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.
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.
Agricultural Biotechnology Research Institute, Ayub Agricultural Research Institute (AARI), Faisalabad-Pakistan
Imran Habib, Sajid-ur-Rahman, Muuhammad Waqas Jamil, Muhammad Zaffar Iqbal
Rust diseases are among the most important affecting wheat because they are responsible for a significant yield reduction globally. Different types of conventional breeding approaches are currently underway to protect wheat from these diseases. The involvement of molecular genetics and biotechnology tools in conventional plant breeding sets new directions to develop crop varieties with desired traits more efficiently and accurately. An array of molecular markers linked to rust resistant genes and dense molecular genetic maps are now available for use. Marker assisted selection (MAS) is now a routine activity in various crops especially for agronomic traits that are otherwise difficult to tag like resistance to pathogens, insects, nematodes etc. Gene pyramiding involves the stacking of many genes leading to real-time expression of all genes in single variety to develop durable resistance. This method is gaining significant popularity as it would enhance the efficiency of conventional breeding methods and precise development of broad spectrum resistant capabilities. Keeping in view the significance of MAS, rust resistant wheat parental lines were selected and molecular information was tagged using gene linked markers through PCR. Conventional breeding plane was designed on the basis of molecular data and maximum crosses were made between high yielding susceptible and resistant wheat genotypes. Molecular screening and other yield parameters were keenly noted on each stage of segregating population. Three rust resistant genes i.e. Lr-34/Yr-18, Lr-46/Yr-29 and Lr-19 were successfully combined in three cross combinations. Twenty crosses were found positive for two resistant genes i.e. Lr-46/Yr-29 and Lr-19, Moreover, one cross was positive for Lr-34/Yr-18 and Lr-46/Yr-29, and one was positive for Lr-34/Yr-18 and Lr-19. Introduction of more genes is also continued to develop superior resistance against a wide range of rust pathogen in wheat.
Sher-e-kashmir University of Agricultural Sciences and Technology of Kashmir, Jammu and kashmir, India
Reyazul Rouf Mir, Shazia Mukhtar, Rahul R., Nelwadker, M., Ashraf Bhat
In India stripe rust of wheat (Triticum aestivum L.) is important as it occurs in the severe form in North Hill Zone (NHZ) covering states of Jammu and Kashmir, Himachal Pradesh and Uttarakhand. Stripe rust thrives well under cool and moist field conditions and sometimes its epidemic is so severe that it destroys the whole crop. Although the fungicides have been applied to control this disease but their use is unfriendly to the environment and they add to the input cost of farmers. The breeding for disease resistance is an effective strategy and involves identification of stable sources of resistance and their utilization. Deployment of yellow resistance genes has helped in suppressing the intensity, effectiveness and frequency of rust epiphytotics. Many sources of yellow rust resistance exist, but these are either incompletely characterized or these have not been studied in sufficient detail needed for their designation. The present study was conducted to screen for yellow rust resistance a set of 300 wheat germplasm lines received from various national and international germplasm centers viz., CIMMYT, Mexico; CIMMYT, Ankara, Turkey; IARI sub-station, Wellington, Tamil Nadu; IIWBR, Karnal; IIWBR, Flowerdale, Shimla and SKUAST-Kashmir, Srinagar for yellow rust resistance (46S119 and 78S84 as most prevalent races) over years 2012 to 2016 under field and ployhouse conditions. The study could identify eleven wheat lines showing varying levels of resistance to yellow rust races 46S119 and 78S84 when scored at adult plant stage under both conditions. The area under disease progress curve (AUDPC) scores of the lines identified as resistant was lowest as compared to yellow rust susceptible check (Agra Local). The resistant lines identified in the study could efficiently be utilized in yellow rust breeding programmes of the country and thereby deployment of such genes over space and time for an effective and long lasting control.
Instituto Nacional de Investigaci?n Agropecuaria (INIA)
Clara,Pritsch, Gustavo, Azzimonti, Silvia, Pereyra, Mart?n, Quincke, Victoria, Bonnecarrere, Paula, Silva, Ariel, Castro, Bettina, Lado, Silvina, Bar?ibar, Richard, Garc?a, Silvia, Germ?n, , , , , , , ,
Stem rust (SR) and Fusarium head blight (FHB) threaten the sustainability of wheat production worldwide. Sr2 is a widely used gene conferring partial, but durable, resistance to SR. Fhb1 confers a significant level of FHB resistance, but is poorly represented in the INIA-Uruguay wheat-breeding program. Sr2 and Fhb1 are linked in repulsion (~3 cM apart) on chromosome 3B. However, lines with Sr2 and Fhb1 in coupling were recently developed at the University of Minnesota, USA (kindly provided by J. Anderson). In order to incorporate Sr2/Fhb1 into Uruguayan elite wheat cultivars the donor line was crossed and backcrossed with four cultivars lacking both genes and expressing an intermediate to low level of resistance to SR and FHB: G?nesis 2375, G?nesis 6.87, INIA Madrugador, and INIA Don Alberto. Genotypes carrying Sr2/Fhb1 were selected using molecular marker UMN10; 250 BC2F1 were obtained for each recurrent parent. BC3F1 plants positive for UMN10 will be selected. The effect of Sr2/Fhb1 on response to SR and FHB in the different genetic backgrounds will be quantified by comparing disease severities of BC3F2 homozygotes with and without the UMN10 marker. Hopefully the introduction of Sr2/Fhb1 will contribute in reducing the risk of SR and FHB in wheat crops in Uruguay.
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.
Plant Pathology Division, Nepal Agricultural Research Council
Baidya Nath Mahto, Durba Bahadur, Thapa Roshan, Basnet Nautan Raj, Gautam Sesh, Raman Upadhyaya
Disease surveillance is very important in establishing the status of disease response in crops. During the 2014 to 2016 wheat seasons, foliar blight (spot blotch caused by Bipolaris sorokiniana and tan spot caused by Pyrenophora tritici-repentis) was recorded as severe across the entire whole plains region. Foliar blight was moderate in the mid hills, especially the Kathmandu valley. Leaf rust was severe (10MS - 100S) at several places in the mid hills. This could be due either to climatic conditions or varieties susceptible to the prevailing pathotypes. Yellow rust was also recorded up to 100S in the Kathmandu valley. Newly released varieties Gaura and Dhaulagiri showed yellow rust incidence of 20MS to 40S. Stem rust was sporadic and light and was observed very late in the season (tR - 10MR) in far western districts and the Kathmandu valley. Powdery mildew was moderate and localized. Loose smut was found at low levels throughout the mid hills. In 2014, Karnal bunt (caused by Tilletia indica) was also recorded in far western regions. Five different pathotypes of P. triticina (121R63-1, 21R55, 21R63 and 0R9) and one Pst pathotype (110S119) have prevailed during the last few years. Wheat genotypes were evaluated at Khumaltar and those reputed to have Yr27, Yr27+, Yr27+Yr18, Yr31+APR, Yr9, Yr10 and Yr15 were resistant. Similarly, genotypes containing Lr34+ had lower leaf rust severities than others.
Umesh Rosyara, Suchismita Mondal, Ravi Singh, Susanne Dreisigacker
Grain yield is the most important economic trait in wheat breeding. The detailed understanding of the genetic architecture of grain yield is crucial and the determining factor to optimize genomics-assisted selection strategies in wheat. First, we performed a marker and haplotype-based genome-wide association study (GWAS) for grain yield (GY) and yield stability coefficient (Pi) on 4,302 advanced breeding lines from five CIMMYT international bread wheat trails grown in multiple (optimally irrigated and stress) environments. All lines were genotyped using genotyping-by-sequencing. A haplotype map was built based on linkage disequilibrium between markers. Twenty-nine markers and 16 haplotypes were associated with GY and Pi across two and three germplasm trials with allelic effects ranging from 2 to 11% across environments. Secondly, we performed genomic prediction, testing eight different prediction models incorporating single markers (base model), haplotypes, epistatic interactions, and significant markers/haplotypes identified in GWAS. Initial results show that by including haplotypes and epistatic interactions among haplotypes (main effect and genome-wide), prediction accuracies range between 0.33-0.49 for GY, a 3 to 22.5% improvement over the base model. Despite the identification of significant marker/haplotype trait associations across traits and environments in GWAS, accounting for these markers in genomic prediction does not improve the prediction models. Our results suggest that the haplotype-based approach can increase prediction ability, but that the knowledge of the genetic architecture of grain yield might not have significant consequence on genomic-assisted selection.