Bangladesh Agricultural Research Institute
Paritosh Kumar,Malaker, Krishna Kanta, Roy, Md. Mostofa Ali, Reza, Naresh Chandra Deb, Barma, Md., Farhad, , , , , , , , , , , , , , , , , , , ,
Leaf rust is one of the major diseases of wheat in Bangladesh. The farmer fields and trial sites were regularly surveyed for rust assessment from 2010-2011 to 2016-2017 wheat growing seasons. Disease severity was recorded following BGRI protocols. Percentage of fields infected with leaf rust and the levels of disease severity varied with genotype, year, planting time and survey sites. Timely planted wheat either escaped or had less disease compared to late planted crop. Among our cultivated varieties, Shatabdi was either free from infection or exhibited only trace severity with resistant reaction. Variety Saurav, Bijoy, BARI Gom 27 , BARI Gom 28 , BARI Gom-29 and BARI Gom-30 were consistently free from leaf rust infection. BARI Gom 25 and BARI Gom 26 showed low to moderate disease levels with MRMS-MSS reactions, while the variety Prodip demonstrated moderate to high disease severity with susceptible response and it needs to be replaced by resistant variety to sustain wheat productivity.
Mohamed 5 university/ICARDA
Amadou tidiane sall, meryem zaim, Ayed Al-abdallat, Gregor Gorjanc, Jesse Poland, Miloudi Nachit, Abdel karim Filali Maltouf, Bouchra Belkadi, Rodomiro Ortiz, Filippo Bassi
Durum wheat production is globally important, but grain yield has been stagnating in recent decades. In order to ensure that its production maintains the pace with increasing demand, breeding for high grain yield must be supported by molecular-based methods. Genomic estimated breeding values for selection and genome scan were assessed as molecular tools holding maximum potential for durum wheat breeding. Four recombinant inbred line populations bred by inter-mating elite were sown in yield trials at five sites. All progenies were characterized using "genotyping by sequencing" method. A consensus map was developed, and missing genotypes were imputed using a Hidden Markov model to reach a total of 1987 polymorphic markers. Models accounting for genotype environment interactions were used to estimate the genetic component of each measured trait. Hence, Bayesian ridge regression was used to determine the predicted values and their relative accuracy in several combinations, testing full-sibs and half-sibs as training population for grain yield and 1,000 kernel weight. The high level of accuracy achieved suggests that GEBV for selection holds great potential for durum wheat breeding, as long as full-sibs are used as training populations, in combination with statistical models that account for G?E. In order to test the exploitability of genome scan to guide breeding crosses, a separate genome-wide association study was conducted. 288 elite were sown in the south of Morocco and at two sites along the Senegal River for two years. These sites show a temperature differential of 10?C. Implementing a GE model facilitated identifying the most heat tolerant among the tested entries. 8,173 polymorphic SNPs were inquired, and several associations could be identified between markers and the ability to withstand the heat gradient. Hence, GWAS holds great potential to increase genetic gain in breeding via increased accuracy in determining the crosses to be made.
La Trobe University
Reem Joukhadar, Sukhwinder Singh, Francis Ogbonnaya
Synthetic hexaploid wheat (SHW), generated by crossing Triticum turgidum (AABB) with Aegilops tauschii (DD), has been exploited in improving various traits in cultivated wheat. A number of recent studies decomposed the additive variance of different traits captured by multiple sets of variants (e.g. single nucleotide polymorphisms (SNPs) located on different chromosomes or genic/intergenic regions) in both human and animal quantitative genetics studies. In this research, we dissected the additive variance explained by the three subgenomes and seven homoeologous sets of chromosomes in SHW germplasm to gain a better understanding of trait evolution in newly synthesized wheat. Our SHW germplasm lines generated by crossing improved durum parents (AABB) with Aegilops tauschii (DD) parents were phenotyped for ten fungal/nematode resistance traits. The lines were genotyped by genotyping-by-sequencing and 6,176 SNPs were mapped with missing data of less than 20%. The D subgenome dominated the additive effects and this dominance affected the A more than the B subgenome. The D subgenome exhibited a 1.8-fold higher contribution than the A subgenome across all traits. This dominance was not inflated by population structure or by longer linkage disequilibrium blocks observed in the D subgenome. The cumulative effects of the three homoeologs in each set had a significant positive correlation with their cumulative explained additive variance. Moreover, an average of 70% for each chromosomal group cumulative additive variance came from one homoeolog that had the highest explained variance within the group across all ten traits. We hypothesize that structural and functional changes during diploidization may explain chromosomal group relationships as allopolyploids maintain a balanced dosage for many genes. Our results contribute to a better understanding of trait evolutionary mechanisms in SHW, and will facilitate effective utilization of wheat relatives in breeding.
All Russian Research Institute of Biological Plant Protection
Irina Petrovna Matveeva
Yellow rust caused by Puccinia striiformis West. is a harmful and dangerous disease in the south of Russia. Yield losses under optimum conditions on highly susceptible varieties can vary from 10 to 100%. During the growing season of 2017, cool weather with constant precipitation from the third decade of April to the first decade of June contributed to the intensive development of the pathogen. Surveys of the main winter wheat production areas in five agroclimatic zones of the region revealed that yellow rust was prevalent in all areas. The maximum development of P.striiformis was observed in southern submontane and western Priazovsky agroclimatic zones. Some varieties such as Grom, Yuka, Tanya, Anka had losses to yellow rust of up to 30-40 %. In the central and northern agroclimatic zones, the losses averaged 5%, whereas in the dry eastern steppe zone losses were only up to 1%. The build up of yellow rust inoculum in the region raises concerns that in 2018, under favorable weather conditions in spring, winter wheat crops could be infected with the disease, especially in the wetter agroclimatic zones.
University of the Free State
Liezel Herselman, Botma Visser, Willem Boshoff, Zacharias Pretorius
Most South African winter wheat varieties display all stage resistance (ASR) to stem rust caused by Puccinia graminis f. sp. tritici (Pgt). To study inheritance, four resistant varieties were crossed to a susceptible parent (Line 37) and F2 populations were phenotyped at the seedling stage with stem rust race PTKST (Ug99 lineage). Populations derived from varieties Koonap, Komati, Limpopo and SST 387 segregated in a 3:1 ratio, indicating that a single, dominant gene confers resistance in each population. Assessment of F2 seedlings of four intercrosses between these varieties failed to deliver susceptible segregants therefore suggesting that they carry the same resistance gene. Genotyping of F2 plants with microsatellite markers produced consistent linkage of resistance with markers on chromosome 6DS. Experiments are underway to determine the relationship between resistance in the four winter wheat varieties and resistance genes Sr42, SrCad and SrTmp, all located on 6DS. Current evidence shows that ASR in the South African winter wheat varieties Koonap, Komati, Limpopo and SST 387 is based on a single gene and thus vulnerable to pathogenic adaptation in Pgt.
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.
National Research Centre
Food crisis is a major concern in Egypt, where drought and saline soils are ubiquitous. Wheat is a staple food in Egypt, which is only moderately tolerant to drought and salinity. Due to its rapidly increasing demand, there is an urgent need in Egypt to enhance wheat yields under drought and salinity conditions. Improving salinity or/and drought tolerance of genotypes is inhibited by a lack of efficient evaluation methods. High throughput precision phenotyping provides an innovative technology to screen for enhanced salt or drought tolerance from a large of number of genotypes under field conditions and can have immediate value to plant breeding. Therefore, we have tested several wheat phenotyping techniques i.e., canopy temperature (CT), spectral reflectance (SR), chlorophyll content (SPAD value), crop ground cover, relative water content (RWC), Water soluble carbohydrates (WSC), leaf area index (LAI), crop morphological traits, and grain wheat yield and yield components. We documented strong correlation/linear regression/polynomial regression between the wheat phenotyping techniques and in-season biomass/grain yield. It could be concluded that the documented results confirmed that several landraces were selected as drought/salinity tolerant out of 762 wheat landraces wheat were screened. Using high throughput precision phenotyping could provide an innovative technology and can have immediate value to plant breeding.
Crop Breeding Institute
Sripada Udupa, Charles Mutengwa, Peter Mavindidze
Host resistance is the most effective and economical method to minimize yield losses caused by rusts. The aim of this study was to detect the presence of resistance in 75 wheat genotypes. The presence of the genes viz. Sr2, Sr24, Lr34, Lr37, Lr46 and Lr68 was investigated using simple sequence repeat and sequence tagged site markers. Quantitative aspects of resistance to leaf rust were assessed through infection response (IR), disease severity (DS), coefficient of infection (CI), disease incidence (DI), leaf tip necrosis (Ltn) and area under disease progress curve (AUDPC) under natural epidemics. Highly significant (p <0.001) differences were observed among the genotypes for CI, DI, AUDPC and relative AUDPC (rAUDPC). Twenty genotypes exhibited high levels of adult plant resistance, recording CI less than 20% and AUDPC less than 300%, with moderately susceptible to susceptible reactions. The most frequently occurring gene was Lr46 (21%), followed by Lr68 (20%), Lr34 (19%) andLr37 (11%). The stem rust resistance gene Sr24 was absent in all the genotypes. Selection for Lr34 and Lr46 based on Ltn alone can sometimes be misleading because of its variable expression in different genetic backgrounds.
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.
Punjab Agricultural University
Parampreet,Kaur, Preeni, Bawa, Bharat, Yadav, Ajay, Mahato, Inderjit, Yadav, Priti, Sharma, OP, Gupta, Parveen, Chhuneja, NS, Bains, Jaroslav, Dolezel, Bikram Singh, Gill, J, Khurana, NK, Singh, Kuldeep, Singh, Kelly, Eversole
Diploid A genome wheat species harbor immense genetic variability which has been targeted and proven useful in wheat crop improvement. Further, the development and deployment of sequence based markers in wheat using survey sequences from next generation sequencing has opened avenues for comparative analysis, gene transfer and marker assisted selection (MAS) using high throughput cost effective genotyping techniques. Chromosome 2A of wheat is known to harbor several economically important genes. The present study aimed at in silico identification of genes corresponding to full length cDNAs and mining of SSRs and ISBPs from 2A draft sequence assembly of Chinese Spring for marker development. In totality, 1029 primer pairs (478 gene based, 501 SSRs and 50 ISBPs) were used to screen for polymorphism in diploid A genome species i.e., T. monococcum and T. boeoticum that identified 221 polymorphic loci. Out of these, 119 markers were mapped in T. monococcum X T. boeoticum RIL population. The enriched 2A genetic map constituted 161 mapped markers with final map length of 549.6 cM. Further, the utility of this enriched genetic map was demonstrated towards the fine mapping of adult plant resistance (APR) QTL, QYrtm.pau-2A against stripe rust. Using composite interval mapping, a QTL was detected between G45 and G54 markers explaining 19% of phenotypic variance. The primer sequences of the two genic markers were used to find the scaffold of 343 kb from IWGSC WGA V0.4 data. Thirty five simple sequence repeat markers were designed from the scaffold sequence which are being used for the fine mapping of QYrtm.pau-2A.