International Center for Agricultrural Research in Dry Areas
Wuletaw,Tadesse, Najib, Bendaou, , , , , , , , , , , , , , , , , , , , , , , , , ,
Hybrid wheat is a promising technology to increase yields worldwide. High seed production costs and low heterosis are the main constraints for the development of hybrid wheats. Maximizing heterosis, and selection and utilization of appropriate morphological, floral and flowering traits to optimize outcrossing are important for hybrid seed production. For an efficient hybrid wheat seed production, high anther extrusion is required to promote cross fertilization and to ensure a high level of pollen availability. A pool of 200 elite spring bread wheat male parental lines was visually assessed for anther extrusion in the plastic-house and field environments. Genome-wide association studies (GWAS) for anther extrusion was carried out using a total of 12725 SNP markers. A wide genotypic variance was observed. Several significant (|log10(P)| > 3.0) marker trait associations (MTAs) were detected. Both genotypes and environment influenced the magnitude of the anther of extrusion. The consistently significant markers could be helpful to introduce anther extrusion trait in high yielding varieties and consequently improve hybrid-seed production in wheat.
Kenya Agricultural and Livestock Research Organization
Hanningtone,Wanga, Phelister, Kinyanjui, Sridhar, Bhavani, Thomas, Fetch, , , , , , , , , , , , , , , , , , , , , ,
In 2016 rust surveys were carried out in all the four key wheat growing regions: South Rift (June, July), Mount Kenya (July), North Rift (September) and Central Rift (part of August and September). A total of 304 farms were sampled. Stem rust was detected in 235 (78.3%), yellow rust in twenty-eight (9.3%) and leaf rust in fourteen (4.7%) of the farms. Stem and yellow rust were detected in all the wheat growing regions while leaf rust was detected in South, North and Central Rift. Stem rust infection ranged from TR to 90S with maximum infection in Central Rift (88.3%), Mt. Kenya region (80.3%); South Rift (76.5%) and North Rift (72.4%). Yellow rust infection ranged TR to 60S with maximum infection in Central Rift (16.7%); North Rift(13.3 %) and minimum infection in South Rift( 4.9%),) and Mt. Kenya region ( 1.7%). Leaf rust infection ranged from trace to 50S with maximum infection in North Rift (10.2%) minimum infection in Central Rift (3.3 %) and South Rift (1.2%). Fifty percent of the eight previously released wheat varieties are now susceptible to the Ug99 race. Race analysis results from AAFC Canada suggested the presence of TTKSK which was dominating in North Rift and TTKSK, TTKST and TTTTF were dominant in the screening nursery at Njoro. Yellow rust in the region has increased in the current year owing to the incursion of a probable new race AF2012 which has resulted in increased disease severity on varieties and materials tested in the International nurseries at KALRO, Njoro.
Research Institute of Crop Husbandry, Azerbaijan
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A study was conducted between 2014 and 2016 aiming at determining resistance genotypes of 51 local wheat cultivars in Azerbaijan. The cultivars were evaluated in five different agro-ecological zone including Absheron and Tar-Tar (Irrigated area), Qobustan (dry semi subtropical area),Sheki (rain fed area), and Jalilabad (dry area) against three of the rust pathogens under natural conditions with four repetitions at each region. Field responses under natural infection were recorded according to Modified Cobb's scale for major field responses (Restance (R), Moderelt Resistance MR), Moderet Sesusptable (MS), and Sussciptabe (S) and diseases severity (0-100%). For molecular analysis, genomic DNA was extracted from leaves and the following six markers (Yr5, Yr9, Yr10, Yr15, Yr17, Yr18, and Yr26) were used to identify resistance genes at Plant Genomics College of Agronomy Northwest A&F University China. Marker analysis revealed that Yr5 was present at least in 12 cultivars including Murov, Murov-2, Shafag, Shafaq-2, Nurlu-99,Fatima, Azamatli-95,Agali, Gunashli, Saba Giymatli 2/17, P?rzivan-1, Tale-38. In addition, Yr9 was present in seven culitivars (Pirshahin-1, Layagatli-80, Shafag-2, Zirva-85,Fatima, Agali, Gunashli). Yr10 was present in eight cultivars (Yegana, Garagilchig-2, Yagut, Pirshahin, Shirvan-5, Barakatli-95, Bayaz, Girmizi bugda). And Yr18 was present in Mirbashir-128, Azamatli-95, Gunashli, Akinchi-84, Shirvan-3 cultivars. Yr26 worked well but was not found in any of cultivars. Yr17,Yr15 did not work very well with this method.
Michel E. Ghanem, Sarrah Ben M'Barek, Gustavo Azzimonti, Silvia Pereyra, Silvia Germán, Felix Marza, Amor Yahyaoui, Pawan Singh, Michael Baum, Hans-Joachim Braun
Based on a global network of wheat partners, precision field-based wheat phenotyping platforms are being developed with the support of the CGIAR Research Program on Wheat and co-investing national agricultural research institutes. This collaboration strategy aims to i) strengthen the quality of phenotypic data to fully exploit the potential of genomic data, ii) strategic prioritization of activities based on trait screening capacities and regional needs, iii) sharing knowledge and germplasm to accelerate superior germplasm development and dissemination, iv) development of capacities. Phenotyping activities are being conducted for wheat blast (Magnaporthe oryzae) in Bolivia, Septoria tritici blotch (STB) in durum wheat in Tunisia, and for multiple diseases (leaf rust, Fusarium head blight, and STB) in bread wheats in Uruguay. Subject to further funding, additional platforms will be implemented, to contribute to a faster development of broad genetic based resistant, high yielding wheat varieties, and complementing evaluations currently performed for diseases and heat, drought and yield potential (Kenya, Ethiopia, Turkey, Mexico).
Anvar,Jalilov, Zubaida, Kavrakova, Menu, Mamadyusufova, Botirov, Muhiddin, , , , , , , , , , , , , , , , , , , , , ,
The wild relatives of wheat, the genus Aegilops is of great interest for breeding. Many species of the genus Aegilops are distinguished by such valuable properties as resistance to rust diseases, drought resistance, and salt tolerance.
The evaluation of local wheat varieties on resistance to yellow rust showed that local varieties showed high resistance to the pathogen and were amazed from 0 to 10 %. Evaluation of Aegilops species for resistance to yellow and brown rust, showed that the species Aegilops triunciales showed high resistance to yellow and brown rust, except Ae. triunciales, collected in the Rudaki district and showed moderate resistance to brown rust - 20%. The view of the Aegilops cylindrical collected in the Rudakinsky district showed a moderate resistance to yellow rust and a high resistance to brown rust. View Aegilops tauschii, collected in the Rudakinsky district had a high resistance to yellow and brown rust. Species Aegilops crassa to yellow and brown rust showed a reaction from moderate resistance - 30% to moderate susceptibility - 40%. As a result of the studies to assess the resistance of wheat varieties in Central Tajikistan, the cultivars Jaldak, Safedaki Gorchivin and Viyod, which had high resistance to yellow and brown rust, as well as Pamir and Surkhak varieties, showed moderate resistance.
Distinct varieties of wheat with high and moderate resistance to the pathogen of yellow rust can be used as parental forms for breeding new varieties of wheat. Studies on assessing the resistance of Aegilops species have shown that the species Aegilops triunciales has a high resistance to the pathogen of yellow rust. Species of Aegilops tauschii and Aegilops crassa, collected from the Hissar salt source, had moderate resistance to the pathogen. These species of Aegilops can be used in the selection of new varieties of wheat.
La Trobe University
Antony Gendall, Hans Daetwyler, Matthew Hayden
Wheat stem (Sr), leaf (Lr) and stripe (Yr) rust pathogens are among the most destructive fungal diseases threatening global wheat production. We utilized 2300 wheat accession including worldwide landraces, cultivars, breeding materials and 341 synthetic accessions backcrossed with three widely grown Australian cultivars (Annuello, Yitpi and Correll) to investigate rust resistance under wide environmental conditions. The germplasm was genotyped with 90K SNP chip, and was phenotyped for two seasons in three different environments against Sr and Lr and in four different environments against Yr. Different environments for each trait showed significant correlation with mean r values of 0.53, 0.23 and 0.66 for Lr, Sr and Yr; respectively. Single-trait genome wide association (GWAS) revealed several environment-specific QTL and multi-environmental QTL distributed on all chromosomes except 6D. Multi-trait GWAS confirmed a cluster of Yr QTL on chromosome 3B (within 8.3 cM) as well as a QTL for Sr and Lr on chromosome 3D. Linkage disequilibrium and comparative mapping showed that at least three Yr QTL exists within the 3B cluster including the durable rust resistance gene Sr2/Yr30. The same region was effective against Sr resistance but did not pass the stringent significant threshold in two environments. The 3D QTL was found mainly in the synthetic germplasm with Annuello background which is known to carry the Ag. elongatum 3D translocation carrying Sr24/Lr24 resistance gene. Interestingly, estimating the SNP effect using BayesR method showed that the correlation among the highest 5% QTL effects across environments were lower than that for the small effect QTL with differences in r values of 0.25 and 0.2 for Lr and Yr respectively. These results indicate the importance of small effect QTL that cannot be captured using GWAS in achieving durable rust resistance. The detected QTL in this study are useful resources for improving bread wheat resistance to rust diseases.
Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
Punam Singh Yadav, Ramesh Chand, Vinod Kumar Mishra, Uttam Kumar, Arun Kumar Joshi
The Sr2 gene has been used extensively in bread wheat improvement for durable stem rust resistance. Interestingly, the resistance of Sr2, associated with the pleotrophic gene Pbc expressed as pseudo-black chaff (PBC), is tightly linked with Yr30/Lr27/Pm genes conferring multiple disease resistance. The linkage map of chromosome 3BS revealed that Sr2 is 0.43cM away from lesion mimic (lm) locus. The RIL population (Yangmai#6 ? Sonalika) of 88 lines including parents where Sonalika carries Sr2 and lm while Yangmai#6 is deficient to both was evaluated for three years (2013-2016). The objective was to determine if this fragment is inherited as one unit and provides resistance to multiple diseases. Twenty four SSR markers distributed between 0.00 to 7.09cM on 3BS covering both Sr2 (5.57cM) and lm locus (6.0cM) were studied in the RIL population. Phenotyping was done for Sr2 associated PBC and lesion mimic along with disease severity for leaf rust, and spot blotch. Positive and significant correlations were observed between leaf stem rust resistance with Sr2 carrying PBC and lm. However, lines with lm either alone or with Sr2 (showing PBC) exhibited spot blotch susceptibility. The reverse situation does not hold not true where genotypes carrying Sr2 alone showed no correlation with spot blotch resistance. This indicates that the Sr2 complex is inherited as a single unit. Use of 24 SSR also suggest that Sr2 and lm loci are tightly linked and inherited together. The co-inheritance of Sr2 and lm ensures the stability and durability of rust resistance. However, the discouraging observation of spot blotch susceptibility due to lm gene suggests a limitation in achieving multiple disease resistance in environments where spot blotch is important. We identified two transgressive segregates in the population showing least expression of lm despite the presence of Sr2 and lm together.
Mohamed 5th University / ICARDA
Samir Alahmad, Ayed Al-Abdallat, Lee Hickey, Abdelkarim Filali-Maltouf, Bouchra Belkadi, Filippo Maria Bassi
Durum wheat (Triticum durum Desf.) is a major cereal crop grown globally. The terminal reduced moisture and heat occurring at the flowering phase are among the main constraints to its production. The molecular basis of tolerance to these threats remains mostly unknown. A subset of 100 genotypes derived from a collection of 384 accessions originating from different countries were investigated for their root growth and architecture under water-limited and well-watered treatments. Two protocols were used, "clear pot" for seminal root angle and "pasta strainer" for mature root angle evaluation. This study reveals that root architecture did not change depending on water treatment. A genotypic variation in root angle was found and two categories of root types were identified: genotypes with (i) superficial and (ii) deep rooting systems. In order to investigate the impact of each root type on yield, all genotypes were tested in the field at multiple locations and under different water regimes. The same set was also tested for heat tolerance in the field under rainfed conditions. Heat was imposed by placing a polytunnel at flowering time to raise the temperature of 10 degrees. The yield, thousand kernel weight and grain number per spike, were evaluated and compared to assess grain fertility, considered as a key trait of heat tolerance. The complete set was genotyped and a genome scan using 8173 SNPs markers developed by 35K Axiom array allowed to identify the genomic regions influencing drought and heat adaptation mechanisms. The pyramiding of this genomic regions could lead to an improved resilience to climate change and increase durum wheat productivity.
Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
Vinod Kumar Mishra, Uttam Kumar, Ramesh Chand, Akhilesh Mishra, Arun Joshi
Ug99 is a devastating race of Puccinia graminis f.sp. tritici possessing virulence against resistant genes Sr31 and Sr24. This race is highly adoptive and has spread quite rapidly with 13 known variants covering 13 different countries. For reducing the vulnerability of wheat in south Asia to the Ug99, breeding durable resistant varieties is important. India, second largest wheat producer, falls in the predicted pathway of Ug99. Most of the Indian germplasm possesses Sr31 and Sr24 in their background. HUW468, a well adopted variety of north eastern plains zone (NEPZ) of India, carries durable resistance gene Sr2. To strengthen it, a MABB program was initiated to introgressed two major genes (Sr50 and SrWeb) using a donor line PMBWIR4 from CIMMYT. The foreground selection was performed with Xgwm47 for SrWeb and IB267 for Sr50 followed by the background selection by using 128 polymorphic SSR markers covering all chromosomes. Backcross progenies of HUW468 were screened in the field condition by using of Pgt race 21A-2 at IARI, Regional Station, Indore located in the central India. Superior selected lines from BC2F4:5 generation was planted at three locations in India namely; Varanasi, Indore and Dharwad. HUW468-09-25-47-09 and HUW468-09-25-47-56 were selected from BC2F5 generation having Sr50 and SrWeb along with Sr2 gene, superior agronomic performance and with 93.5% and 92.7% genome recovery, respectively. These two lines also possess 6-10 % yield superiority over the recipient parent HUW468. These lines have been submitted for registration in NBPGR (National Bureau of Plant Genetic Resources), India.
Research Center of Agricultural and Development in Northwest Semi-arid regions of Tunisia
Afef,OTHMANI, Olfa, SLAMA-AYED, Hajer, SLIM-AMARA, Mongi, BEN YOUNES, , , , , , , , , , , , , , , , , , , , , ,
Eleven durum wheat (Triticum durum Desf.) genotypes were screened to select for drought-tolerance under in vitro immature embryos culture. Drought stress is induced by using five PEG concentrations (0, 200, 270, 295 and 310 g/l of PEG 6000). Results showed, for all studied traits, significant differences among PEG treatments and genotypes. In fact, increasing PEG concentration decreases relative growth rate, callus water content, relative water content, in vitro tolerance and relative tolerance. Biplot analysis indicated that the first two PCs (principal components 1 and 2) explain 70.5 % and showed that Karim, Mahmoudi and Om Rabiaa are respectively the most drought tolerant varieties tested, however, Ben Bechir, Maghrbi and Nasr were the most sensitive.