Agriculture & Agri-Food Canada
Wheat cultivar McNair 701 carries resistance gene SrMcN and is used as a differential line to identify Pgt races using the international letter code nomenclature. The inheritance and location of the resistance gene has not been characterized. We developed a doubled haploid (DH) population from cross LMPG/McNair 701 to study the genetics and chromosomal location of SrMcN. A DH population inoculated with race QCCJB segregated 100 resistant : 94 susceptible, a 1:1 ratio (?2=0.186, P=0.666, NS) indicative of segregation at a single locus. This gene was mapped to chromosome 2DL using the Infinium 90k platform. The map position of SrMcN was similar to that of Sr54, one of two genes previously found in Norin 40. Comparison of stem rust seedling reactions using 12 diverse Pgt races indicated that McNair 701 and an Sr54 line derived from Norin 40 had an identical pattern of responses and similar low infection types (IT=12-) to races LCBNB and QCCJB. Based on the chromosomal location on 2DL and identical seedling responses to Sr54, it is likely that the resistance gene in McNair 701 formerly known as SrMcN is Sr54. This finding will be confirmed by a test of allelism.
Institute of Molecular Biology and Biotechnology, Azerbaijan National Academy of Sciences
Shahriyar Sadigov, Alamdar Mammadov, Irada Huseynova
Rust of cereals are considered to be an important disease in many countries, including Azerbaijan. One of these is stem rust caused by Puccinia graminis f. sp. tritici (Pgt). Extensive research on the identification of wheat stem rust resistance genes and effectiveness of these genes in various geographical regions have been conducted. Genetic resistance is one of the most effective ways for controlling stem rust. Sixty-nine stem rust resistance genes (including 45 identified Sr genes and 24 genes with temporary designations) are registered in the Komugi Wheat Genetics Resource Database. It is important to use proper combinations of resistance genes in developing lasting resistance wheat. The main purpose of the study was to identify lines caring Sr11, Sr26 and Sr31 genes, which are effective to the predominant Pgt races in Azerbaijan. Durum and bread wheat genotypes differing in their disease resistance, productivity and other physiological traits were chosen from the wheat gene bank of the Research Institute of Crop Husbandry (Baku, Azerbaijan) for analysis. DNA extraction was carried out according to standard CTAB protocol. RT-PCR performed using KASP markers (KASP_6BL_BS0074288_51 and KASp_6BL_Tdurum contig55744_822) identified nine durum genotypes (out of 34 genotypes) and seven wheat genotypes (out of ten genotypes), caring Sr11. Using the dominant STS marker (Sr26#43) a diagnostic 207 bp amplicon for Sr26 gene, was observed in 11 of the 42 wheat genotypes tested. In eight of the 42 wheat genotypes tested, the diagnostic 1,110 bp amplicon was observed using the Lr26-Sr31-Yr9 locus specific marker iag95, characteristic of Sr31 gene located at 1BL.1RS translocation. For the first time, wheat germplasm in Azerbaijan was analyzed using KASP genotyping technology and genetic resources, and resulted in the identification of wheat lines with effective resistant to Puccinia graminis f. sp. tritici race TKTTF.
The University of Sydney
Davinder Singh, Peter Dracatos
Following the introduction of wheat stripe rust into Australia in 1979, an uncharacterized resistance (YrA) was identified in both Australian and International spring wheats. Genetic analyses of YrA indicated it was a pair of complementary genes, which were mapped to chromosomes 3DL and 5BL and designated Yr73 and Yr74, respectively. While selection Avocet 'R' carries both genes, selection Avocet 'S' carries Yr73 only. P. triticina pathotype (pt.) 104-1,2,3,(6),(7),11 +Lr37 ("104-VPM"), first detected in Australia in 2002, most likely arose via mutation from pt. 104-1,2,3,(6),(7),11 ("104"), with added virulence for Lr37. Interestingly, while both pathotypes are avirulent on Lr13, 104-VPM shows a much lower Infection Type (IT, ";1") than pt. 104 ("X++3") on several genotypes carrying Lr13 (e.g.Avocet 'R', Avocet 'S'). Other Lr13 genotypes (e.g. cv. Hereward) respond similarly to both pts ("X++3"). Genetic analyses of 4 doubled haploid (DH) populations based on intercrosses between Avocet 'R' and genotypes lacking Lr13 segregated in a 1:7 ratio to pt. 104-VPM (";1" : all other ITs). Two populations fixed for Lr13 (viz. Hereward/ Avocet 'R' and Estica/Avocet 'R') segregated 1:3 to pt. 104-VPM (";1" : all other ITs). This segregation pattern fitted a model where two complementary genes interact with Lr13 to generate the low (IT ";1") IT. Mapping of a Teal/Avocet 'R' DH population using 92 lines and 9,035 DArT-Seq markers identified three QTLs: chromosome 2BS (Lr13); chromosome 3DL (co-located with Yr73); chromosome 1DS. These results suggest that Yr73 acts in a complementary manner with a gene on chromosome 1DS to confer leaf rust resistance (IT "X"), and that these complementary genes are additive with Lr13. It appears that Yr73 is a modifier of two independent genes in wheat, one conferring resistance to stripe rust (Yr74 on chromosome 5BL), and one conferring resistance to leaf rust (LrAv on chromosome 1DS).
Aleppo University, Aleppo , Syria
Bassam,Souliman, Naem, Al-Housien, Mohammad Shafick, Hakiem, Miloudi.M, Nachit, , , , , , , , , , , , , , , , , , , , , ,
Wheat yellow rust, caused by Puccinia triticina f. sp. tritici, is the major problem in wheat production in most parts of West Asia. Monitoring of the pathogen virulence factors and their changes provides basic information for the development of an early warning system. Wheat yellow rust has become increasingly important in the Syrian central and coastal areas during the last three years, The objective of this study was to identify races of the pathogen. Yellow rust samples collected at sites in the central and the coastal plains, were analyzed on differential host genotypes with known seedling resistance genes. According to the results of race determination, races 230E150, 166E150, 230E142 and 462E128 were identified. The race 462E128 designated the Warrior race, was identified at several sites across the Syrian central plains at the end of the 2017 growing season (early and Mid-May) when yellow rust exploded suddenly on a number of varieties, despite their previous high resistance ratings. The infections rapidly reached significant levels, in spite of the high temperature (up to 33?C) and the absence of rainfall or irrigation. This new virulent race (462E128) has been able to attack wheat lines with several major resistance gene(s) including: Spaldings Prolific (SP), Yr 3+4, Triticum spelta (Yr5), which remained effective until 2016 in Syria, Virulence to lthe resistance genes Yr1, Yr2, Yr2+, Yr3V, Yr3ND, Yr4+, Yr6, Yr6+, Yr7, Yr7+, Yr9, Yr9+, Yr11, Yr12, Yr18, Yr24, Yr26 Spaldings Prolific (YrSP), Anza (YrA+) Spaldings Prolific (SP), Yr 3+4, Triticum spelta (Yr5) and Selkirk (YrSK) was also found. Virulence to Carstens V (CV), Yr 15/6* Avocet S and Yr 5/6* Avocet S; was not found. According to our findings, the Warrior race has increased in frequency within the mix of yellow rust races in these areas in Syria . It is expected that the Warrior yellow rust race will cause damage on resistant wheat cultivars in 2018.
Ravi P Singh, Julio Huerta-Espino
Aphids are major pests of wheat, able to cause up to 40% yield reduction solely due to direct feeding and up to 60% when feeding is combined with the transmission of viral diseases. Wheat resistance to aphids has proven to be effective in protecting yields and also in reducing the transmission rate of viral diseases. Moreover, aphid resistance is fundamental to reduce the negative impacts that the indiscriminate use of insecticides have on the environment and human health. In this study we report the results derived from the evaluation of 326 synthetic hexaploid wheat (SHW) derived lines against the greenbug (Schizaphis graminum [Rondai]). Primary SHWs were crossed with CIMMYT elite lines and further selected in the breeding pipeline. Therefore, such lines have acceptable agronomic characteristics for its further use in breeding programs. The 326 SHW derived lines were evaluated at seedling stage, in five augmented incomplete blocks, arranged in split-plots, with two treatments (infested vs. non-infested) and with resistant and susceptible checks replicated 16 times. The measured variables were chlorophyll content with a SPAD meter and a visual damage score in a scale 0-100 was also taken. Measurements were recorded when the susceptible check was dead due to aphid feeding. The evaluations were repeated two times for confirmation. Our results indicate the presence of genetic variation for S. graminum resistance. We identified about 4 % of the lines to carry high levels of resistance against this aphid. These lines are currently used in CIMMYT's bread wheat breeding program to incorporate the resistance in elite germplasm.
Institute of Plant Biology and Biotechnology
Makpal Atishova, Aygul Madenova, Kanat Galymbek, Jenis Keyshilov, Hafiz Muminjanov, Alexey Morgounov
Wheat rust diseases are a major cause of yield losses of this crop. Yellow (Puccinia striiformis f. sp. tritici) rust is of the most widespread and dangerous disease of wheat and is the major factor that adversely affects wheat yield and quality. The use of genetic host resistance is the most effective, economical and environmentally safe method of controlling stripe rust that allows elimination of fungicides and minimize crop losses from this disease. Due to the threat of the development of epiphytoties of rust disease it is necessary to identify new donors of resistance to yellow rust and to develop resistant wheat breeding material. In the present study, attention was drawn to the effective yellow rust resistance genes Yr5, Yr10 and Yr15, which were identified in the process of molecular screening of wheat germplasm. Genetic analysis using S23M41 molecular marker linked to Yr5 revealed the presence of this gene in 17 out of 136 promising lines. Thirteen genotypes screened with Xbarc8 generated the DNA fragment associated with Yr15. Three advanced lines with Yr10 were identified using the SCAR marker. Three lines carrying two Yr genes (Yr5 and Yr15) were detected. Combination of Yr5 and Yr10 were found in 15 wheat lines. We identified a number of wheat genotypes highly resistant to stripe rust, which could be further evaluated to release new resistant varieties or to be used in the breeding program.
Egerton University Njoro, Kenya
Ruth Wanyera, James Owuoche, Julian Rodriguez, Annemarie Justesen, Lesley Lesley, Sridhar Bhavani, Cristobal Uauy, Mogens Hovmøller
Emergence of new virulent races of Puccinia striiformis f. sp. tritici (Pst) to stripe (yellow) rust resistance genes in wheat (Triticum aestivum L.) has historically resulted in severe yield losses worldwide. We conducted a study to characterize the virulence profiles of Pst races prevalent in Kenya from historic (1970-1992) and recent collections (2009-2014). Pst isolates collected during surveys in Kenya were characterized at the Global Rust Research Centre (GRRC), Denmark. Yellow rust differential sets (wheat lines with known Yr resistance genes), and strain-specific sequence-characterized-amplified-region (SCAR) markers were used to group the Pst isolates as Pst1 or Pst2. Virulence to Yr1, Yr2, Yr3,Yr6, Yr7, Yr8, Yr9, Yr17, Yr25, Yr27, and the seedling resistance in AvocetS were detected. A total of 12 virulence profiles /races were detected in isolates obtained during 1970 to 1992, while six races were detected from samples collected between 2009 to 2014. In both periods, races with virulence profiles Yr2, Yr6, Yr7, Yr8, Yr25, Yr27, Avs and Yr2, Yr6, Yr7, Yr8, Yr17, Yr25, AvS were common. The SCAR results revealed that both Pst1 and Pst2 strains were present in the Pst isolates tested, Pst1 even in isolates from the 1970s. Additional isolates were also identified with neither Pst1 nor Pst2 profiles. From our findings, race analysis is key to understand the race diversity and pre-breeding efforts for effective resistance gene deployment.
Mohammad Kassem, Ghinwa Lababedi, Naim Al-Husien
Leaf rust is the most common rust in wheat production areas of Syria and causes significant annual yield losses. Using genotypes with durable resistance is the most economical way of controlling the disease. One of the best-known leaf rust resistance genes is Lr46 that confers a slow rusting type of adult plant resistance. The main objective of this study was to identify Lr46 in durum wheat genotypes using morphological and molecular markers. Thirty-two durum wheat genotypes were evaluated for response to leaf rust at the seedling and adult plant stages. Twelve genotypes (37.5%) were resistant (R), 10 (31.25%) were moderately resistant (MR), seven (21.87%) were moderately susceptible (MS), and three (9.37%) were susceptible (S). Molecular marker analyses using SSR marker wmc44 showed that 16 genotypes (50%) carried Lr46/Yr29. The genotypes possessing the marker linked to Lr46/Yr29 could be used for selection of Lr46/Yr29 in breeding for slow rusting resistance in durum.
James Winans, Julian Garcia, Kellie Damann, Gary Bergstrom
In addition to causing Fusarium head blight of wheat and other cereals, Fusarium graminearum is associated with dozens of wild or weedy grass species. Their role in the disease cycle and evolution of the pathogen has not been established despite their widespread distribution. A three-year survey of wild grasses in New York (USA) found that inflorescences and overwintered stems were frequently colonized by F. graminearum. Through a series of controlled laboratory experiments, wheat and five common grass species were compared for their potential to support inoculum production. Artificially infested stem tissue from several grasses both retained F. graminearum at higher rates through a single winter and supported greater ascospore production per dry gram than wheat. Susceptibility of these species to root and crown rot was measured with a modified seed germination assay and a diverse panel of F. graminearum isolates. Differences were seen between host species, and some grasses were resistant to infection. Our results indicate that wild grass species may support significant F. graminearum inoculum production while differing in their suitability for root and crown colonization. Studying interactions between F. graminearum and alternative host plants can improve our understanding of evolution in a broad host range pathogen and our ability to predict the risk of crop epidemics. We are currently evaluating isolates collected from wild grasses for mycotoxin production and aggressiveness on wheat.
Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-University of Bonn
Mohammad Wali,Salari, Kobra, Yusefi, Mohammad, Yusefi, Gul Mohammad, Ajir, Wakil Ahmad, Sarhadi, Jens, L?on, , , , , , , , , , , , , , , , , ,
Bread wheat is a staple food in Afghanistan. Breeding for improving yield and its components in Afghan bread wheat without using new molecular methods such as marker-assisted selection (MAS) and quantitative trait loci (QTL) mapping approaches is difficult. Therefore study of genetic analysis by focus on yield and its components as first steps is necessary. Genetic analyses were performed on a winter wheat core collection of 20 accessions and commercial varieties sampled from different regions of Afghanistan and twenty agronomic traits were evaluated over three years under fully irrigated, rain-fed and drought treatments. Grain yield was the most important trait to water deficit and was highly correlated with other agronomic traits. The germplasm was structured into two sub-populations. Field plots of the genotypes were treated to one of three treatments including full irrigation, rain supplied and rain-sheltered. A randomized complete block design with three replicate was used every year of the trial. For every agronomic trait, variance components, heritability (h2) and genetic correlations was calculated. Results of the study showed that these genotypes may be good source for national breeding programs. The multiple statistical in this study showed that results of genetics correlation and regression analysis are same. Further analysis of these traits with additional experimental data to attain persuasive conclusion is suggested.