerances. Out of 200 diseases of wheat, 50 cause economic losses and are widely distributed. Each year, about 20% of wheat is lost due to diseases. Some major wheat diseases are rusts, smut, tan spot, spot blotch, fusarium head blight, common root rot, septoria blotch, powdery mildew, blast, and several viral, nematode, and bacterial diseases. These diseases badly impact the yield and cause mortality of the plants. This review focuses on important diseases of the wheat present in the United States, with comprehensive information of causal organism, economic damage, symptoms and host range, favorable conditions, and disease management strategies. Furthermore, major genetic and breeding efforts to control and manage these diseases are discussed. A detailed description of all the QTLs, genes reported and cloned for these diseases are provided in this review. This study will be of utmost importance to wheat breeding programs throughout the world to breed for resistance under changing environmental conditions. [ABSTRACT FROM AUTHOR]

Sustainable global wheat production requires wheat varieties, that are sufficiently resistant to the main wheat diseases. The economically important fungal pathogens worldwide include powdery mildew (PM), yellow rust (YR), leaf rust (LR) and blotch causing pathogens including Septoria nodorum blotch (SNB) and Septoria tritici blotch (STB). Here, we present the evaluation of winter wheat varieties of diverse origin against the prevalent local populations of PM, YR, LR, STB and SNB under natural infection conditions through image-based phenotyping in two consecutive years (2019 and 2020). We found several varieties to be resistant against multiple diseases. Following the association mapping, we obtained a total of 206 marker trait associations for all the parameters scored which were condensed to 79 quantitative trait loci (QTLs) (eight QTLs for PM, 25 QTLs for LR, 11 QTLs for YR, 19 QTLs for SNB and eight QTLs for STB) based on the linkage disequilibrium among the molecular markers. The known genes present at these QTLs are discussed in detail. The varieties resistant to multiple diseases, identified with the QTLs and molecular markers can be considered as elite raw material for future wheat breeding. [ABSTRACT FROM AUTHOR]

Wheat is a crop of historical significance, as it marks the turning point of human civilization 10,000 years ago with its domestication. Due to the rapid increase in population, wheat production needs to be increased by 50% by 2050 and this growth will be mainly based on yield increases, as there is strong competition for scarce productive arable land from other sectors. This increasing demand can be further achieved using sustainable approaches including integrated disease pest management, adaption to warmer climates, less use of water resources and increased frequency of abiotic stress tolerances. Out of 200 diseases of wheat, 50 cause economic losses and are widely distributed. Each year, about 20% of wheat is lost due to diseases. Some major wheat diseases are rusts, smut, tan spot, spot blotch, fusarium head blight, common root rot, septoria blotch, powdery mildew, blast, and several viral, nematode, and bacterial diseases. These diseases badly impact the yield and cause mortality of the plants. This review focuses on important diseases of the wheat present in the United States, with comprehensive information of causal organism, economic damage, symptoms and host range, favorable conditions, and disease management strategies. Furthermore, major genetic and breeding efforts to control and manage these diseases are discussed. A detailed description of all the QTLs, genes reported and cloned for these diseases are provided in this review. This study will be of utmost importance to wheat breeding programs throughout the world to breed for resistance under changing environmental conditions.

Switchgrass rust caused by Puccinia novopanici (P. novopanici) has the ability to significantly affect the biomass yield of switchgrass, an important biofuel crop in the United States. A comparative genome analysis of P. novopanici with rust pathogen genomes infecting monocot cereal crops wheat, barley, oats, maize and sorghum revealed the presence of larger structural variations contributing to their genome sizes. A comparative alignment of the rust pathogen genomes resulted in the identification of collinear and syntenic relationships between P. novopanici and P. sorghi; P. graminis tritici 21–0 (Pgt 21) and P. graminis tritici Ug99 (Pgt Ug99) and between Pgt 21 and P. triticina (Pt). Repeat element analysis indicated a strong presence of retro elements among different Puccinia genomes, contributing to the genome size variation between ~1 and 3%. A comparative look at the enriched protein families of Puccinia spp. revealed a predominant role of restriction of telomere capping proteins (RTC), disulfide isomerases, polysaccharide deacetylases, glycoside hydrolases, superoxide dismutases and multi-copper oxidases (MCOs). All the proteomes of Puccinia spp. share in common a repertoire of 75 secretory and 24 effector proteins, including glycoside hydrolases cellobiohydrolases, peptidyl-propyl isomerases, polysaccharide deacetylases and protein disulfide-isomerases, that remain central to their pathogenicity. Comparison of the predicted effector proteins from Puccinia spp. genomes to the validated proteins from the Pathogen–Host Interactions database (PHI-base) resulted in the identification of validated effector proteins PgtSR1 (PGTG_09586) from P. graminis and Mlp124478 from Melampsora laricis across all the rust pathogen genomes. [ABSTRACT FROM AUTHOR]

The rust fungi (Pucciniales) are among the most common and devastating pathogens of field crops and forest tree species worldwide. Given the importance of the rusts in agriculture and forestry, this Special Issue of the Canadian Journal of Plant Pathology brings together a variety of papers on rust disease management and biology. The Special Issue comprises 16 full-length articles on rust pathogens of field crops and white pine. Two are review articles summarizing recent advances in rust pathology, two are first reports of new pathogens/diseases in new geographical territories, and 12 articles present results that advance knowledge of rust pathogens in the areas of pathogen population biology, host—pathogen interactions, and resistance breeding. We trust that the articles assembled in this Special Issue will highlight the power of virulence phenotyping coupled with genetic mapping for building durable rust resistance in staple crops such as wheat, as well as the ongoing need for research on rust fungi in field crops and forest trees. [ABSTRACT FROM AUTHOR]

To study the genetic basis of pleiotropic resistance to rusts and powdery mildew in hexaploid wheat, three Egyptian cultivars, Misr-1, Sids-13 and Sakha-94 were crossed to three CIMMYT cultivars carrying pleiotropic resistance genes i.e., Pavon-76 (Sr2/Yr30/Lr27, Lr46/Yr29/Sr58/Pm39), Jupateco-73-R (Lr34/Yr18/Sr57/Pm38) and Seri-82 (Lr26/Sr31/Yr9). In F2 progeny test, no segregation was found in four crosses, Pavon-76/Misr-1, Pavon-76/Sids-13, Jupateco-73-R/Sids-13, and Jupateco-73-R/Sakha-94, indicating the dominance of pleiotropic adult plant resistance (PAPR). Segregation ratios of the other five crosses fitted the expected ratios indicating the absence of these genes in the tested Egyptian cultivars. There was a difference between each of the two parents that was controlled by digenic recessive or dominance. Molecular screening revealed that three PAPR genes Sr2/Yr30/Lr27, Lr46/Yr29/Sr58/Pm39 and Lr34/Yr18/Sr57/Pm38 were present in the majority of resistant F2 plants, while, race-specific gene Lr26/Sr31/Yr9 was present mostly in susceptible F2 plants. PAPR genes should be considered for marker-assisted wheat breeding. [ABSTRACT FROM AUTHOR]

Corrosion of steels in deep, cold, low oxygen sea waters over many decades often is attributed to microbiologically influenced corrosion (MIC). Herein it is argued that the available evidence does not support this proposition since (a) the few available in-situ deep sea field observations are consistent with long-term corrosion under abiotic conditions and (b) independent environmental studies indicate dissolved inorganic nitrogen, a necessary nutrient for MIC, is likely negligible or very low in deep sea waters. On that basis it is proposed that the rusticles observed on some shipwrecks, such as the Titanic, largely are the result of formation of ferrous hydroxides from ferrous ions released, very slowly, from the oxidation of magnetite rusts to maghemite. Direct evidence for this proposition is not available in-situ but is consistent with field observations and laboratory results. [ABSTRACT FROM AUTHOR]

Twenty-three wheat genotypes were evaluated for stripe and leaf rusts, caused by Puccinia striiformis f. sp. tritici and Puccinia triticina f. sp. tritici, respectively, at seedling and adult stages under greenhouses and field conditions during the 2019/2020 and 2020/2021 growing seasons. The race analysis revealed that 250E254 and TTTST races for stripe and leaf rusts, respectively were the most aggressive. Eight wheat genotypes (Misr-3, Misr-4, Giza-171, Gemmeiza-12, Lr34/Yr18, Lr37/Yr17, Lr46/Yr29, and Lr67/Yr46) were resistant to stripe and leaf rusts at seedling and adult stages. This result was confirmed by identifying the resistance genes: Lr34/Yr18, Lr37/Yr17, Lr46/Yr29, and Lr67/Yr46 in these genotypes showing their role in the resistance. Sids-14 and Shandweel-1 genotypes were susceptible to stripe and leaf rusts. Twelve crosses between the two new susceptible wheat genotypes and the three slow rusting genes (Lr34/Yr18, Lr37/Yr17, and Lr67/Yr46) were conducted. The frequency distribution of disease severity (%) in F2 plants of the twelve crosses was ranged from 0 to 80%. Resistant F2 plants were selected and the resistance genes were detected. This study is important for introducing new active resistance genes into the breeding programs and preserving diversity among recently released wheat genotypes. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Agronomy is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sugarcane rust incited by Puccinia melanocephala (brown rust) and P. kuehnii (orange rust) becomes very severe under warm, moist climatic conditions. Though there were methods to screen rust resistance under artificial conditions where rust is prevalent, there is no method to screen the rust resistance in a place where rust occurrence is not regular and severe. To overcome this problem, a simple method was devised to screen sugarcane leaves challenged with rust uredospores and maintaining the setup under optimum relative humidity and temperature for 15-20 days for identifying the rust resistant sugarcane clones. This method of rust screening is simple and easy, fast and reliable and many clones can be screened in short period of 20 days. [ABSTRACT FROM AUTHOR]

Switchgrass rust caused by Puccinia novopanici (P. novopanici) has the ability to significantly affect the biomass yield of switchgrass, an important biofuel crop in the United States. A comparative genome analysis of P. novopanici with rust pathogen genomes infecting monocot cereal crops wheat, barley, oats, maize and sorghum revealed the presence of larger structural variations contributing to their genome sizes. A comparative alignment of the rust pathogen genomes resulted in the identification of collinear and syntenic relationships between P. novopanici and P. sorghi; P. graminis tritici 21–0 (Pgt 21) and P. graminis tritici Ug99 (Pgt Ug99) and between Pgt 21 and P. triticina (Pt). Repeat element analysis indicated a strong presence of retro elements among different Puccinia genomes, contributing to the genome size variation between ~1 and 3%. A comparative look at the enriched protein families of Puccinia spp. revealed a predominant role of restriction of telomere capping proteins (RTC), disulfide isomerases, polysaccharide deacetylases, glycoside hydrolases, superoxide dismutases and multi-copper oxidases (MCOs). All the proteomes of Puccinia spp. share in common a repertoire of 75 secretory and 24 effector proteins, including glycoside hydrolases cellobiohydrolases, peptidyl-propyl isomerases, polysaccharide deacetylases and protein disulfide-isomerases, that remain central to their pathogenicity. Comparison of the predicted effector proteins from Puccinia spp. genomes to the validated proteins from the Pathogen–Host Interactions database (PHI-base) resulted in the identification of validated effector proteins PgtSR1 (PGTG_09586) from P. graminis and Mlp124478 from Melampsora laricis across all the rust pathogen genomes.

Kazakhstan-Siberia Network for Spring Wheat Improvement (KASIB) was established in 2000 to conduct multi-location cooperative yield trials for the exchange of breeding material and to evaluate agronomic traits such as grain yield and disease resistance. In 2016, aggregated KASIB data were analyzed and 120 cultivars and breeding lines demonstrating different degrees of resistance to leaf rust selected. They were tested for leaf rust and agronomic traits in Omsk, Russia; Almaty, Kazakhstan and Sakarya, Turkey in 2017–2019. This germplasm was grouped into four categories based on leaf rust reaction: 31 resistant (R), 27 moderately resistant (MR), 37 intermediate (M) and 25 moderately susceptible (MS) entries. Lr genes were postulated based on tests using pathotypes with known virulence profiles and molecular markers. The most frequent Lr genes alone or in combination were Lr10 (31 entries), Lr26 (24), Lr9 (23), Lr1 (18), Lr17 (11), Lr34 (11) and Lr19 (7). Genes Lr1, Lr9, Lr10 and Lr17 reduced the leaf rust severity to M or MS across environments. The presence of Lr26 alone or in combination with other major genes reduced the leaf rust severity to MR-M in Omsk and R in Sakarya. The only gene with the large effect on leaf rust was Lr19, which provided a high level of resistance at all sites both alone and in combination with Lr26. Leaf rust severity in 52 entries with adult plant resistance (APR) was compared to 68 entries possessing effective seedling resistance genes. The leaf rust severity in entries with APR compared to seedling resistance was similar at low infection pressure at Sakarya, 2018 and Omsk, 2019. However, at higher leaf rust infection pressure at Omsk in 2017 and 2018, Almaty in 2019, there was a clear advantage for the germplasm possessing major genes. High level of stem rust infection in Omsk in 2019 confirmed effectiveness of the Sr31/Lr26 gene. A set of 33 genotypes was selected combining resistance to leaf and stem rust with superior agronomic performance. [ABSTRACT FROM AUTHOR]

Rust disease was observed on populations of Suaeda californica near Morro Bay, California. The pathogen was identified as a species of Uromyces based on teliospore and urediniospore morphology and nuc 28S rDNA sequence analysis. The isolate was compared with previously described species of Uromyces that infect members of Chenopodiaceae, prompting a taxonomic reevaluation of Uromyces species on Suaeda. Herein, Uromyces rebeccae is described. It can be differentiated from the closely related U. chenopodii (syn.: Aecidium chenopodii-fruticosi; U. giganteus) based on host range, teliospore morphology, and 28S sequence data. The new combination, Uromyces chenopodii-fruticosi, is made for Aecidium chenopodii-fruticosi, the oldest name for Eurasian Suaeda rust. Finally, it was determined that U. giganteus likely does not occur in the United States and that the rust of S. taxifolia in the United States likely comprises a third, yet unnamed taxon, different from both U. rebeccae and U. chenopodii-fruticosi. This is the first record of a rust fungus on S. californica. An identification key for Uromyces species reported on Chenopodiaceae is provided. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Production is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Twenty-three wheat genotypes were evaluated for stripe and leaf rusts, caused by Puccinia striiformis f. sp. tritici and Puccinia triticina f. sp. tritici, respectively, at seedling and adult stages under greenhouses and field conditions during the 2019/2020 and 2020/2021 growing seasons. The race analysis revealed that 250E254 and TTTST races for stripe and leaf rusts, respectively were the most aggressive. Eight wheat genotypes (Misr-3, Misr-4, Giza-171, Gemmeiza-12, Lr34/Yr18, Lr37/Yr17, Lr46/Yr29, and Lr67/Yr46) were resistant to stripe and leaf rusts at seedling and adult stages. This result was confirmed by identifying the resistance genes: Lr34/Yr18, Lr37/Yr17, Lr46/Yr29, and Lr67/Yr46 in these genotypes showing their role in the resistance. Sids-14 and Shandweel-1 genotypes were susceptible to stripe and leaf rusts. Twelve crosses between the two new susceptible wheat genotypes and the three slow rusting genes (Lr34/Yr18, Lr37/Yr17, and Lr67/Yr46) were conducted. The frequency distribution of disease severity (%) in F2 plants of the twelve crosses was ranged from 0 to 80%. Resistant F2 plants were selected and the resistance genes were detected. This study is important for introducing new active resistance genes into the breeding programs and preserving diversity among recently released wheat genotypes.

Copyright of Egyptian Journal of Agronomy is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work aims at understanding the effect of microstructures (coarse, medium and fine ferrite–pearlite, martensite and tempered martensite) of a reinforced (rebar) steel developed by various heat-treatments (furnace cooling, air-cooling, force air-cooling, quenching, and tempering, respectively) on its corrosion behavior in freely aerated 3.5% NaCl + 3.5% FeCl3 solution. The impressed current technique was used for forcing corrosion of the rebar, which was embedded in concrete coupon, so that correlation could be drawn between microstructure and corrosion behavior in short duration. Corrosion susceptibility increased from force air-cooled–quenched–air cooled–furnace cooled–tempered steels. The crack formation in the concrete was directly related to the rust composition and thickness, presence of crack in the rust, alpha/gamma* ratio and critical corrosion amount. [ABSTRACT FROM AUTHOR]

Climate change is leading to increased occurrence of and yield losses to wheat diseases. Managing these diseases by introducing new, effective and diverse resistance genes into cultivars represents an important component of sustainable wheat production. In 2016 and 2017 a set of primary hexaploid synthetic wheat was studied under high disease pressure: powdery mildew, leaf and stem rust in Omsk; Septoria tritici and S. nodorum in Moscow. A total of 28 synthetics (19 CIMMYT synthetics and 9 Japanese synthetics) were selected as having combined resistance to at least two diseases in both years of testing. Two synthetics (entries 13 and 18) originating from crosses between winter durum wheat Ukrainka odesskaya-1530.94 and various Aegilopes taushii accessions, and four synthetics (entries 20, 21, 23 and 24) from cross between Canadian durum wheat Langdon and Ae. taushii were resistant to all four pathogens. Pathological and molecular markers evaluation of resistance suggests presence of new genes and diverse types of resistance. The novel genetic sources of disease resistance identified in this study can be successfully utilized in wheat breeding. • Primary synthetics demonstrated resistance to several important diseases. • Six entries were resistant to powdery mildew, leaf/stem rust, Septoria in 2016/17. • Resistance type varied from immunity to slow disease development. • The resistance is controlled by both known and possibly new genes. • The novel genetic sources of resistance are valuable for wheat breeding. [ABSTRACT FROM AUTHOR]

Production and productivity of wheat crop is hampered by the biotic and abiotic stresses putting the world food security at risk. Among the biotic stresses, rusts are the major threat throughout the wheat growing areas in the world whereas Karnal bunt, powdery mildew, Fusarium head blight and loose smut are of minor importance. These diseases severely affect the yield and quality of wheat grain. Till date these diseases have been contained by the use of host resistance alongwith the chemical fungicides. However, the host resistance is overcome with the evolution of new virulent pathotypes. Deployment of diverse and durable sources of resistance in breeding programmes is the most economic and effective means of reducing yield losses caused by these diseases.With an aim to identify novel sources of resistance to these pathogens, 247 Indian wheat accessions were evaluated for multiple disease resistance at six different hot spots in order to identify potentially new sources of resistance. Of the 247 accessions of wheat, 14 accessions highly resistant to stripe rust, 142 for Leaf rust and 146 for stem rustwere identified. Thirty-two accessions were found resistant to all the three rusts. Thirty accessions showed immune reaction to powdery mildew and 61 were recorded resistant. Data obtained from spot blotch experiment revealed one accession immune to spot blotch infection while two accessions were recorded resistant with 10% infection. Karnal bunt (KB) resistance (infection level < 5) was observed in 186 lines. Out of 247 lines 69 and 93 accessions were found to have resistance against spot blotch and loose smut respectively. Accession No. IC128643 was found to be the most promising accession that has resistance against three rusts, powdery mildew, Karnal bunt, loose smut and spot blotch. Accession no. IC36900, IC397999 and IC416249 showed resistance against three rusts, powdery mildew, Karnal bunt and loose smut while accession no. IC415971 and IC415977 showed resistance against three rusts, powdery mildew, spot blotch and loose smut. The resistant germplasm lines, identified in this study can be used for introgressing resistance to high yielding backgrounds and are expected to contribute towards food security at national and global levels. [ABSTRACT FROM AUTHOR]

Due to low requirements for fertilizers and pesticides, garlic is a valuable crop in organic systems, although production may be hampered by diverse pathogens. In recent years, garlic rust (Puccinia spp.) has been increasingly present in our agro-ecological climate, developing into a significant problem for garlic production. The aim of the study was twofold: i) to monitor winter garlic rust rate in organic and in conventional production, and ii) to monitor genotype sensitivity to the pathogen in both production systems. Trials were conducted in 2012/2013 in Bački Petrovac, Serbia at the Institute of Field and Vegetable Crops in Novi Sad, and included 30 genotypes planted in organic and conventional field, simultaneously. Disease severity was evaluated visually, using a scoring system between zero and five. Overall average infection intensity score in conventional plots was 1.18, and in organic plots 0.79. There was no statistically significant difference between infection intensity in conventional versus organic plots. Nevertheless, reactions of certain genotypes to the causal agents of rust differed across organic and conventional plots ranging from no apparent infection symptoms in organic to severe symptoms in conventional plots.

Summary: Wheat is one of the primary staple foods throughout the planet. Significant yield gains in wheat production over the past 40 years have resulted in a steady balance of supply versus demand. However, predicted global population growth rates and dietary changes mean that substantial yield gains over the next several decades will be needed to meet this escalating demand. A key component to meeting this challenge is better management of fungal incited diseases, which can be responsible for 15%–20% yield losses per annum. Prominent diseases of wheat that currently contribute to these losses include the rusts, blotches and head blight/scab. Other recently emerged or relatively unnoticed diseases, such as wheat blast and spot blotch, respectively, also threaten grain production. This review seeks to provide an overview of the impact, distribution and management strategies of these diseases. In addition, the biology of the pathogens and the molecular basis of their interaction with wheat are discussed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Production is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Monitoring of wheat crop, pre and post harvest, was done for recording incidence of various diseases in Punjab state during the period 2013-14 to 2015-16. The data indicated a change in virulence of stripe rust pathogen among the pre harvest diseases, whereas, among the post harvest diseases, Karnal bunt, a minor disease earlier, has become a matter of concern as its incidence has increased over the years (highest 2.20% in 2014-15). The trend is considered mainly due to prevalence of favourable environmental conditions during the most vulnerable growth stage of the crop. [ABSTRACT FROM AUTHOR]

Genetic resistance against biotic stress is a major goal in many wheat breeding programs. However, modern wheat cultivars have a limited genetic variation for disease and pest resistance and there is always a possibility of the evolution of new diseases and pests to overcome previously identified resistance genes. A total of 125 synthetic hexaploid wheats (SHWs; 2n = 6x = 42, AABBDD, Triticum aestivum L.) were characterized for resistance to fungal pathogens that cause wheat rusts (leaf; Puccinia triticina, stem; P. graminis f.sp. tritici, and stripe; P. striiformis f.sp. tritici) and crown rot (Fusarium spp.); cereal cyst nematode (Heterodera spp.); and Hessian fly (Mayetiola destructor). A wide range of genetic variation was observed among SHWs for multiple (two to five) biotic stresses and 17 SHWs that were resistant to more than two stresses. The genomic regions and potential candidate genes conferring resistance to these biotic stresses were identified from a genome-wide association study (GWAS). This GWAS study identified 124 significant marker-trait associations (MTAs) for multiple biotic stresses and 33 of these were found within genes. Furthermore, 16 of the 33 MTAs present within genes had annotations suggesting their potential role in disease resistance. These results will be valuable for pyramiding novel genes/genomic regions conferring resistance to multiple biotic stresses from SHWs into elite bread wheat cultivars and providing further insights on a wide range of stress resistance in wheat.

Rusts are one of the most important fungal diseases, the known target sites have already developed serious resistance to the main existing classifications of fungicides. In order to discover novel fungicides with a promising activity on rusts, twenty new substituted difluoromethylpyrimidinamine derivatives were designed and synthesized with the aid of the intermediate derivatization methods starting from ethyl 4,4-difluoro-3-oxobutanoate that is the common raw material in some newly launched important succinate dehydrogenase inhibitor (SDHI) fungicides. Their structures were identified by 1 H NMR, 13 C NMR, 19 F NMR, IR, elemental analyses and HRMS. All the compounds were screened for in vivo fungicidal activity against southern corn rust (SCR). The preliminary bioassay results indicated that 5-chloro-6-(difluoromethyl)- N -(2-(6-(3-(trifluoromethyl)phenoxy)pyridin-3-yl)ethyl)pyrimidin-4-amine (compound J , R 1 = CHF 2 , Alk = CH 2 CH 2 , Rn = 3-CF 3 ) is the optimal structure with desired fungicidal activity against SCR (EC 50 = 2.16 mg/L), significantly higher than commercial fungicides diflumetorim (EC 50 = 53.26 mg/L) and propiconazole (EC 50 = 3.92 mg/L). The structure–activity relationship of the synthesized compounds was discussed as well. This study also demonstrated that difluoromethylpyrimidinamine derivatives can be further utilized as a promising antifungal agent to control rust. Further synthesis and structure optimization studies are currently in progress. [ABSTRACT FROM AUTHOR]

Rusts (Fungi, Basidiomycota, Pucciniomycotina, Pucciniomycetes, Pucciniales) are one of the most important causal agents of diseases and they are infecting many plants including cereals and field crops, vegetables, trees and many ornamentals. They have been studied for a long time and have economic importance among the plant diseases caused by agents of different species of fungi. In Europe, thirteen rust genera have been reported, of which the genus Gymnosporangium is the second largest after genus Phragmidium. The most significant fruit tree rust pathogen is the genus Gymnosporangium. The literature review shows quite limited scientific information about this genus and its species. Studies have mainly focused on some stages of the pathogen development cycle, which are significant for the spread of diseases -- uredo and teleito stages. Special attention of the review was paid to European pear rust (caused by G. sabinae (Dicks.) G. Winter), the distribution of which has increased during the last ten years, especially in organic pear orchards. Currently there is a limited number of scientific publications about European pear rust, and they are mainly based only on observations in vitro without trials in the field, despite the fact that it has become one of the most devastating diseases. Therefore, the presented review analyses the rust exploration history, diversity and distribution of species, life cycle, development biology and plant protection issues. [ABSTRACT FROM AUTHOR]

Colecciones de plantas con síntomas de hongos royas (Uredinales, Basidiomycota) realizadas en los últimos años en los departamentos de Amazonas, Antioquia, Caldas, Cundinamarca, Tolima y Valle del Cauca han sido estudiadas y depositadas en el Museo Micológico de la Universidad Nacional de Colombia, Sede Medellín (MMUNM). Entre las novedades encontradas, se registran por primera vez para Colombia las royas: Puccinia investita, Sphenospora pallida, Crossopsora piperis, Uredo psychotriicola y Pucciniosira solani. Se adiciona la familia botánica Dioscoreaceae para la Biota de Uredinales colombianos. Se hace la corrección del nombre anamórfico Uredo parthenii publicado para Colombia en 2003, por el nombre teliomorfico válido Puccinia schileana. Son registrados seis nuevos hospedantes parasitados por royas en Colombia, entre estos reviste importancia la colección sobre Origanum vulgare L. una planta aromática y medicinal cultivada mundialmente.Plant collections with symptoms of rusts fungi (Uredinales, Basidiomycota) made during recent years in provinces of Amazonas, Antioquia, Caldas, Cundinamarca, Tolima and Valle del Cauca have been studied and deposited in Museo Micológico of Universidad Nacional de Colombia, Sede Medellín (MMUNM). The rusts species Puccinia investita, Sphenospora pallida, Crossopsora piperis, Uredo psychotriicola and Pucciniosira solani are new records for Colombia. A first record for this country of rust fungi in plants of family Dioscoreaceae has been also made. The anamorphic name Uredo parthenii published in 2003 in Colombia, has been corrected by the valid teleomorph Puccinia schileana. Finally, six new hosts parasitized by rusts are recorded, including Origanum vulgare L. a world-wide important aromatic and medicinal plant.

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. [ABSTRACT FROM AUTHOR]

A translocation from Aegilops ventricosa carrying genes Yr17, Lr37 and Sr38 was verified in cultivars Hussar, Eureka, Torfrida, Renan, Rendezvous, Rapier and Brigadier by the molecular marker SCARSC-Y15. Of the cultivars recently registered in the Czech Republic, only the western European cultivars Corsaire, Apache, Complet and Bill possessed the translocation carrying Yr17, Lr37 and Sr38. Cultivars Corsaire, Apache, Bill and Complet were highly or medium resistant to yellow rust and leaf rust in 1999-2001 field trials at Prague-Ruzyně, although virulence to Yr17 was found in the 2001 virulence survey also in the Czech Republic. Cultivars Corsaire, Apache and Bill displayed an above average resistance to stem rust, whereas Complet was susceptible.

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. [ABSTRACT FROM AUTHOR]

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.

A new wheat variety (Millat 2011), high yielding and disease resistant was developed by hybridization between two wheat genotypes Chenab-2000 and Inqalab-91 at Wheat Research Institute, Faisalabad, Pakistan. F2 to F6 generations of this cross were advanced by modified bulk pedigree method from 1999 to 2005. The plant type of Millat-2011 is semi erect with 100-115 cm height and straw color is yellow .Its flag leaf attitude is semi erect and auricle color is white. This variety has tapering head shape with 10-11 cm length having 16-18 spikelets per spike. The heads of Millat 2011 emerges from flag leaf between 100-110 days and matures within 142-150 days. It has high tillering capacity (490 tillers/m2). The grain is ovate, medium and amber in color. Its grain yield potential is 6358 kg/ha and average yield is 4091-4268 kg/ha in different agro-ecological zones. Millat 2011 generally produced higher yield in late planting than check varieties. The quality parameters are also comparable with the existing varieties. The 1000 kernel weight is 32.00 to 45.69g, seed is in amber colour and contains 12.33 to 15.17% protein and 66.59 to 71.50% flour. It has good chapatti making quality. New wheat variety Millat 2011 is moderately resistant to Ug 99 race of stem rust and also resistant to prevailing races of leaf and yellow rusts. The variety is tolerant to lodging and was approved by Punjab Seed Council for cultivation in Punjab province of Pakistan. [ABSTRACT FROM AUTHOR]

Leaf rust caused by Puccinia triticina is the most important disease among the three rusts of wheat in Bangladesh. The disease occurs in all wheat growing areas of the country with varying degrees of severity. Stem rust caused by P. graminis f.sp. tritici was last observed during the mid 1980s, while yellow rust caused by P. striiformis f.sp. tritici occurs occasionally in the north-western region, where a relatively cooler climate prevails during the winter months. None of the rusts has yet reached an epidemic level, but damaging epidemics may occur in future, particularly if a virulent race develops or is introduced. The genes conferring rust resistance in the breeding lines and wheat varieties released in Bangladesh were investigated at CIMMYT-Mexico and DWR-India. The resistance genes Lr1, Lr3, Lr10, Lr13, Lr23 and Lr26, Sr2, Sr5, Sr7b, Sr8b, Sr9b, Sr11 and Sr31; and Yr2KS and Yr9 were found. An adult plant slow rusting resistance gene Lr34 was also identified in some of the breeding lines and varieties based on the presence of clear leaf tip necrosis under field conditions. Considering the possible risk of migration of the devastating Ug99 race of stem rust into the Indo-Pak subcontinent, the Bangladeshi wheat lines and cultivars are being regularly sent to KARI in Kenya for testing their resistance against this race. The resistant lines have been included in multi-location yield trials and multiplied for future use in order to mitigate the threat of Ug99. The resistant lines have also been included in crossing schemes to develop genetic diversity of rust resistance.

Medicinal plants are infected by fungal diseases. A four years survey indicated that, there are various fungal infections in roots and shoots of several medicinal plants that grown in Isfahan. Lavender (Lavandula angustifolia), rosemarry (Rosmarinus officinalis) and viper's bugloss (Borago officinalis) plants were infected by Fusarium oxysporum and F. solani on roots, showing wilting and eventually plants death, though, F. culmorum was also isolated, but without pathogenicity on these hosts. The sage plants (Salvia officinalis) were also infected by F. solani considerably. Burdock plants (Aractium lappal) were infected not only by F.oxysporum and F.solani, but also Verticillium dahliae and V. alboatrum and common balm (Melissa officinalisl) by F. solani. They were also simultaneously infected by Rhizoctonia solani. The aerial infections were mainly powdery mildews, downy mildews and rust. The naked seed pumpkin (Cucurbita pepo var. sterica) and common pumpkin (Cucurbita popo) were infected by Erysiphe cichoracearum and Sphaerotheca fuliginea., Johns-worth hypericum (Hypericum perforatum), by Leveillula guttiferatum and E. hypersici., estragon (Artemisia dracunculus) by E. artemisiae., bitter sweet (Solanum dulcamara) by E. beceleate., flixweld (Descurainia sophia) by E. communiis., marsh mallows (Althaea officinalis and Malva silvestris) by L. malvacearum., licoric (Glycyrrhiza globra) by L. leguminosar, dill (Anethum graveolens) and coriander (Coriandrum sativum) by L. umbelleferatum., downy mildews were observed on spinach (Spinacia oleracea) Peronospora farinosa, summer savory (Satureia hortensis) P. Lamii and waybread (Plantago major) P. alta. There was also rust diseases on medicinal plants including, estragon (Puccinia absinthi), wild thyme (Thymus serpllum) P. serpylli, P. mentha and also on pudding grass (Mentha pulegium) and peppermint (Mentha piperita) P. mentha. white rusts, Albugo candida, were also observed on some of the medicinal plants including, flixweld and mother's heart (Capsella bursa-pastoris). The two species of Verticillium dahha and V. albo- atrum with lower frequency on some of the medicinal plants especially on lavander, rosemarry, pudding gross, pepper mint, castor (Ricinus communis) was found and there were typical symptoms on pepper mint. Rhizoctionia solani is an another fungal infecting agents, causing dry canker on roots and underground stems of some of the medicinal plants in this area. [ABSTRACT FROM AUTHOR]

Abstract: Three rusts, Puccinia nassellae, Uromyces pencanus, and Puccinia graminella, are being studied as potential biological control agents for Nassella neesiana (Chilean needle grass) in Australia and New Zealand. An understanding of the life cycle of a pathogen is desirable before its release as a biocontrol agent is considered, to enable the assessment of the risks involved in such a release. Field observations and experiments have been carried out to elucidate the life cycles of these three pathogens. Puccinia nassellae cycles as urediniospores and produces dormant teliospores. Dormancy of teliospores has been broken through manipulation in the laboratory, but resulting basidiospores have failed to infect N. neesiana plants under the conditions tested. Uromyces pencanus cycles as urediniospores and its telia appear to have lost the capacity to produce basidiospores. Aecia have been reported for this rust in the literature. However, evidence is provided that these aecia in fact belong to the life cycle of P. graminella. Puccinia graminella produces only aecia and telia. The aeciospores have been shown to be repetitive (aecidioid urediniospores). Teliospores germinate directly without a dormant phase, but resulting basidiospores failed to infect N. neesiana plants under the conditions tested. The role of teliospores in the life cycle of all three rusts remains unknown. Although the autoecious nature of their life cycles has not been proven experimentally, neither is there any evidence that they are heteroecious. Practical and theoretical implications of these findings are discussed. [Copyright &y& Elsevier]

Copyright of Acta Scientiarum Polonorum. Agricultura is the property of University of Technology & Life Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Partial ß-tubulin 1 sequence data were obtained for 80 taxa of Pucciniaceae, with hosts from 33 angiosperm families, covering all major ordinal groups in the Angiosperm Phylogeny Group classification. As in previous studies, most species of Puccinia and Uromyces fell into two main clades (I and II), with P. glechomatis and P. psidii excluded from Pucciniaceae. Results suggest two processes; a coevolution of and hosts in each clade, as well as associated frequent jumps to ecologically close, but taxonomically distant, hosts. Clade I contained all rusts on Cyperaceae and Juncaceae, and most rusts on host orders from rosids to euasterids II. Clade II contained all rusts on Poaceae, and most on host orders from monocots to core eudicots. In both main clades, several well-supported subclades were identified. The grouping in clade I, subclade E of rusts of Cyperaceae and Asteraceae and, in particular, of an Australian isolate of P. dioicae with rusts on Australian families of Asterales, suggested a local radiation, and supported the coevolutionary relationship between rusts on these two families seen with a different range of asteraceous rusts in the Northern Hemisphere. In clade I, two clades contained only rusts of Asteraceae and Fabaceae, respectively, and in clade II, subclade F contained only rusts of pooid hosts. Rusts on non-pooid hosts were separated from them in subclade G. Other subclades contained a range of rusts on distantly related angiosperm families. Urediniospore morphology was often, but not always, correlated with the molecular phylogeny. Most rusts with urediniospores having few (1–5) equatorial germ pores were in clade I, whereas most with spores having several (5–14) scattered pores were in clade II. The distribution of telial host families on the ß-tubulin rust phylogeny was not random. Aecial hosts of heteroecious rusts played an important role in the evolutionary process. Possible examples of host jumps were seen in rusts on Geraniaceae, Polygonaceae, and Apiaceae. Despite such jumps obscuring past host associations, possible ancestral hosts were identified by the pattern of host distribution at higher taxonomic levels along the ß-tubulin phylogeny. Results suggest that clade I diverged with Cyperaceae, Juncaceae, and the more advanced core eudicot orders (rosids and asterids), whereas clade II diversified with earlier angiosperm groups, such as monocots, Poaceae, and Ranunculales. Qualified support was given to the hypothesis that rusts can reveal taxonomic relationships between their hosts, at genus, family, and ordinal levels. [Copyright &y& Elsevier]

Hydrogen sulfide reacts with the corrosion products (Fe2O3) in oil tanks to form iron sulfides. The oxidation and released heat of iron sulfides can lead to spontaneous combustion of iron sulfides and fire of oil tanks. In this article, the simulating production process of iron sulfides in oil tanks and the effects of flow rate of hydrogen sulfide, environmental temperature and setting time on the quantities and types of iron sulfides are studied. [ABSTRACT FROM AUTHOR]

Knowing pests and diseases that may cause injuries and are likely to affect plant health and quality is critical to minimizing the gap between attainable yield and actual yield. In this paper, we highlight concepts and strategies aimed at controlling major biotic constraints affecting wheat in intensive production systems and present emerging challenges, with a special attention to the developing world. Disease epidemics result from the combination of inoculum, favorable environment, and host susceptibility. Changes in cropping systems as a result of adoption of conservation agriculture may have serious implications. Necrotrophic pathogens such as those responsible for tan spot or septorias are likely to emerge, and Fusarium head blight may increase. However, resistance breeding combined with rotations, timely sowing, and irrigation or even fungicide utilization, if affordable, are part of integrated crop management practices that can minimize losses. In South Asia, the effect of spot blotch, a devastating foliar disease caused by Cochliobolus sativus, can be minimized by reducing physiological stress through timely sowing and adequate use of fertilizers, which demonstrates the complex relationships among crop physiology, disease resistance, and yield. Although some root rots that induce premature death of tillers in cooler high-yielding humid environments can be important, the dryland crown rot ( Fusarium spp.), common root rot ( C. sativus), and the cereal nematode ( Heterodera spp. and Pratylenchus spp.) should not be ignored. These are all known to be much more damaging under suboptimal moisture (rainfed or supplementary irrigation), particularly where plant growth is stressed. Climate change is likely to modify the wheat disease spectrum in some regions, and pathogens or pests considered unimportant today may turn out to be potential new threats in future. [ABSTRACT FROM AUTHOR]

Cellular interaction of the basidiomycete Tuberculina persicina with the haploid stages of two rusts Puccinia silvatica and Tranzschelia pruni-spinosae was analyzed by serial-section electron microscopy of chemically fixed samples and samples subjected to high-pressure freezing and freeze substitution. Tuberculina persicina is a contact parasite, forming neither haustoria nor other intracellular structures. However, at contact areas between T. persicina and its hosts, distinct interfungal interactions are present. At the beginning, a hyphal cell of T. persicina invades the host cell wall with a protuberance and the cell walls of both protuberance and host cell dissolve at the point of contact. Thus, the plasma membranes of the two organisms contact and fuse to form a pore that enlarges to a final diameter of approximately 1 µm. The membrane of the fusion pore is continuous with the plasma membranes of both cells, and Tuberculina nuclei and other organelles are transferred to the rust cells. Phylogenetic and functional aspects of this curious basidiomycetous interfungal interaction are discussed, and a hypothesis of the evolutionary derivation of the Tuberculina mycoparasitism from a sexual interaction is presented. [ABSTRACT FROM AUTHOR]

A multiplex Polymerase Chain Reaction (PCR) assay was developed to detect and quantify four fungal foliar pathogens in wheat. For Septoria tritici (leaf blotch) and Stagonospora nodorum (leaf and glume blotch), the β-tubulin gene was used as the target region. Diagnostic targets for Puccinia striiformis (stripe or yellow rust) and P. recondita (brown rust) were obtained from PCR products amplified with β-tubulin primer sequences. Final primer sets were designed and selected after being tested against several fungi, and against DNA of infected and healthy wheat leaves. For detection of the four pathogens, PCR products of different sizes were amplified simultaneously, whereas no products were generated from wheat DNA or other non-target fungi tested. The presence of each of the diseases was wheat tissue- and cultivar specific. Using real-time PCR measurements with the fluorescent dye SYBR Green I, PCR-amplified products could be quantified individually, by reference to a standard curve generated by adding known amounts of target DNA. Infection levels for each of the diseases were measured in the flag leaf of 19 cultivars at Growth Stage (GS) 60–64 in both 1998 and 1999. The infection levels for the cultivars were ranked, and showed, with a few exceptions, a good correlation with the NIAB Recommended List for winter wheat, which is based on visual assessment of symptoms. With PCR, the presence of the different pathogens was accurately diagnosed and quantification of pre-symptomatic infection levels was possible. Although sampling and DNA detection methods need further optimisation, the results show that multiplex PCR and quantitative real-time PCR assays can be used in resistance screening to measure the interaction between different pathogens and their hosts at different growth stages, and in specific tissues. This should enable an earlier identification of specific resistance mechanisms in both early-stage breeding material and field trials. [ABSTRACT FROM AUTHOR]

A collection comprising 157 Aegilops geniculata accessionsoriginating from different ecogeographical regions was established atENSA-INRA, Montpellier. The accessions were studied for physiologicaltraits related to drought and heat stress and screened for resistance tobarley yellow dwarf virus (BYDV) and rusts. Some accessions were alsotested for resistance to Hessian fly and cereal cyst nematodes (CCN). The study allowed to distinguish different adaptive strategies to theclimatic constraints encountered by Aegilops populations in theirregion of origin. They led to significant differences in biomass and grainproduction and should be taken into account in the utilisation of Ae.geniculata germplasm in wheat breeding programs. Two accessions withresistance to BYDV were found. Both originated from South of France. Theinterest of Ae. geniculata as a source of rust resistance was confirmedand accessions with resistance to the three rusts were identified. Highresistance against populations of Heterodera avenae and H.latipons was found in accessions from Spain, Bulgaria, Jordan and Tunisia.Sources of resistance to Hessian fly were also identified. [ABSTRACT FROM AUTHOR]