Ayub Agricultural Research Institute, Faisalabad
Shakra,Jamil, , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Different biotic and abiotic stresses are hampering wheat yield across different geographic regions. Among biotic stresses, wheat rusts are principal cause of yield reduction. Whereas among abiotic stresses, drought is the principle cause of reduction in growth and lowering yield potential. So developing rust resistance and drought tolerance in wheat germplasm is needed, which requires assessment of genetic potential of current cultivars against these stresses to identify variation among existing germplasm. Screening of genotypes under naturally prevailing races of rust species is the better and inexpensive approach. In the present study 65 genotypes including five checks (AARI-11, Chakwal- 50, Aas- 11, Morocco and Galaxy-13) were evaluated for adult plant response to wheat rusts and water deficit conditions. Experimental material was planted in four blocks each having new entries along with repetition of five checks in augmented design. Data was recorded on morphological traits including plant height, peduncle length, spike length, productive tillers per meter, flag leaf area, number of spikelet per spike, grains per spike, single head weight, 1000 grain weight, days to maturity and grain yield per acre. Significant variation was observed among genotypes for all the studied traits. On the basis of performance G39 and G36 were better than commercial drought check Chakwal-50 in almost all the traits. However rust screening under natural rust infestation revealed that although Morocco showed susceptible (S) response yet only six genotypes were susceptible to yellow rust whereas all others were resistant. In case of leaf rust 29 were completely resistance, 25 were moderately resistant, seven were moderately susceptible and only four were completely susceptible to currently active races of leaf rust. However, in the case of stem rust, 61 genotypes showed complete resistance to stem rust, two showed moderately resistance and two were moderately susceptible. Information obtained from this study would be favorable for breeding rust resistant and drought tolerant cultivars.
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.
Genetic Resources Institute, Azerbaijan
N.,Aminov, A., Jahangirov, H., Hamidov, Aigul, Abugalieva, Vladmir, Shamanin, Alexey, Morgunov, , , , , , , , , , , , , , , , , ,
Hexaploid synthetics have become widely used in bread wheat improvement in recent years, enabling the introduction of specific traits as well as enhancing genetic diversity and development of valuable germplasm. This study demonstrated the difference between two groups of primary synthetics in terms of development rate, plant height, rust reactions, and productivity components. During 2015 and 2016, three groups of synthetics were studied in Azerbaijan (3 sites): Baku (0 masl) under irrigated conditions, Gobustan (850 masl) under dry rainfed conditions and Ujar (20 masl) under irrigated conditions with high salinity. Germplasm was also evaluated for diseases and agronomic traits in Omsk (Russia) in 2016.
All primary synthetics were resistant to leaf rust, several to stem rust, and few to stripe rust. Stripe rust occurred in all years at all sites, proving its importance as major wheat pathogen. Its severity reached intermediate levels in Baku in 2016 (33.7%) and in Gobustan in 2015 (26.8%), and epidemic level in Gobustan in 2016 (72.7%). Gobustan also experienced high levels of stem rust in 2016. These two diseases substantially reduced grain productivity in Gobustan in 2016, especially 1000 kernel weight (30.2 g) and grain weight per spike (1.17 g). . Superior genotypes from all three groups were identified that combine high expression of spike productivity traits and stress tolerance index. Five superior synthetics were selected from each of the three groups, based on grain weight per spike. Only four of these demonstrated resistance to stripe rust (entries 13, 15, 31, and 32). Japanese synthetics (group 3) were susceptible to stripe rust but all demonstrated resistance to stem rust. Synthetics from groups 1 and 3 were all resistant to leaf rust when tested under severe disease pressure in Omsk in 2016.
1,3 Colegio de Postgraduados-Fitosanidad, Campus Montecillo, Texcoco, 56230, Estado de M?xico, M?xico
Julio,Huerta-Espino, Ravi, P. Singh, Caixia, Lan, Sridhar, Bhavani, Reyna I., Rojas-Mart?nez, Ignacio, Benitez-Riquelme, Cristian, Nava-D?az, Mandeep, Singh Randhawa, , , , , , , , , , , , , ,
Leaf rust and stripe rust caused by the fungi Puccinia triticina and P. striiformis f. sp. tritici, respectively, are important diseases of wheat and represent a significant threat in most wheat producing regions worldwide. Growing resistant varieties and the identification and characterization of new sources of resistance are necessary to combat the threat from the evolving pathogen population. Bread wheat (Triticum aestivum L.) line 'Kijil' developed at CIMMYT showed adult plant resistance (APR) to leaf rust (LR) and stripe rust (YR). The genetic basis of the resistance was investigated using 198 recombinant inbred lines (RILs) derived from the cross of susceptible Apav#1 and resistant Kijil. Field phenotyping of parents and RILs were conducted at El Bat?n, Toluca and Ciudad Obreg?n, Mexico during 2016 and 2017. Pearson correlation coeffcients (P< 0.0001) were high for disease severities between two years of evaluations: LR (r= 0.90) and YR (r= 0.83). Correlations (r= 0.30-0.76) were also significant between LR and YR in all environments. Genetic analyses indicated that 3 to 5 genes of additive effects governed resistance to both rusts. RILs carrying the pleiotropic APR gene Lr46/Yr29/Sr58 showed 23 and 41% of disease severity for LR and YR respectively, whereas lines lacking it had 55 and 78% severities. RILs positive for Sr2/Yr30 showed 66% YR severity, whereas those negative displayed 78%. In addition, lines carrying the race-specific gene Yr17/Sr38 showed 28% YR severity in contrast to non-carriers that displayed 78% severity. We conclude that Kijil possesses a complex nature of resistance.
ICAR-IIWBR, Regional Station, Flowerdale,Shimla 171002 H.P. India
Pramod,Prasad, OmPrakash, Gangwar, Hanif, Khan, Siddanna, Savadi, Subodh, Kumar, , , , , , , , , , , , , , , , , , , ,
Stem rust (Puccinia graminis tritici) (Pgt) epidemics have been reported from many wheat growing areas of the world. Stem rust races with virulence to Sr31 (Ug99 type races),are a threat to wheat producing African countries. Currently 11 different variants of the Ug99 lineage have been reported from different countries. Despite no report of Ug99 variants from any of the South Asian countries, the efforts are in place to counter the possible introduction of virulent wheat stem rust races. Stem rust surveillance has been a major component of the rust resistance breeding worldwide. This study reports virulence phenotypes and functional SSR marker based genotypes among stem rust collections in the Indian subcontinent during 2009 to 2015.
Wheat stem rust samples were analyzed on differential sets used for pathotype identification in India. Twelve pathotypes of Pgt were identified in a total of 574 samples analyzed. Pgt pathotypes 40A and 11 were identified in 36% and 32% of the samples, respectively. The stem rust resistance genes Sr7a, Sr26, Sr27, Sr31, Sr32, Sr33, Sr39, Sr40, Sr43, SrTmp and SrTt3 were found to confer resistance to the field population identified during this period. The analysis of SSR marker genotypes data revealed a high degree of variability in the Pgt population, with mean gene diversity and polymorphic information content (PIC) values of 0.56 and 0.50, respectively. STRUCTURE software divided the Pgt populations in to four subpopulations with some admixtures. The FST values of pairs of subpopulations ranged from 0.35 to 0.93 which indicated that the four sub-populations were significantly differentiated. The analysis of molecular variance (AMOVA) determined that 16%, 69% and 15% of the totl variation was between population, among and within individuals, respectively. The information generated here could be a useful guide for resistance breeding and gene deployment programmes for saving South Asian wheat from stem rust.
State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University
Yuan,Tian, Yan, Meng, Hengbo, Ma, Lili, Huang, Zhensheng, Kang, , , , , , , , , , , , , , , , , , , ,
Stripe rust, caused by Puccinia striiformis Westend f.sp. tritici, is currently one of the most prevalent and damaging disease on wheat. Up to now, some genes in wheat which are resistant to wheat stripe rust have been cloned, but little is known about the corresponding avirulence gene according to the gene-for-gene hypothesis. A population containing 118 progeny isolates population acquired by selfing an isolate, PL17-7, with virulence to Yr26 was derived. Seventy-two progeny isolates were different in genotype depending on 92 simple sequence repeat (SSR) markers. The progeny population segregated for avirulence to Yr6 at one locus (3 avirulent :1 virulent ratio). The parental isolate and 72 of 118 progeny isolates were resequenced to find candidate avirulence genes corresponding to Yr6. Overall, 7.6 million reads per sample were obtained and mapped to the draft genome of a Chinese Pst isolate CY32. The median depth of coverage was 63.6 fold. For each isolate, between 97.6% and 98.1% of the sequence reads were mapped to the race CY32 genome, which covered between 87.3% and 95.4% of the reference genome bases. An average of 97357 single nucleotide polymorphisms (SNP) per isolate was found, which covered 8.1% of the reference genome. Different SNPs and Indels were found when isolates virulent and avirulent to wheat cultivar containing Yr6 were grouped into two groups. Though screening discrepant SNP and indel in these two groups, candidate avirulence genes corresponding to Yr6 may be found.
International Center for Agriculture Research in Dry Areas (ICARDA)
ahmad,amri, El-Haddoury, Jamal, , , , , , , , , , , , , , , , , , , , , , , , , ,
Constant climatic change and rapid evolution of diseases and pests have created challenges for plant breeders to find novel sources of resistance within cultivated gene pool. However wild (alien) relatives of crops still carries many promising resistance genes to biotic and abiotic stresses. Plant breeders around the world have successfully attempted to recover some of the beneficial genetic diversity lost (or never included) during the domestication and crop improvement process by crossing cultivated varieties with wild species to introgressed many valuable genes into crops like wheat and barley. This pre-breeding attempt to regain the genetic diversity of crops based on crop wild relatives (CWR) had been started at ICARDA 1994. Furthermore, The Global Crop Diversity Trust (GCDT) recently provided a grant to ICARDA within the Crop Wild Relatives (CWR) project to strengthen the research on use of genetic resources in pre-breeding of barley and grass pea. The pre-breeding activity in barley is focused on transferring genes of resistance to complex diseases and pests (scald, spot blotch and barley gall midge), improving tolerance to drought, heat and salinity, and enhancing the nutritional value through improving Iron and Zinc concentrations and amylases activity. Crosses were made between wild barely H. Vulgare X cultivated barley H. Vulgare subsp. H. spontaneum. The main objective of pre-breeding in Grasspea is transferring genes of low or no ?-ODAP from crossable species L. cicera and L. amphicarpus, L. tingitanus, L. aphaca, L. odoratus, L. sphaericus, L. nissolia, and L. aureus. Interspecific crosses were made between L. sativus x L.cicera followed by embryo rescue. Currently all the pre-breeding lines with targeted traits are under screening against the respective selection pressures using precision phenotyping..
Omsk State Agricultural University, Omsk, Russia
Elena,Salina, Yuriy, Zelenskiy, Alma, Kokhmetova, Mehran, Patpour, Mogens, Hovm?ller, Pablo, Olivera, Les, Szabo, Yue, Jin, Marcel, Meyer, Chris, Gilligan, Matthew, Hort, Dave, Hodson, Alexey, Morgunov, , , ,
Short season, high latitude spring wheat is grown on 7 million ha in Western Siberia and 10 million ha in Northern Kazakhstan. Despite relatively low wheat yields (1.5 t/ha), the region is extremely important for regional and global food security. Leaf rust dominates, occurring three years out of five, especially in favorable years with higher rainfall. Since 2010, stem rust has been observed at an increasing number of sites. The first large-scale stem rust outbreak occurred in 2015 and affected about 0.5-1 million ha in Omsk, Western Siberia. In 2016, 2 million ha were affected in the Omsk and Altay regions, while 1 million ha in the Kostanay and Northern Kazakhstan regions were affected in 2017. Estimated yield losses reached 25-35% each year. Factors associated with the outbreaks included: higher rainfall in late June and July; cultivation of susceptible varieties; and an increased area planted to winter wheat, which serves as a source of inoculum. Sampling and race analysis revealed a diverse pathogen population, indicative of a sexual recombination. A total of 51 races were identified from 31 samples taken in 2015 and 2016. All races were avirulent on Sr31. The majority of varieties released and cultivated in the region are susceptible to stem rust and require replacing. A recent study of 150 local resistant varieties and breeding lines indicated that the genetic basis of resistance was limited to Sr25, Sr31, Sr36, Sr6Ai, Sr6Ai#2, and additional unknown major genes. Adult-plant resistance to stem rust was observed in less than 20% of the germplasm. The potential impact of these large stem rust outbreaks on other wheat growing regions is being investigated by analyzing spore wind dispersal patterns. Further research is required to understand and mitigate the sudden appearance of stem rust as a disease of economic importance.
Study at Omsk State Agrarian University was supported by the Russian Science Foundation (project No. 16-16-10005).
USDA-ARS Cereal Disease Laboratory
Maria,Ordonez, Silvia, German, Kun, Xiao, Amy, Fox, Maricelis, Acevedo, , , , , , , , , , , , , , , , , , , ,
The leaf rust pathogen, Puccinia triticina is widespread across all major wheat growing regions worldwide. Collections of P. triticina were obtained from common and durum wheat in North America, South America, Europe, South Africa, the Middle East, East Africa, Russia, Central Asia, China, Pakistan and New Zealand in order to determine the genetic diversity within each region and genetic relationship between regions. A total of 831 single uredinial isolates were characterized for virulence to isogenic lines of Thatcher wheat and for molecular genotype at 23 SSR loci. The isolates in East Africa and Europe were the most diverse for the average number of effective alleles per locus, while the populations in Russia and North America were the least diverse. The isolates in Europe and South America had the highest number of multilocus genotypes of 81 and 75, respectively, and were the most diverse for Shannon's genotypic diversity. All populations had significantly higher levels of Ho compared to He at individual SSR loci, and had highly significant values of Ia and rd which indicated clonal reproduction. Europe had the highest number of distinct SSR genotype groups with eight, and Russia had only two SSR groups. The populations in North America and South America; Russia and Central Asia; the Middle East and East Africa; were closely related for SSR genotype based on Nei's genetic distance. Based on k means clustering and DAPC of SSR genotypes, isolates virulent to durum wheat were placed into a single separate group, and isolates virulent to common wheat were placed into five other groups. Twenty-seven SSR genotypes were found in different continental regions. Isolates with identical or highly related SSR genotypes also had identical or similar virulence, which indicated historical and current migration of P. triticina worldwide.
Wheat Research Institute, Ayub Agricultural Rsearch Institute Faisalabad
Amna,Kanwal, Mehwish, Makhdoom, Javed, Ahmed, Makhdoom, Hussain, , , , , , , , , , , , , , , , , , , , , ,
Wheat is the most important cereal crop in Pakistan because it contributes major portions of daily calorie intake. Rust is an increasing threat to wheat production and ultimately food security in Asian countries. The purpose of the present study is to identify the suitable wheat lines that could significantly resist rust pathogen without compromising yield. 60 durum wheat lines, entered in preliminary and regular yield trials, were tested for various morphological and physiological traits along with adult plant disease reaction under natural rust infestation. Results indicated that there was higher incidence of yellow rust as compared to leaf rust as ten genotypes were susceptible to leaf rust. Whereas seven lines were moderately susceptible, 14 were moderately resistant and two were completely susceptible to yellow rust. These findings suggested that future breeding program should be directed towards the developments of resistant cultivars that could resist variable strains of rust pathogen under changing climatic conditions.