To study the inheritance of STRIPE RUST resistance and to estimate the genetic components of resistance in wheat, F1, F2, BC1 and BC2 generations derived from a cross between MV17 as resistante and Bolani as susceptible parents together with parental lines were evaluated in a randomized complete block design (RCBD) with three replications in the greenhouse. The plant materials were inoculated with pathotypes 134E134A+ and 166E134A+ of STRIPE RUST in two different experiments. In all plants, resistance components including latent period (days from inoculation to first pustule eruption) and infection type were recorded after appearance of pustules on leaves. Generation mean analysis revealed that additive, dominance and epistasis (especially [j] and [l] components) play a major role in increasing and decreasing of latent period and infection type, respectively. In spite of significant additive effect, dominance gene effect was the most important component in controlling these two characteristics. Estimates of degree of dominance were very close to unity for the two concerned traits in response to both pathotypes which indicates a complete dominance resistance. Heritability ranged from moderate to high and number of segregating genes governing resistance ranged from 1 to 3.

Genetic control of infection type of STRIPE RUST was studied in a half-diallel design using six wheat varieties, Tiritea (a susceptible control), Tancred, Kotare, Otane, Karama, and Briscard. These varieties and their 15 F1 diallel hybrids were evaluated by three STRIPE RUST pathotypes, 7E18A-, 38E0A+, and 134E134A+. For each pathotype a randomized complete block design was conducted with 21 treatments. Data for infection type were analyzed on the basis of Morley Jones, Waiter and Morton, Griffing, and Hayman's graphical methods. Positive and negative degrees of dominance were observed for every pathotype, indicating the host-pathogen interaction. Analyses of variance showed the importance of both additive and dominance genetic effects in controlling the infection type of STRIPE RUST. However, the role of additive effects was more important than non-additive effects. Average of broad-sense and narrow-sense heritability estimates was 0.92 and 0.89, respectively. In the graphical analysis of Hayman, degree of dominance ranged from partial dominance to overdominance depending on the pathotype. Briscard, in all pathotypes, Karama in 7E18A- and 38E0A+and Kotare in 134E134A+, had mainly recessive genes. Significant negative geperal combining abilities(more resistance)were also obtained for Kotare in 7E18A-, for Briscard in 38E0A+,and for Briscard, Karama, and Kotare in 134E134A+.In conclusion, regarding the high heritability of infection type, it is possible to use the above mentioned varieties in breeding programs in order to reduce the infection type of STRIPE RUST in wheat      

STRIPE RUST is one of the most important fungal diseases of wheat that has been reported in all continents and more than 60 countries in the world. Wild emmer wheat, Triticum dicoccoides, the tetraploid progenitor of cultivated wheat, has proven to be a valuable source of novel STRIPE RUST resistance genes for wheat breeding. G25accession of this species has Yr15 gene that confers resistance to 31 STRIPE RUST races and pathotypes. It has been mapped on chromosome IBS. In the present study, as a first step towards mapbased cloning of Yr15, it was fine-mapped in a F2 population with 825 individuals. According to frequency of retrotransposons in euchromatin regions of the genome and I near the gene cluster, retrotransposon-based molecular markers were mostly used. Three SSR, three IRAP and seven REMAP markers were identified to be linked to the gene with a distance less than 2cM and genetic map near the gene was saturated. Some markers were cosegragated at proximal side of the gene. One of the lRAP and two REMAP markers converted to locus specific and codomiriant SCAR markers. Locus specific and codominat marker, SC792, completely co-segragated with gene. Other two locus specific and codominant markers, SC1600 and SC1028, surrounded the gene in an interval of 1cM. These markers could be used for reliable MAS and map-based cloning of Yr15. Also, it was demonstrated that retrotransposon based markers can be more useful and efficient in fine-mapping of genes controlling agronomically important traits.

Wheat STRIPE (yellow) RUST is an important disease in epidemic years in Iran. In this study, reaction of 64 doubled haploid lines, produced by chromosome elimination method crosses between wheat and maize were evaluated for STRIPE RUST disease. In the seedling stage, these lines were inoculated with race 70E34A+, when the first and second leaves were appeared. Seedling plants were placed in chambers with 50% RH, at 18°C and light period of 12 h in the greenhouse condition. Infection type of seeding was recorded 15 and 17 days after inoculation using scale 0-9. The results showed that, 20 DH lines were resistant, and rest of lines showed moderately resistant to susceptible to STRIPE RUST disease. The resistance was measured by infection type, latent period, and pustule size and pustule density. The analysis of variance showed a significant difference among genotypes.

IntroductionSTRIPE RUST (Puccinia striiformis f. sp. tritici) and leaf RUST (Puccinia triticina Eriks) are among the prevalent and devastating fungal diseases of wheat worldwide. The use of genetic resistance is the most effective, sustainable, and economical strategy for controlling RUSTs. The first step in wheat breeding programs to create the effective genetic resistances (resistant varieties) to RUST disease is to know the characteristics of RUST isolates in different regions, and in the next step, is to identify resistance sources to produce resistant varieties. The objectives of this study were to determine the virulence factors of RUST pathogens to resistance genes in international standard and differential cultivars and lines associated with each RUST and to evaluate the response of promising wheat lines to STRIPE and leaf RUST races to identify resistance sources.Materials and methodsFive STRIPE RUST isolates collected from the regions of Karaj, Sari, Zarqan, Moghan, and Mashhad, and three leaf RUST isolates collected from the regions of Gorgan, Moghan, and Ahvaz were identified. To identify the sources of resistance to the studied STRIPE and leaf RUST races, the reaction of 23 promising wheat lines (ERWYT-N99) was evaluated at seedling stage (RUSTs greenhouses of Seed and Plant Improvement Institute, Karaj, Iran) and adult plant stage (research station of the Ardabil Agricultural and Natural Resources Research and Education Center, Moghan, Iran). The resistance reaction of wheat lines to five STRIPE RUST isolates and three leaf RUST isolates at the seedling stage was evaluated in separate experiments based on randomized complete block design with three replications. The resistance reaction of wheat lines at the adult plant stage was also investigated under field conditions and natural contamination of STRIPE and leaf RUSTs using disease progression parameters on the plant and disease severity percentage appeared on leaves.Research findingsThe results of determining the race of the isolates showed that the STRIPE RUST isolates collected from Karaj, Sari, Zarqan, Moghan, and Mashhad regions included the races of 14E158A+, Yr27; 142E158A+, Yr27; 6E134A+, Yr27;, 166E62A+, Yr27; and 6E142A+, Yr27; respectively, and the leaf RUST isolates collected from Gorgan, Moghan, and Ahvaz included FDTTS,  FKTTS, and FJTTS, respectively. The resistance genes Yr1, Yr4, Yr5, Yr10, Yr15, Yr24, YrSU, YrSP, and YrCV were identified as the effective resistance genes against STRIPE RUST races, and the resistance genes Lr1, Lr2a, Lr9, Lr19, and Lr28 were identified as the effective resistance genes against leaf RUST races. The results showed that there was a significant genetic difference between the reaction of promising wheat lines to STRIPE and leaf RUST races. Based on the results of the reaction of wheat lines to STRIPE RUST races in both seedling and adult plant stages, wheat lines were divided into two main groups (resistant and semi-resistant to semi-susceptible), so that except for lines number 21 and 22 (with semi-resistant to semi-susceptible reaction), other wheat lines showed acceptable resistance to STRIPE RUST races. Based on the reaction of promising wheat lines to leaf RUST races in both seedling and adult plant stages, the lines were also classified into three main groups (resistant, semi-resistant to semi-susceptible, and susceptible), and lines number 1, 3, 11, 14, 21, and 22 showed acceptable resistance to leaf RUST races.CoclusionDeveloping durable and effective resistance is one of the crucial strategy for mitigating the detrimental effects of wheat diseases and reducing the excessive reliance of chemical fungicides. In addition to exhibiting high yield potential and desirable agronomic traits, newly developed wheat lines must harbor an acceptable level of resistance to the most prevalent wheat diseases, particularly RUSTs, to qualify for commercialization. The presence of RUST pathogens poses a significant threat during the growing season. If environmental conditions favor their pathogenicity, the damage inflicted can be substantial, warranting the development of robust resistant varieties. The resistant lines identified in this study can be used as sources of resistance in breeding programs to develop wheat varieties resistant to STRIPE and leaf RUST diseases.

Dialer crosses have been used in genetic research to determine the inheritance of important traits among a set of genotypes and to identify superior parents for hybrid or cultivars development. Genetic control of infection type of STRIPE ruts was studied in a half-diallel design using six wheat cultivars, Tiritea (a susceptible check), Tancred, Kotare, Otane, Karamu and Briscard. These cultivars and their 15FlS. were evaluated by three STRIPE RUST path types 7EI8A-, 38EOA + and 134E134A +. For each pathotype a randomized complete block design with three replications was conducted with 21treatments. The biplot method was arranged by the first two principal component (PCs). Analysis of variance showed significant differences between 21 treatments for infection type. Changing the path types caused reversal of the domillance in most of the crosses. Briscard for the path types 38EOA+and 134E134A+, and Kotare for the pathotype 7E18A- had the highest GCA effects for infection type, so they can be used in breeding programs for development of resistant cultivars to STRIPE RUST. The highest negative SCA was observed in crosses of Kotare x Karamu for 7EI8A-, Tiritea x Otane for 38EOA+ and Briscard x Kotare for 134E134A+. These SCA values indicate the presence of dominance for the lower infection type. The results indicated that infection type, as a component of resistance is under genetic control and seiection for this character would be effective in wheat breeding programs.

To study the inheritance of STRIPE RUST resistance and to estimate the genetic components of resistance in wheat, F1, F2, BC1 and BC2 generations derived from crosses between two resistant cultivars and one susceptible cultivar (Bolani) along with parental lines were evaluated in a randomized complete block design (RCBD) with three replications in greenhouse. The plant materials were inoculated with pathotype 4E0A+ of STRIPE RUST. In all plants, resistance components including latent period and infection type were recorded after appearance of pustules on leaves. Generation mean analysis revealed that additive, dominance and epistasis play major roles in increasing and decreasing of latent period and infection type, respectively. In spite of significant additive effect, dominance effect was more important in controlling these two characteristics. Broad sense heritability and narrow sense heritability estimates for latent period was 0.33 and 0.28 and for infection type was 0.42 and 0.39 respectively.

Introduction: Yellow (STRIPE) RUST, caused by P. striformis f. sp. tritici, is one of the most important foliar diseases of wheat. The disease has been reported in temperate, cool, and higher altitudes regions, where wheat is grown. The widespread of the disease has always threatened wheat production and resulted in 30 to 100% losses in yield. Although chemical method is common throughout the world, it is not practical by farmers in developing countries. The most alternative practical way is to use genetic resistance which is economical and safely to environment. Two types of genetic resistance, including race-specific and non-race-specific resistance, are well known. Race-specific resistance operates based on the gene for gene hypothesis. Following the evolving of new races of pathogens, race-specific resistance becomes almost ineffective within 3–, 5 years. Non-race-specific resistance is controlled by small-effect (additive) genes and is long lasting. The wisely use of genetic resistance through the combination of race-specific and non-race-specific genes is suggested for the effective management of RUSTs. In view of the above, it is important to determine the properties of wheat germplasm for the detection of such diverse resistance. Therefore, the present study was performed to identify genetic sources with different resistance types to enhance the improvement of breeding operations for the release of cultivar in Iran. Materials and Methods: In order to study of seedling reactions, a total of 191 dry land wheat lines were used. Seeds of each genotype (5-7 seeds) were planted in 7× 7 cm pots under controlled conditions in the greenhouses of Karaj. Seedlings were inoculated with two pathotypes of pathogen (6E158A+ and 6E150A+, Yr27). The inoculated Plants were transferred to a growth chamber at 10°, C with 16 h of light and 8 h of darkness for 24 h. Plants were then transferred to greenhouses at 6–, 10°, C temperature. 14-17 days later, seedling infection types were recorded based on a 0-4 scale (Stakman et al., 1962). The same number of studied lines at the seedling stage, were also used to evaluate the adult plant responses. The germplasm was cultivated at Ardebil Agricultural Research Station during the 2015-2016 cropping year. About eight grams seeds of each entry were planted in two-row plots of 1 m length with 30 cm distance. Plots were spaced at 65 cm. Infection types were recorded in the adult plant stage according to the method of Rolfs et al. Disease severity data were used to calculate the area under the disease progress curve (AUDPC). The relative area under the disease progress curve was also compared by comparing each line with the susceptible cultivar (assuming 100% susceptible cultivar value). In order to determine different resistance groups according to the method of Bux et al. (2012), lines with rAUDPC between 0-10 was considered as resistant group, rAUDPC = 11-30 as intermediate and lines with rAUDPC values above 30 were classified as susceptible. Results and Discussion: Seedling evaluation using pathotype 6E158A+ showed that of 63 resistant genotypes, 31 genotypes were from winter wheat, 4 from durum wheat and 28 genotypes of spring bread wheat. The seedling reactions using pathotype 6E150A+, Yr27 indicated that of 64 resistant genotypes, 26 genotypes were of winter bread wheat, 8 genotypes of durum wheat and 30 genotypes of spring bread wheat. The results at seedling stage also revealed that 51 genotypes were resistant to both pathotypes, of which 24 were genotypes of winter bread, 4 genotypes of durum wheat and 23 genotypes of spring bread wheat. Of the 191 genotypes studied, 24 (12. 5%) genotypes also showed resistance at both seedling (against to two pathotypes) and adult plant stages. In field conditions, 81 genotypes were susceptible and 110 (57. 6%) were resistant. Among the resistant genotypes, the differences were observed based on the values of the relative area under the disease progress curve (rAUDPC). The response of winter wheat, spring wheat and durum wheat varied. Among the winter bread wheat, spring and durum wheat genotypes, 9 (12. 5%), 38 (44. 2%) and 4 (12. 1%) genotypes had low levels of the area under the disease progress curve (rAUDPC = 0-10), respectively, and were classified as resistant group. A group of genotypes also had moderate values of the area under the disease progress curve (rAUDPC = 3-11), of which 16 (22. 2%), 37 (43%) and 11 (33. 3%) genotypes were of winter, spring, and durum wheat genotypes, respectively. Conclusion: A number of genotypes having seedling resistance were identified with probability of resistance gene/genes,Yr3v, Yr3a, Yr4a, Yr4, Yr5, Yr10, Yr15, Yr16, YrCV, YrSD, or unknown genes. Most winter wheat genotypes lacked seedling resistance. Some of the genotypes had adult plant and slow RUSTing resistance (Nonrace-specific or durable resistance) and this percentage was higher among spring bread wheat than winter wheat and durum wheat genotypes. This germplasm with various sources of resistance will be useful in integrating both types of resistance through the pyramiding of genes for durable resistance and eventually high-yielding resistant varieties will be introduced to farmers.

yellow or STRIPE RUST caused by Puccinia striiformis f. sp. tritici, is the most important disease in terms of the amount of damages to wheat crop in the worldwide. The best method used to control this disease is the application of resistant cultivars. So, It is absolutely necessary for determine the virulence factors of STRIPE RUST and evaluation of host resistance in different growing level. To study evaluation of resistance sources to STRIPE RUST, twenty wheat genotypes were separately evaluated in the forms of randomized complete block design with three replications in the seedling stage under greenhouse condition with 20 races of STRIPE RUST 6E158A+, 230E158A+, 198E150A+, 134E150A+, 6E150A+, 166E150A+, 198E130A+, 166E158A+, 70E0A+, 6E16A+, 102E134A+, 6E134A+, 6E130A+, 6E150A+, 6E6A+, 70E50A+, 6E18A+, 134E22A+, 166E254A+and166E134A+. The components of resistance including latent period and infection type were recorded under greenhouse condition. Results indicated genotypes were evaluated in terms of both traits were significant at 1% level.30% genotypes (Mv17, M-85-7, Aflak, Morvarid, Sivand and Parsi) were completing resistant to all races studied.Probably, in resistant genotypes each of the resistance genes, Yr1, Yr3, Yr4, Yr5, Yr10, Yr15, Yr24 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. Resistant genotypes have seedling resistance genes, which could be used as resistance source in breeding programs.

Inheritance of resistance to STRIPE RUST was studied in wheat by determining the responses of 5 hexaploid wheat cultivars and 10 F1 progenies of their diallel mating crosses, against 2 races of pathogen including 174E174A+, 134E134 A+ in completely randomized design with 3 repetitions under greenhouse conditions at Tehran University. The components of resistance including latent period, infection type, pustule size and pustule density were recorded after inoculation over time. Analysis of variance showed significant differences among genotypes for all traits. Kotari cultivar had the most GCA among the parents for resistance increase. For the 2 races, there was dominance effect for most allels. In addition for both races the additive component compared to the non-additive component was more estimated to be more important to decrease infection type. Whereas the non-additive component was calculated to have more impact to increase size and density of pustules. The results of variance analysis of Vr+Wr and wr-Vr showed the existence of dominant effect for the 2 races. Combined analysis of variance also indicated significant effects for race and race*genotype interactions for all traits suggesting that there differences in pathogenicity of races as well as the presence of specific genes in some of the cultivars.