University of Hohenheim, Germany
Afrem,Issa, Helim, Youssef, Nawzad, Suleiman, Abdul Rahman, Issa, , , , , , , , , , , , , , , , , , , , , ,
Wheat is grown in Syria during the November-December. Wheat is exposed to many strains that negatively affect its productivity especially rust diseases, which was reported on wheat in Syria for many years and the most severe in 2010, Therefore, we studied the effect of planting dates on the severity and development of yellow rust disease. Where the field trials of the 2010-2011 season were carried out at the two locations in northeastern of Syria: Al-Qamishli Research Center and Yanbouh Research Station in Al-Malekia. By cultivating the susceptible bread wheat Cham 8, where six dates were planted starting from 02.10. 2010, a difference of 15 days. The results showed there was a difference in the severity of the yellow rust disease according to the dates of cultivation and thus the stages of growth in the plant and this was evident in the Yanbouh location where the onset of the onset of injury on 08.04.2011 in the all dates and developed the infection to 40S degrees and 30%. Also, on the 24. 04. 2011, the infection was recorded at the Qamishli location only on the third and fourth dates. The disease did not develop more than 10S and 10% due to climatic conditions due to rain and high temperature during the season. The results showed a positive correlation between the evolution of the disease and vegetative growth of plants, where the growth of plants was more active at the site of Yanbouh, especially in the second, third and fourth dates in the development of infection on plants in the rest of the dates because of weak and slow growth of plants.
National Agronomic Institute of Tunisia
FATMA,BEN JEMAA, HAJER, SLIM-AMARA, , , , , , , , , , , , , , , , , , , , , , , , , ,
Wild species with valuable genetic heritage was used long time ago in interspecific crosses to improve cultivated plants adaptation to environmental constraints. The objective of this study is to transfer the salinity tolerance of Hordeum marinum, a wild barley species, to three durum wheat varieties (Karim, Razzek and Nasr) by intergeneric crosses. In order to skip the incompatibility between these species, in vitro immature embryo rescue was performed using B5 medium (Gamborg et al., 1968). The results showed that the genotype has an important effect on the success of the crosses and the rate of regenerated plants. We have found that 34.21% of the embryos derived from hybridization Razzek x Hordeum marinum has regenerated haploid plantlets, 5.88% for Karim x Hordeum marinum cross, and 2.78% for Nasr x Hordeum marinum.
The obtained chromosomal stock of the hybrid haploid plants was doubled by colchicine treatment concentrated at 0.05%. The rate of doubled haploid plants were reduced after colchicine treatment to 26.32% for Razzek x Hordeum marinum cross, 0% for Karim crossed with Hordeum marinum and remained unchanged for Nasr x Hordeum marinum.
The doubled haploids obtained are subjected to salt stress (6-12 g/l) in order to evaluate their tolerance to salinity.
Filippo,Bassi, Rodomiro, Ortiz, Ibrahima, Ndoye, AbdelKarim, Filali-Maltouf, Bouchra, Belkadi, Miloudi, Nachit, Michel, Baum, Hafssa, Kabbaj, Habibou, Gueye, Madiama, Cisse, , , , , , , , , ,
Wheat is a major food crop in West Africa, but its production is significantly affected by severe heat. Unfortunately, these types of high temperatures are also becoming frequent in other regions where wheat is commonly grown. In an attempt to improve durum wheat tolerance to heat, a collection of 287 elite breeding lines, including several from both ICARDA and CIMMYT, was assessed for response to heat stress in two irrigated sites along the Senegal River: Fanaye, Senegal and Kaedi, Mauritania during 2014-2015, and 2015-2016 winter seasons. The maximum recorded grain yield was 5t ha-1, which was achieved after just 90 days from sowing to harvesting. Phenological traits (heading, maturity and grain filling period) and yield components (1000-kernel weight, spike density and biomass) had also large phenotypic variation and a significant effect on grain yield performance. This panel was genotyped by 35K Axiom to generate 8,173 polymorphic SNPs. Genomic scans identified a total of 34 significant association between single nucleotide polymorphisms (SNPs) and traits across the four environments, including 15 related to phenological adaptation, 12 controlling grain yield components, and seven linked to grain yield per se. The identification of these genomic regions can now be used to design targeted crosses to pyramid heat tolerance quantitative trait loci (QTL), while the SNPs underlying these QTL can be deployed to accelerate selection process facilitated by DNA-aided breeding.
The University of Agriculture, Peshawar, Pakistan
Muhammad,Khan, Sangay, Tshewang, Sarala, Lohani, David, Hodson, Muhammad, Imtiaz, Sajid, Ali, , , , , , , , , , , , , , , , , ,
The Himalayan region of Pakistan and China has been shown to be the centre of diversity of Puccinia striiformis, however, little is known about the Eastern part of the Himalayas. We studied the genetic structure of P. striiformis from Nepal and Bhutan in comparison with Pakistan through microsatellite genotyping of 66 isolates from Nepal (35 isolates) and Bhutan (31 isolates) collected during 2015 and 2016. Genetic analyses revealed a recombinant and highly diverse population structure in Bhutan and Nepal. A high level of genotypic diversity was observed for both Bhutan (0.92) and Nepal (0.67) with the detection of 53 distinct multilocus genotypes (MLGs) in the overall population; 28 for Bhutan and 27 for Nepal. Mean number of alleles per locus was higher in Bhutan (3.33) than Nepal (3.11), while the gene diversity was higher in Nepal (0.4279) than Bhutan (0.3552). A non-significant difference between the observed and the expected heterozygosity in both populations further confirmed the recombinant structure. Analyses of population subdivision revealed a low divergence between Nepal and Bhutan (FST=0.1009), along with the detection of certain common MLGs in both populations. The overall population was clearly divided into six genetic groups, with no geographical structure, confirmed by the distribution of multilocus genotypes over two countries, suggesting a potential role of migration. Comparison with the Pakistani P. striiformis population suggested a high genotypic diversity in Nepal (0.933) and Bhutan (0.959), though lower than the previously reported from Himalayan region of Pakistan (Mansehra; 0.997). The overall high diversity and recombination signature suggested the potential role of recombination in the eastern Himalayan region (Nepal and Bhutan), which needs to be considered during host resistance deployment and in the context of aerial dispersal of the pathogen.
Nepal Agricultural Research Council, National Agriculture Genetic Resources Centre, Khumaltar, Lalitpur
Baidhya Nath,Mahto, Mina Nath, Paudel, Dhruba Bahadur, Thapa, Krishnahari, Ghimire, Bal Krishna, Joshi, Suraj, Baidya, Prem Bahadur, Magar, , , , , , , , , , , , , , , ,
Naked barley (Hordeum vulgare var. nudum L.), is an important winter crop grown in the mountain region of Nepal. Stripe rust (Puccinia striiformis f.sp. hordei), is the most destructive fungal disease of barley in the hills of Nepal with losses up to 100 %, occurring in cooler regions with higher altitude (1000-2500 m). Yield components along with final rust severity (FRS), area under disease progress curve (AUDPC) and average coefficient of infection (ACI) were evaluated for 20 indigenous barley accessions collected from mountainous region of Nepal at National Agriculture Genetic Resource Centre (Genebank), Khumaltar, Nepal during winter season of 2016-2017 with three replications. Barley cultivars displayed a range of severity from 0% to 100% with immune to susceptible reaction. AUDPC values were significantly different among the tested genotypes. Barley genotypes with accession number NGRC00837 (ACI-3), NGRC02357 (ACI-7), NGRC06026 (ACI-9) and NGRC02306 (ACI-12) were found resistant with lowest diseases progress while NGRC02350 (ACI-60), NGRC06036 (ACI-80), NGRC02312 (ACI-86), NGRC04003 (ACI-83) and NGRC02318 (ACI-93) were found as highly susceptible landraces. Correlation coefficients of agronomical parameters such as grains per spike and 1000-kernels weight with epidemiological parameters such as AUDPC and ACI were found highly significant. Resistant genotypes with low values for disease progress as well as diseases reaction were identified. The results indicate that source of resistance to yellow rust in naked barley genotypes are available in Nepal and can be used for resistant breeding in future.
University of the Free State
Gerrie Booysen, Willem Boshoff, Jozua Joubert
Urediniospores of rust fungi can be applied to cereal plants in several ways. Depending on the objective and available infrastructure, plants can be inoculated with a suspension of spores in either water, light mineral oil (e.g. Soltrol 130®) or engineered fluid (e.g. Novec 7100®). Alternatively, dry spores can be allowed to settle on plant surfaces by dusting or directly applied with a spatula or small brush. Several rust laboratories employ a system where a spore-oil suspension, contained in a gelatin capsule, is sprayed onto seedling leaves by means of a dedicated atomizer connected to an air pressure source. Although this approach is easy to use and highly efficient, the devices are not commercially available in South Africa. Locally, these inoculation appliances need to be manufactured by a conventional milling process that requires a specialized workshop and skilled personnel. This subtractive process is labour intensive and greatly prohibitive in terms of costs. Using a process called Additive Manufacturing (AM), also known as "3D printing", the body of an inoculator was digitally designed and then laser sintered in nylon. Loose powder was removed from flow channels by compressed air. A copper tube fitted afterwards connected the nylon body with the spore suspension in the capsule. Replicated inoculation tests of wheat seedlings with urediniospore bulks or single pustule collections of Puccinia triticina and P. graminis f. sp. tritici resulted in consistent levels of rust severity and infection frequency. Cleaning of inoculators in acetone for 1 min followed by a 1 h heat treatment at 60°C produced no contaminant infection in follow-up tests. The design has been registered in South Africa, the USA and Europe.
School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana-141004 India
Rohtas,Singh, Satinder, Kaur, Parveen, Chhuneja, , , , , , , , , , , , , , , , , , , , , , , ,
Leaf rust caused by Puccinia triticina is one of the most historical and economically important wheat diseases. Breeding for new cultivars with effective gene combinations is the most promising approach for reducing losses due to leaf rust. Wild emmer wheat, Triticum dicoccoides, the progenitor of modern tetraploid and hexaploid wheats, is an important resource for new variability for disease resistance genes. An accession of T. dicoccoides acc. pau4656 showed resistance against prevailing leaf rust races in India, when tested at the seedling and adult plant stage. The introgression line, developed from the cross of the leaf rust resistant T. dicoccoides acc. pau4656 and the susceptible T. durum cultivar Bijaga yellow, was crossed with T. durum cultivar PBW114 to generate recombinant inbred lines (RIL) for mapping leaf rust resistance gene(s). RIL population was screened against highly virulent leaf rust race 77-5 at seedling stage and inheritance analyses revealed the segregation of two leaf rust resistance genes. The genes have been temporarily designated as LrD1 and LrD2. A set of 387 SSR marker was used for bulked segregant analysis (BSA). The markers showing diagnostic polymorphism in the resistant and susceptible bulks were amplified on whole of the population. Single marker analysis using MapDisto software placed LrD1 on the long arm of chromosome 6A linked to the SSR marker Xwmc256 and LrD2 on long arm of chromosome 2A close to the SSR marker Xwmc632. T. durum cv. PBW114 used in the present study was also resistant to leaf rust at the seedling stage. So one of these leaf rust resistance genes might have been contributed by the PBW114 and other by T. dicoccoides. The current study identified valuable leaf rust resistance genes for deployment in wheat breeding programme.
University of Mohammed V/ICARDA
HAFSSA,KABBAJ, AYED, AL ABDALLAT, GREGOR, GORJANC, JESSE, POLAND, MIKAEL, MILOUDI NACHIT, AHMED, AMRI, BOUCHRA, BELKADI, KARIM, FILALI MALTOUF, FILIPPO, BASSI MARIA, , , , , , , , , , , ,
Durum wheat (Triticum durum Desf.) is a major stable crop and it represents a base of the Mediterranean diet. This region is subject to a Mediterranean climate, which is extremely unpredictable with severe changes in moisture and temperature occurring each crop season. This unpredictability is summarized by breeders as GxE and the identification of traits controlling this interaction is quintessential to ensure stability in production season after season. To study the genetics of yield stability, four RILs populations derived from elite x elite crosses were assessed for yield and 1,000-kernel weights across five diverging environments in Morocco and Lebanon. These 550 RILs were characterized with 4,909 polymorphic SNPs via genotyping by sequencing. A consensus map was derived by merging the individual genetic maps of each population. Finally, imputation was used to fill all the missing haplotypes and reach a reduction of missing data to below 8%. Several significant QTLs were identified to be linked to TKW, grain yield and a stability index, namely AMMI wide adaptation index (AWAI). A second approach to identify loci controlling stability was the use of a global panel of 288 elites, accessions and landraces tested in 15 diverging environment. Multi-locations data were compiled via GxE models to derive the AWAI stability index. In addition, this panel was characterized with 8,173 polymorphic SNPs via Axiom 35K array. Significant associations were identified for all traits, including QTLs unique to AWAI. The sum of the identified QTLs can now be pyramid via marker assisted selection and molecular designed crosses in order to obtain very stable cultivars.
Agharkar Research Institute Pune
yashavantha kumar,Kakanur, Shrikanth, Khairnar, Balgounda, Honrao, Vijendra, Baviskar, Ajit, Chavan, Vitthal, Gite, Deepak, Bankar, Sameer, Raskar, Satish chandra, Misra, , , , , , , , , , , ,
Heat stress globally remains the most important factor determining yield anomalies. Terminal heat stress shortens the duration of grain filling. Hence, this investigation was undertaken during the cropping season 2016-17 to evaluate heat stress tolerance of 32 bread wheat genotypes planted in timely (optimal temperature) and late (terminal heat stress) sown condition at Agharkar Research Institute, Pune. Data were collected and analyzed for various agronomical and physiological traits and also selection indices for stress tolerance, derived from grain yield of wheat genotypes under optimal and late sowing conditions. It was observed that the genotypes DBW 187, GW 477, HD 2932, DBW 107, PBW 752 were the highest yielding under timely sown condition whereas, HD 3226, DBW 187, HP 1963, HD 3219, DBW 196 were the highest yielding under late sown condition. DBW 187 was found to withstand the stress conditions. Minimum percent yield decrease and high yield stability index (YSI) was found in HD 3219 followed by HD 3226 and DBW 196 which indicated their better performance under stress condition. Harmonic mean, a stress tolerance selection index was found to be the best fit of linear model (R2 = 0.78) and a good indicator of high yield under heat stress condition. Physiological parameters, Chlorophyll (SPAD), canopy temperature (Infra-red thermometer) and vegetation index (NDVI) have not shown significant relation with yield, however, they were found to be significantly associated with yield contributing traits like biomass, thousand grain weight, grain number per spike. DBW 187 and HP 1963 showed stable yields with high PCA 1 and low PCA 2, indicating their resilience to stress conditions. The investigation has resulted in identification of genotypes for terminal heat stress conditions and also given greater insights in understanding the importance of physiological traits and stress tolerance indices in selection process.
University of Georgia
Mohamed,Mergoum, Yuanfeng, Hao, Jerry, Johnson, Dan, Bland, James, Buck, John, Youmans, Benzamin, Lopez, Steve, Sutton, Zhenbang, Chen, , , , , , , , , , , ,
Leaf rust disease, caused by the fungal pathogen Puccinia tritcina, is the most destructive foliar disease of wheat worldwide. Gene combination of Lr37/Yr17/Sr38 has been used in Georgia (GA) to prevent the loss from leaf rust; however, with the emergence of new virulent races, these genes have lost their effectiveness. 'AGS 2000' and 'Pioneer 26R61' are the most common soft red winter wheat (SRWW) cultivars in Southeastern US, and have been used as good sources of resistance to leaf and stripe rusts, and powdery mildew. To characterize the genetic basic of resistance of AGS 2000, a mapping population of 178 recombinant inbred lines (RIL) has been developed from a cross with Pioneer 26R61. This population was genotyped using a combination of SSR, DArT, and SNP markers, and a total of 2734 markers covering the entire genome were used for the construction of genetic map. Phenotypic evaluation of parents and RIL population was conducted at the seedling stage using a virulent GA leaf rust race. QTL mapping revealed a major QTL on chromosome 2BL, explaining about 20% of total phenotypic variation in AGS 2000. Additionally, a minor QTL was also detected on chromosome 5B. QTL on 2BL was identified as a novel gene, and can be used in marker-assisted selection for leaf rust resistance.