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Puccinia striiformis Westend. f. sp. tritici Eriksson (Pst), the causal agent of stripe rust, is known as an important and destructive pathogen that causes critical wheat losses in many parts of the world. Employing effective resistant genotypes is a safe and operative strategy to combat the disease. Iran is located in the Fertile Crescent, the co-epicentre of wheat and its biotic stresses. Iranian wheat landraces may carry important sources of resistance against rust diseases. Adult plant reactions of 467 Iranian wheat landraces to stripe rust were studied in two cropping seasons in Fars province. One hundred and six landraces showed acceptable levels of resistance and were selected for further seedling and molecular studies based on their lower infection type, coefficient of infection (CI) and average coefficient of infection (ACI). The presence of Yr4, Yr10, Yr24 and Yr32 resistance genes were postulated using 10 different Pst isolates including PstS10, PstS7, PstS3, PstS2+V27, PstS11, PstS8, PstS13, PstS6, PstS0 and Me2018 under greenhouse conditions. Field and greenhouse reactions of near-isogenic lines reconfirmed the presence of the studied Yr resistance genes in 20 genotypes. Moreover, Xcfb3530150, Xpsp3000, Xgwm11, and Xwmc198 SSR markers were employed to identify and validate the presence of the above corresponding genes. The presence of Yr4, Yr10, Yr24 and Yr32 resistance genes in five (1.07%), 10 (2.14%), five (1.07%) and seven (1.5%) experimental landraces were confirmed, respectively. Six genotypes are harbouring more than one resistance gene. These effective resistance sources can be employed in national and international breeding programs. [ABSTRACT FROM AUTHOR]

Stripe rust (Puccinia striiformis f. sp. tritici (Pst)) is one of the most devastating fungal diseases of durum wheat (Triticum turgidum L. var. durum Desf.). Races of Pst with new virulence combinations are emerging more regularly on wheat-growing continents, which challenges wheat breeding for resistance. This study aimed to identify and characterize resistance to Pst races based on a genome-wide association study. GWAS is an approach to analyze the associations between a genome-wide set of single-nucleotide polymorphisms (SNPs) and target phenotypic traits. A total of 139 durum wheat accessions from Iran were evaluated at the seedling stage against isolates Pstv-37 and Pstv-40 of Pst and then genotyped using a 15K SNP chip. In total, 230 significant associations were identified across 14 chromosomes, of which 30 were associated with resistance to both isolates. Furthermore, 17 durum wheat landraces showed an immune response against both Pst isolates. The SNP markers and resistant accessions identified in this study may be useful in programs breeding durum wheat for stripe rust resistance. [ABSTRACT FROM AUTHOR]

Barley yellow rust is one of the important barley diseases in the world. However, the importance of this disease has recently increased in Iran. The main aim of the present study was to identify the sources of resistance to this disease in a collection of Iranian barley genotypes provided from the National Plant Gene Bank of Iran (NPGBI). For this purpose, a set of 128 accessions of the north and northwest regions of Iran were assessed in terms of resistance components such as disease severity, infection type and coefficient of infection under natural incidence of the disease in the field of Ardebil Research Station as a hotspot region for barley yellow rust during 2019-2022 cropping seasons. The results indicated a considerable genetic diversity among the tested genetic materials in response to this disease. A moderate correlation was observed between the evaluations of different years. The accessions were separated into five groups using cluster analysis, and the second group with 41 members with the lowest infection coefficient average was identified as the most resistant group. The results of this research showed the high capacity of the collection to identify sources of resistance to barley yellow rust disease. The identified resistant germplasm can be used in breeding programs for resistance to this disease. [ABSTRACT FROM AUTHOR]

In the present study we collected 12 clones of garlic from different geographical origin in Iran. The clones were sown in a field trial under natural infection of the rust fungus during two consecutive years. After 210 days, the reactions of the clones to the disease as well as the morphological features of the clones were evaluated. The results of analysis of variance on morphological traits showed a significant difference among the clones in terms of bulb weight, mean clove weight, number of bulb skin, number of cloves in the bulb, leaf temperature and the percentage of clove dry weight, and nutrient uptake for N,P,K, Mn and Zn. The results showed a positive and significant correlation between the leaf temperature, photosynthesis, nitrogen and manganese uptake and percentage of leaf infection at 1% probability level. The results of the infection frequency showed that the clones 'Gilvan1' and 'Lalejin' had the lowest percentage of infection and were identified as resistant clones to the rust disease. The results also showed that garlic clones reacted differently to the rust fungus and are separated into resistant, semi resistant, semisusceptible and susceptible clones. [ABSTRACT FROM AUTHOR]

From 2009 to 2018, a total of 80 wheat crops were studied at plot and regional scales to predict stripe rust epidemics based on influential climatic indicators in Kermanshah province, Iran. Disease onset time and epidemic intensity varied spatially and temporarily. The disease epidemic variable was classified as having experienced nonepidemic, moderate or severe epidemics to be used for statistical analysis. Principal component analysis (PCA) was used to identify climatic variables associated with occurrence and intensity of stripe rust epidemics. Two principal factors accounting for 70% of the total variance indicated association of stripe rust epidemic occurrence with the number of icy days with minimum temperatures below 0°C (for subtropical regions) and below −10°C (for cool temperate and semi-arid regions). Disease epidemic intensity was linked to the number of rainy days, the number of days with minimum temperatures within the range of 7−8°C and relative humidity (RH) above 60%, and the number of periods involving consecutive days with minimum temperature within the range of 6−9°C and RH% > 60% during a 240-day period, from September 23 to May 21. Among mean monthly minimum temperatures and maximum relative humidity examined, mean maximum relative humidity for Aban (from October 23 to November 21) and mean minimum temperature for Esfand (from February 20 to March 20) indicated higher contributions to stripe rust epidemic development. Confirming PCA results, a multivariate logit ordinal model was developed to predict severe disease epidemics. The findings of this study improved our understanding of the combined interactions between air temperature, relative humidity, rainfall, and wheat stripe rust development over a three-season period of autumn-winter-spring. [ABSTRACT FROM AUTHOR]

Many physiological races ofPuccinia striiformisf. sp.triticiwhich cause stripe rust in wheat can be determined in different parts of the world. The emergence of new races with different pathogenicity which happens very quickly breaks cultivars resistant and cause disease. Therefore, breeding cultivar for resistance to different pathogenic races should be continued. In this research, pathogenicity of two isolates collected from two regions of Iran were determined by using wheat yellow rust differential lines, which indicated race 70E50A+ and 6E18A+  The responses of 30 wheat genotypes were separately evaluated in the forms of randomized complete block design with three replicates in the seedling stage under greenhouse condition. The components of resistance including latent period and infection type were recorded. Results indicated genotypes were evaluated in terms of both traits and were significant at 1% level. Also, the results from pathogenicity study indicated of effective gene/s includedYr1, Yr2+, Yr3, Yr4, Yr5, Yr10, Yr15, Yr24, Yr26, YrSP, YrND, YrSDandYrSU. From the genotypes studied in the greenhouse condition, 39% of the genotypes showed complete resistance to both races. Probably, resistance genes,Yr32andYrCV, or the other unknown genes which are types of seedling resistance are either alone or in combination of one another cause strength in resistant genotypes. [ABSTRACT FROM PUBLISHER]

Wheat yellow (stripe) rust disease is one of the important and prevalent diseases of wheat in the world. In this study, 37 isolates of yellow rust diseased from most important wheat-growing areas in Iran has been collected, and the genetic of pathogenesis and race analysis as well as abundance per cent of the disease for genes under study with using 45 differential and isogenic lines together with susceptible Bolani were applied. The experimental materials with the spores of each isolate that were inoculated in the seedling stage separately and after 17 days scored by McNeal et al. method. Also the physiologic races responsible for the disease determined according to Johnson and his colleagues method. The results showed that the race 166E254A + Yr27+ with 62.50% of pathogenesis was the most aggressive race from Torogh (Mashhad) 6, and the race 6E134A+ with 33.34% of pathogenesis factor was the weak race from Zarghan1. According to these results, for all the plants containing genesYr2,Yr6,Yr7,Yr9,Yr18,YrAvirulence was observed from all isolates. For the plants contained with genesYr1,Yr4,Yr5,Yr10,Yr15,YrSUwere effective against all isolates. GenesYr3,Yr24,YrSPwith low per cent of pathogenesis (2.7) and genesYr2,Yr6,Yr7,Yr9,Yr18,Yr4with high per cent (100) andYr17(97.3) have been identified. [ABSTRACT FROM AUTHOR]

Stripe rust of barley (Hordeum vulgareL.), caused byPuccinia striiformisf. sp.hordei, is a serious problem of barley production in many parts of the world. Monitoring of the pathogen virulence factors and their changes provides basic information for development of an early warning system to breeders and researchers. To monitor the regular virulence changes, trap nurseries comprising of 12 barley differential sets were planted at different parts of Iran in six consecutive years 2007–2012. When the infection and severity under natural infection on susceptible cultivar Afzal as the check was high, then the response of each line was assessed using modified Cobbs scale. Results revealed that no virulence was observed on plants with resistance genesrpsEm1, rpsEm2, rpsHF, Rps4, rpsVa1, rpsVa2 and rpsAst. Therefore, these genes were considered effective genes and can be used to pyramid with those for race-non-specific resistance genes to achieve more durable and highly effective resistance to stripe rust. The plants with the resistance genesrps2, Rps1.b, Rps3andrpsI5showed susceptible reaction and virulence was observed on them, thus their resistance genes were considered ineffective. [ABSTRACT FROM AUTHOR]

Race-specific resistance of barley (Hordeum vulgare L.) to the yellow rust caused by Puccinia striiformis f. sp. hordei, has been reported to be short-lived. Slow rusting resistance has been reported to last for a long time. Twenty Iranian barley cultivars along with resistant and susceptible controls were tested during the 2009-2010 and the 2010-2011 cropping seasons, in field plots at the Ardabil Agricultural Research Station (Iran). The cultivars were tested to identify slow rusting genotypes through epidemiological variables which included: final rust severity (FRS), apparent infection rate (r), relative area under the disease progress curve (rAUDPC), and coefficient of infection (CI). Moreover, differential sets were evaluated in order to determine effective and ineffective resistance genes to barley yellow rust. Results of the mean comparison of resistance parameters showed that cultivars Makouee, Dasht, Fasih, and Arass had low values of FRS, CI, r and rAUDPC compared with susceptible cultivars. The cultivars Walfajre, Abidar and Sahand which had moderate values of the different parameters, were marked as possessing a moderate level of slow rusting. The rest of the cultivars which had high values of different quantitative parameters, were grouped as having a low level of slow rusting or as susceptible. The correlation coefficient between different parameters of slow rusting was significantly high (r = 0.83-0.98). The virulence profile of the prevalent races revealed that rpsEm1, rpsEm2, rpsHF, Rps4, rpsVa1, rpsVa2, rpsAst were effective, and rps2, Rps1.b were ineffective resistance genes during the two year testing period. [ABSTRACT FROM AUTHOR]