Department of Field Crops, Ege University, Izmir, Turkey
Kumarse Nazari, Mehran Patpour, Davinder Singh, Aladdin Hamwieh
Rust diseases in wheat are the major threat to wheat production and yield gains. The breakdown in resistance of certain major genes and new emerging aggressive races of rusts are causing serious concerns in all main wheat growing areas of the world. Therefore, it is the need of the hour to search for new sources of resistance genes or QTL's for effective utilization in future breeding programs. In total 100 wheat genotypes were evaluated for seedling and adult-plant resistance to stem rust races TKTTF and TTKSK at Tel Hadya-Syria, and Njoro-Kenya, and Kelardasht-Iran. Evaluation to Yr27 virulent stripe rust race was carried out at Tel Hadya and Terbol-Lebanon research stations. In this study we used genome wide association studies (GWAS) to identify markers or QTLs linked to stem rust and stripe rust races using Diversity Arrays Technology (DArT?) in selected 35 Iranian wheat genotypes. The association of markers and phenotypes was carried out using a unified mixed-model approach (MLM) as implemented in the genome association and prediction integrated tool (GAPIT). Out of 3,072 markers, 986 were polymorphic and used for marker trait associations. A total of 44 DArT markers were identified to be significantly (p<=0.01) associated with studied traits in 16 genomic regions 1A, 1B, 2A, 4A, 6A, 7A, 1B.1R, 2B, 3B, 4B, 5B, 5B.7B, 6B, 7D and an unknown region. Among associated markers, 34 were linked to stem and nine to stripe rust. They were found on 16 genomic regions on chromosome arms 1A, 1B, 2A, 4A, 6A, 7A, 1B.1R, 2B, 3B, 4B, 5B, 5B.7B, 6B, 7D and an unknown region. Associated markers explained phenotypic variation ranging from 21 to 65%. In addition to validation of previously identified genes, this study revealed new QTL's linked to stem and stripe rust which will assist breeders to develop new resistant varieties.
University of Minnesota, St. Paul, MN 55108, U.S.A
Ruth Dill-Macky, Ruth Wanyera, Sridhar Bhavani, Worku Bulbula, Matthew Rouse
Stem rust caused by Puccinia graminis f.sp. tritici (Pgt) is one of the major constraints to wheat (Triticum aestivum) production worldwide. Pgt races have rapidly evolved in several geographical regions due to the deployment of single resistance genes resulting in boom and bust cycles, hence combinations of resistance genes through pyramiding ensures durability of resistance in wheat varieties. Spring wheat line CI14275 displayed high levels of field resistance to stem rust in Kenya and USA compared to the parents in its pedigree (Thatcher, Kenya Farmer & Lee). To understand the genetics of resistance in CI14275, 114 Recombinant Inbred lines (RILs) were developed from the cross CI14275/LMPG-6 and screened for seedling response to Pgt races TTTTF, TPMKC, TRTTF, TTKSK & RTQQC. Chi-square goodness of fit tests suggested one-gene, three-genes, and four-genes segregated for response to races TTTTF, TPMKC and RTQQC, respectively. The RILs were all susceptible to races TTKSK and TRTTF. CI14275 showed intermediate low infection types only against races TPMKC (23-) and TTTTF (1+3C). Field screening of the population was completed in Kenya, Ethiopia and St. Paul where CI14275 showed high levels of resistance TMR (Kenya), 5MS (Ethiopia) and 5RMR (St. Paul) against the prevalent races in the stem rust screening platforms. LMPG-6 displayed susceptible responses ranging from 70S-90S in the three locations. 90K wheat Single Nucleotide Polymorphism (SNP) marker platform will be used to genotype parents and the population.
Cereal Crops Research Institute Pirsabak Nowshera, Pakistan
Khilwat Afridi, Muhammad Ishaq, Irfan Shah, Ibne Khalil, Masood Jan
The Cereal Crops Research Institute (CCRI) is situated on the left bank of River Kabul, near village Pirsabak, 3 km east of Nowshera at an elevation of 288 m above sea level on the intersection of 74? E longitude and 32? N latitude. In July 2010, a devastating flood destroyed all the available germplasm, machineries, laboratories, and field equipment. After the flood research activities were restarted with full motivation, dedication and hard work in collaboration with PARC, ICARDA, CIMMYT, and with the help of wheat productivity enhancement program (WPEP). Developed new population of wheat via spring x spring, spring x facultative germplasm to elevate genetic diversity and lines selected from segregating populations for high yield and rust resistance are at advanced stage of testing.
Since the flood, the CCRI developed four new wheat cultivars: Pirsabak-2013 Pakhtunkhwa-2015 for irrigated areas and Shahkar-2013 and Pirsabak-2015 for rainfed areas of Khyber Pakhtunkhwa, Pakistan. Varietal maintenance and seed production of the released varieties has been undertaken by the wheat breeding team effectively. The seed of these newly developed wheat cultivars was multiplied on fast track basis through pre-released seed multiplication and now these four varieties are the most popular cultivars of Khyber Pakhtunkhwa, Pakistan. Three new candidate wheat lines (PR-106, PR-110 and PR-112) have been submitted to provincial seed council for approval as new wheat cultivars for Khyber Pakhtunkhwa, Pakistan. Two new candidate lines i.e. PR-115 and PR-118 got first position in National Uniform Wheat Yield Trials (NUWYT) on the basis of grain yield during 2016-17 under irrigated and rainfed conditions, respectively.
Wheat Research Institute, AARI, Faisalabad, Pakistan
Ghulam Mahboob Subhani, Makhdoom Hussain, Mehvish Makhdoom
Rust is the single largest factor limiting wheat production in Pakistan. According to the FAO reports, countries in the predicted immediate pathway of Ug99 grow more than 65 million hectares of wheat, accounting for about 25% of global wheat harvest.
Rice, a member of the same family (Poaceae) is not attacked by any rusts. Wheat, an allo-hexaploid is responsive for wide crossing. It has previously been successfully crossed with its several wild relatives and different other crop species like corn, pearl millet etc. Based on the above facts wheat ? wild rice crossing has been attempted to incorporate rust resistance from rice to wheat. Successful crosses were made under in-vitro conditions. Surviving plantlets developed from these crosses were assayed for any genetic material introgressed from rice. Different cytological / molecular techniques were used to detect the introgression (Squash preparations from root tips, FISH, GISH, SSR etc.). Two hundred and fifty primers specific to rice chromatin were used to look for the introgression of rice chromatin into hybrids. Seven primers amplified the fragments in hybrids indicating the possible introgression of rice chromatin in wheat x rice hybrids but in-situ hybridization didn't confirm that introgression. So further testing of these hybrids is needed.
National Institute of Agriculture Research, Tunisia
Meeting food security challenges is a high priority in many developing countries. North African countries are among those with the highest per capita wheat consumption in the world and chronic grain deficits. Climate change scenarios predict decrease of rainfall and increase of temperature with negative impact on crop production and hence food security. Along with adoption of modern technologies, breeding higher yielding and more climate change resilient wheat varieties is widely seen as a tool that can sustain past yield gains and food production increases. Durum wheat production in Tunisia greatly benefited from the green revolution ingredients. Continued breeding lead to replacement of the early semi dwarf varieties with higher yielding, better disease resistant and more drought tolerant ones that have positively impacted yield at farmer and national level. Monitoring gains from increased yield potential and resistance to the most damaging foliar diseases, mainly septoria leaf blotch, leaf rust and stripe rust, showed that grain yield of recently released varieties is up to four times that of the tall late maturing landraces grown before the 1970's and up to 2.5 times that of varieties of the early years of the green revolution. Chlorophyll content, green leaf duration, deeper root development from diverse donors including wild wheat relatives and grain yield are being integrated in the breeding program for the selection of more drought and heat stress tolerant durum cultivars
INIA Uruguay and Dep. Plant Pathology, Kansas State University, US
Pierina Clerici, Richard Garcia, Fernando Pereira, Noelia Perez, Martin Quincke, Silvia German
Leaf rust (LR) and stem rust (SR) are threats to global wheat production and new races frequently overcome resistance genes deployed in wheat cultivars. Identification of new sources of resistance is a major goal for many pre-breeding programs. The objective of this study was to investigate the genetic basis of resistance to LR and SR in a diverse South American wheat panel. Molecular markers for known resistance genes and GBS were used to dissect genetic components. The wheat panel of 122 lines was characterized under field conditions at La Estanzuela Research Station, Uruguay, for disease severity (DS) to LR (2014 and 2015) and SR (2015), and LTN (leaf tip necrosis). Final DS for LR ranged between 0 and 95%, with mean values of 40% (2014) and 46% (2015). For SR, final DS ranged between 0 and 50%, with a mean value of 5%. The frequencies of positive diagnostic resistance markers among accessions were 20.5% for Lr34/Sr57, 6.6% for Lr68, 3.3% for Sr2/Lr27, 23% for Sr31/Lr26, 20.5% for Sr24/Lr24, 9.4% for Sr25/Lr19, and 0% for Sr39/Lr35. Of all the LR/SR resistance genes, only the effect of Lr68 was significant when predicting LR DS. Seventeen lines were identified with combinations of two genes, but no combination conferred a significantly improved level of resistance. Preliminary GWAS analysis for LR response on a subset of 86 lines revealed several QTLs, with a major QTL explained by Lr68. Lines with good levels of resistance to LR and SR, high expression of LTN, and absence of markers for the studied resistance genes were identified, indicating that there are other genes involved in resistance. Future research involving the testing of additional molecular markers for other known resistance genes, and a deeper GWAS analysis, will provide further information about the resistance genes present in this wheat panel.
University of the Free State, South Africa
Nelzo Ereful, Botma Visser, Lesley Boyd, Zakkie Pretorius
Adult plant resistance (APR) to stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is often conferred by multiple minor genes and has the potential to be durable. A preceding project identified two Kenyan wheat lines (W1406 and W6979) from the Genome Resource Unit (Norwich, UK) that exhibit APR to Pgt. The aim of this study was to investigate the APR response to Pgt race PTKST in W1406 and W6979 compared to 37-07, a susceptible control line. Histological investigation of inoculated flag leaf sheaths indicated a significant and quantifiable decrease in Pgt colony size in the APR lines at 120 hours post inoculation (hpi). Molecular analysis supported the observed fungal biomass decrease in the APR lines at 120 hpi. RNAseq analysis identified 169 transcripts differentially expressed in W1406 and 166 transcripts in W6979 when comparing 24 and 72 hpi to 0 hpi. In W1406 transcripts encoding putative pectinesterases, lipid-transfer proteins and leucine-rich repeat-like proteins were induced at 72 hpi. In W6979 only a corresponding putative pectinesterase encoding transcript was identified. Although the induced defence response in the two APR lines exhibited some dissimilarity, it potentially involves cell wall modification in both lines. Two independent sets of peroxidases were induced at 24 and 72 hpi in both lines, suggesting independent signalling events. Expression analysis suggests the occurrence of two phases of gene expression, one at 24 hpi and another at 72 hpi; the latter seeming to correspond to the inhibition of Pgt growth, manifesting as the observed APR phenotype.
Department of Agriculture, Sunsari, Nepal
Wheat (Triticum aestivum L.) is one of the major cereal crops vital for global food supply. Most of the wheat crop in developing world including that of Nepal is either grown with limited irrigation or under rainfed conditions and thus face moisture stress at one or more growth stages limiting grain yield. An experiment was carried out at the Institute of Agriculture and Animal Science, Rampur to evaluate the genetic variability of selected drought adaptive traits in Nepalese wheat germplasm. The wheat genotypes evaluated comprised of Nepalese landraces and commercial cultivars, CIMMYT (International Center for Maize and Wheat Improvement) derived advanced introduction lines and three checks with differential drought adaptability. The wheat genotypes were grown in pots (single plant) arranged in a replicated split plot design in greenhouse under two contrasting moisture regimes, optimum and moisture stressed. The genotypes were evaluated for water use, water use efficiency, relative leaf water content and biomass production. The ANOVA (Analysis of Variance) revealed significant variation between environments and among the wheat genotypes for most of the traits studied. A wide range of variability was observed for water use, water use efficiency, biomass yield and relative leaf water content in moisture stressed and non-stressed environments. Nepalese cultivar Gautam showed a number of favorable drought adaptive traits, whereas, Bhrikuti was average in this respect. Based on the scores of drought adaptive traits recently released Cultivar (cv). Vijay was characterized as drought sensitive. A number of landraces and advanced breeding lines showed high level of water use efficiency and other positive traits for drought adaptation.
Jamal El Haddoury, Ahmed Amri
Malika', a hard red spring wheat (Triticum aestivum L.) cultivar developed using doubled haploid technology by the Institut National de la Recherche Agronomique (INRA), Morocco, and tested as 06DHBW48, was approved for release in 2016 by the Office National de S?curit? Sanitaire des Produits Alimentaires (ONSSA), Morocco. Malika was selected from the doubled haploids derived from the cross 'Achtar3*//'Kanz'/Ks85-8-4). Achtar and Kanz are Moroccan varieties originating from segregating populations from CIMMYT. Achtar and Kanz are a well adapted to Moroccan conditions but susceptible to the Hessian fly, yellow rusts and some races of leaf rust. 'Achtar' was crossed with it in order to incorporate the Hessian fly resistance, yellow rust resistance and leaf rust resistance and 'Achtar' was crossed with Kanz/Ks85-8-4 having resistance to Hessian fly, yellow rust and leaf rust. Backcrossed 3 times with 'Achtar', and selected lines having resistance to the Hessian fly, yellow rust and leaf rust from the population derived from each backcross. Finally the selected the resistant line was used develop doubled haploids. The doubled haploid lines produced were tested in the laboratory and field for Hessian fly and the rust resistance. The resistant lines were incorporated in the multi-local yield trials and three promising lines with the resistance to Hessian fly, yellow rust and leaf rust and better yield and quality were submitted for registration in the official catalog in 2014. After 2 years of testing (years 2014-15 and 2015-16), one line (06DHBW48) was accepted for the registration and designated as 'Malika'. 'Malika' is a semi-dwarf variety, well adapted to semi-arid regions, early maturing, high yielding, tolerant to drought and resistant to Hessian fly, leaf rust and yellow rust.
Lake Chad Research Institute, Maiduguri, Borno State-Nigeria
Dattijo Aminu, Zakari Goji Silas Turaki, Fatima Henkrar, Udupa Sripada
The research was conducted at ICARDA, Rabat. Twenty-four accessions were obtained from LCRI for marker analysis. Wizard Genomic DNA Purification Kit was used for DNA extraction. DNA was extracted by CTAB method and quantified using 1.0 % (w/v) agarose gels. Total of 12 loci, 5 functional and 7 linked random DNA markers to the traits of interest were used. PowerMarker and DARwin software were used to calculate the No. of alleles and values of genetic diversity, PIC, genetic distance, and NJ dendrogram. The total No. of detected alleles was 39; and mean No. of alleles was 3.25. No. of alleles range from 1 (Dreb-B1) to 9 (Xgwm577). Genetic diversity index ranged from 0.0000 in Dreb-B1 to 0.8471 in Xgwm577. The PIC value was also varied from 0.0000 (Dreb-B1) to 0.8296 (Xgwm577). The frequency of biotic resistance linked random DNA marker allele at Xgwm144 and Xwmc44, associated with yellow and leaf rust gene was 25% each. Marker alleles Xgwm577 and Xgwm533 linked to Stb2 and Stb8 at 150 and 120bp have frequencies of 21 and 4%. The frequency of abiotic resistance showed 50% of accessions had 1R segment (1BL.1RS translocation) and 58% of accessions showed presence of 120bp allele of Xwmc89, associated with QTL for drought tolerant. Functional marker alleles of Dreb-B1 associated with drought tolerant genes showed alleles frequency in all accessions. Linked marker allele Xgwm111 linked to heat tolerant gene showed 17% allele frequency at 220bp. Rht1 and Rht2, the allele frequencies were 92 and 4%. 92% of the cultivars had photoperiod insensitive allele at Ppd-D1 locus. VrnA1a and VrnA1c primer pair amplified at 965, 876, and 484bp, allele frequency of 13 and 87%. Cluster analysis had grouped the accessions into 5 at a genetic distance level 0.15.