Within the framework of study on rust fungi (Uredinales) of Khuzestan, 23 rust species belonging to different genera were identified. Of these, 20 species viz., Aecidium rubellum, Melampsora cf. pulcherrima, Phakopsora zizyphi-vulgaris, Phragmidium bulbosum, Ph. rosae-lacerantis, Puccinia aeluropodis, Pu. calcitrapae, Pu. cancellata, Pu. conclusa, Pu. malvacearum, Pu. pulvinata, Pu. rhagadioli, Pu. scirpi, Tranzschelia discolor, Uromyces anthyllidis, U. glycyrrhizae, U. gypsophilae, U. lineolatus, U. loti and U. rumicis are reported as new members for Khuzestan rust flora. Moreover, several new host species are reported for some identified rusts in Iran. Examination of the type and authentic specimens of Puccinia rhagadioli and Pu. garhadioli revealed that both species are identical and, therefore, Pu. garhadioli is considered as a taxonomic synonym of Pu. rhagadioli.

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.

Two rust fungi from Iran are described as new species, viz. Puccinia - hedjaroudei on Scutellaria multicaulis (Lamiaceae) and Phragmidium gorganense on Rubus caesius (Rosaceae). A key to the species of Phragmidium on Rubus spp. In Iran is also provided. All holotypes are preserved in the fungus reference collection of the Ministry of Jihad-e Agriculture (IRAN), located in Department of Botany of Iranian Research Institute for Plant Protection, Tehran, Iran. Isotypes are at NCRI.

Central Alborz region has been explored since 18th century by different botanists and mycologists. The results of all these expeditions are several publications about flora and mycobiota of the region. Literature review of publications about Central Alborz showed no special publication about rust mycobiota of this region. The lack of information about rust mycobiota of Central Alborz was the main reason for doing this research. During our study, several rusted specimens were collected and identified, thirteen of which belonged to genera Phragmidium, Puccinia and Uromyces reported here. Among the studied taxa, Phragmidium asiae-mediae, Ph. tranzschelianum on Geum kokanicum and Rosa iberica, respectively; Puccinia hieracii var. piloselloidarum on Hieracium woronowianum, Uromyces geranii on Geranium spp. and Ur. eurotiae on Krascheninnikovia ceratoides are newly reported from Iran. Uredinial state of Ph. asiae-mediae and Ur. bupleuri are reported here for the first time. Puccinia monopora is reported on Asperula glomerata for the second time since 1901. New rust taxa for Central Alborz and new hosts for Iranian rust mycobiota are also reported.

In the present study, two species of rosaceous rust fungi are reported from Iran. Ochropsora ariae is newly reported for Iranian rust mycobiota. This is the first report of a member of the genus Ochropsora from Iran. Kuehneola uredinis is reported for the second time from Iran since its first report in 1958 under the name K. albida. Pyrus boissieriana is reported as a new host (matrix nova) for O. ariae. Rubus hirtus is also a new host for K. uredinis in Iran. Both identified rust species are documented by descriptions and LM photomicrographs.

Four rust raxa in 3 genera and one form genus are newly recorded for Iran. Among these, Melampsoridium is a new genus for the Iranian rust flora. M. carpini on Carpinus sp., Coleosporium inulae on lnula salicina ssp. aspera, Puccinia saniculae on Sanicula europea and Uredo Otostegiae on otostegia persica are repoted for the first time in Iran. Number of urediniospore pores formerly believed 2 in U. otostegiae revealed to be 2-5.

Eight cyperaceous Puccinia and Uromyces, viz.Puccinia cariciola, P. conclusa, P. cyperi, P. eriophori, P. scbpi and Uromyces lineolatus subsp. lineolatus are reported as new to Iran. The uredinial stage of P. dioicae is reported as a new stage for this rust in Iran. Hosts new to P. eriophori are also given. Included is a key to the cyperaceous rust species in Iran.    

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.

A study was conducted to identify SSR markers linked to leaf rust resistance genesLr24 andLr28 and to be used for Marker-Assisted Selection (MAS) to transfer both genes to a widely cultivated wheat variety MP 3299 under rainfed condition. F2 individuals of the cross MP 3299×NIL PBW 343 were used for generating genotypic data employing closely linked SCAR markers S73719 and S421570 toLr24 and Lr 28, respectively, and further subjected to bulk segregant analysis. A total of 70 SSR markers that amplify sequences on long arm of chromosome 3D and long arm of chromosome 4A were used for polymorphism assay between the parents MP 3299 and NIL PBW 343. Eighteen SSRs were polymorphic between the parents, of which 10 were located on chromosome 3DL and eight on chromosome 4AL. Three SSR markers out of 18 polymorphic markers differentiated two contrasting bulks and further used for F2 genotyping. Finally, one SSR marker i.e. ‘barc 71’ linked to SCAR marker SCS73719 at a distance of 3.36 cM based on the per cent recombination frequency was identified. Thus, the newly identified SSR marker barc 71 linked toLr24 can serve as a useful marker in gene pyramiding instead of SCAR marker SCS73719.