Rust reactions of wheat lines developed by another culture
Central Research Institute for Field Crops, Turkey
Turkey is an important producer of bread wheat. Fungal diseases, including the rusts, limit production. Resistant varieties are the main strategy for rust control. In this study 33 doubled haploid lines developed by anther culture and 9 standard cultivars were evaluated for seedling (YR, LR, and SR) and adult plant reactions (YR) to rusts at the Central Research Institute for Field Crops at Yenimahalle and Ikızce in 2014. For adult plant reactions the genotypes were inoculated with local Pst populations (virulent on differentials with Yr2 Yr6, Yr7, Yr8, Yr9, Yr25, Yr27, YrSd, YrSu, and YrA). Stripe rust development on each entry was scored on the modified Cobb scale when the susceptible check Little Club reached 80S disease severity in June 2014. Coefficients of infection below 20 were considered to be resistant. Seedlings were inoculated with local Pgt (avirulent on differentials with Sr24, Sr26, Sr27 and Sr31), Pt (avirulent on differentials with Lr9, Lr19, Lr24 and Lr28) and the Pst population. Seedling reactions were recorded 14 days post inoculation on either 0-4 (SR and LR) or 0-9 (YR) scales. Thirteen (33%), 2 (5%) and 9 (23%) genotypes were resistant to SR, LR and YR, respectively. Fifteen (38%) genotypes were resistant to stripe rust at the adult stage.
Up scaling seed of Ug99 resistant wheat varieties to ensure protection against stem rust in Pakistan
International Maize and Wheat Improvement Center (CIMMYT) Pakistan Office
With ongoing threats of rust from both internal and international sources it has become a priority at CIMMYT and for Pakistan national programs to accelerate the rate of seed increase and to popularize new Pgt race Ug99 resistant varieties to avert future disasters. Seed of Ug99 resistant varieties NARC-11, Pak-2013, Dharabi-2011 and BARS-09 was produced under the Wheat Productivity Enhancement Program (WPEP). The country-wide participatory approach involves a partnership of farmers, seed companies and research institutes. In 2014 16,020 and 6,085 kg of seed of NARC-11 and Pak-13, respectively, were distributed all over the country, including Azad Jammu Kashmir and Gilgit-Baltistan. Comparative yields across Pakistan show that the rust resistant varieties are equal, or superior, to current stem rust susceptible varieties grown by farmers. Deployment and use of these varieties by farmers in Balochistan will have a significant impact not only on productivity, but may also avert the consequences of possible introduction of race Ug99.
Leaf rust on high yielding winter wheats in Chile
National Institute of Agricultural Research [INIA], Chile
The physical environment and farming system in Chile are conducive to high yields from winter/alternate wheat cultivars. The national average yields for 2012-2014 were 6.5 t/ha for pasta wheat and 5.3 t/ha for bread wheat grown on 19,000 and 239,000 ha, respectively. The most efficient farmers obtain averages of 8-9 t/ha, and experimental plots at southern INIA sites are as high as 14 t/ha. The most important diseases are Septoria leaf blotch, stripe rust, powdery mildew, and BYDV. Recent increases of leaf rust on winter cultivars from near non-existence to the level of a major threat are a concern. Wheat cultivars such as Bicentenario INIA showed yield increases of 31.7% to reach 12.4 t/ha yield when sprayed twice with a mixture of strobilurin and triazol compared to 9.4 t/ha for the unsprayed control. Susceptible winter cultivars being introduced by private companies require complete chemical protection. In order to understand the virulences present in the pathogen population the Thatcher NILs were grown in 2014/15 under non-inoculated conditions in central [Chillan] and southern [Osorno] Chile. The Morocco check showed 100S, Thatcher 60S, TcLr1 40S, TcLr2b 30S, TcLr2c 40S, TcLr3a 30S, TcLr3ka 20S, TcLr3bg 30S, TcLr9 20S, TcLr10 60S, TcLr11 80S, TcLr12 60S, TcLr13 70S, TcLr14a 70S, TcLr15 50S, TcLr16 60S, TcLr17a 30S, TcLr18 20MR, TcLr19 0, TcLr20 30S, TcLr21 0, TcLr22a 0, TcLr23 70S, TcLr24 60S, TcLr25 0, TcLr26 60S, Lr27+31 80S, TcLr28 10MR, TcLr29 40MS, TcLr30 60S, TcLr32 70S, TcLr33 60S, TcLr34 70S, TcLr35 10MR–MS, Lr36 0, and TcLr37 0. The most significant differences (>40%) in response between the two locations were for TcLr2b, TcLr2c, TcLr11 and TcLr33. The Cereal Disease Laboratory (U.S.A.) tested 68 isolates from 55 samples from 2012/13 and identified 14 races, including one Triticum turgidum race (BBBQJ 26%). Significant breeding efforts are currently underway to address the leaf rust problem in Chile.
SNP discovery and genotyping of wheat-Dasypyrum villosum disomic addition lines by genotyping-by-sequencing (GBS) to facilitate identification and introgression of novel stem rust resistance genes
Department of Crop and Soil Sciences, Washington State University, USA
Most accessions of Dasypyrum villosum (2n = 2x = 14), a tertiary gene pool of wheat, were resistant in previous tests with a collection of Pgt races, including TTKSK. In order to transfer novel resistance genes with minimum linkage drag into wheat, chromosome-specific markers linked to the resistance loci would be useful. However, the currently available SNP and sequence information for D. villosum is very limited. Hence, developing SNP markers and genotyping D. villosum will aid in transferring stem rust resistance genes to wheat. We used genotyping-by-sequencing (GBS) to sequence a complete set of Chinese Spring (CS)-D. villosum addition lines (1V#3 to 7V#3) as well as CS and several D. villosum accessions to map D. villosum SNPs on each chromosome. We have also produced TTKSK-resistant CS-D. villosum amphiploids using other D. villosum accessions assuming they could carry different stem rust resistance genes.
Current status of wheat rust and its management approaches in Nepal
Plant Pathology Division, Nepal Agricultural Research Council (NARC), Nepal
Wheat is one of the three most important food crops of Nepal for which rusts (Puccinia triticina, P.striiformis and P.graminis) are major biotic stresses. Leaf rust is widespread and causes 14-20% yield losses and speculated that P.triticina over summer on self-sown wheat in hills of Nepal. Twenty two different pathotypes of P.triticina have been recorded while thirteen leaf rust resistant genes (Lr1, Lr3, Lr10, Lr13, Lr14a, Lr16, Lr17, Lr19, Lr23, Lr26, Lr27, Lr31 and Lr34) either singly or in combinations, impart resistance to wheat genotypes in Nepal. Yellow rust is also a major disease in mid and lower hills, river basin and valleys, causing 30-80 % grain yield losses. Twenty-nine pathotypes of P.striiformis have been recorded till now in Nepal while nine Yr genes (Yr2, Yr2 KSA, YrA, Yr6, Yr7, Yr9, Yr27, GA, and SU) have been postulated. Stem rust is a minor and sporadic disease in central, western, mid-western region late in the season. Nine Sr genes (Sr2, Sr5, Sr7b, Sr8, Sr8a, Sr9b, Sr11, Sr25 and Sr31) have been characterized. Vijay was the first Ug99 resistant wheat variety released for cultivation. Previous experiences show that Nepal served as a focal point of wheat rusts for further spread in the Gangetic plains of India due to presence of more than 25 species of Berberis in hills of Nepal. Efforts are underway to survey rusts infection on Berberis spp. Use of Tilt (Propiconazole), Triadimefon (Bayleton) and Indar (RH-124) was found effective to reduce leaf rust as well as foliar blight. Cultivation of resistant varieties in Nepal not only reduces rust severity in this country but also minimizes crop losses in other neighboring countries especially India. This demands the need for regional collaboration in South Asia to combat wheat rusts.
Development of wheat lines with complex resistance to rusts and Fusarium head blight
Department of Plant Sciences, University of the Free State, South Africa
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Wheat is an economically important food crop in South Africa and production is influenced by a number of diseases caused by fungal pathogens, especially leaf rust, stem rust, stripe rust and Fusarium head blight. The aim of the study is to combine durable rust and FHB resistances into a single wheat line with a high percentage of cv. Krokodil genetic background. Two sets of wheat lines respectively resistant to the three rusts or FHB were developed from different breeding programs at the University of the Free State. These lines were used as parents to combine durable rust and FHB resistance genes/QTL into a single line. Three of the best rust resistant lines were selected as female parents containing rust resistance genes/QTL Lr19, Lr34/Yr18/Sr57, Sr2, Sr26, Sr39 and QYr.sgi-2B.1. FHB resistant BC2F2 and BC2F6 lines were selected as male parents; these lines contained different combinations of Fhb1, Qfhs.ifa-5A-1 and Qfhs.ifa-5A-2. All parental lines were evaluated using molecular markers to confirm the presence of the expected genes/QTL. More than 100 crosses were made between the rust and FHB resistant parents. Since the parents were not homozygous for all markers, leaf material from six-week-old F1 seedlings was collected for marker-assisted selection and to identify the best plants with combined rust and FHB resistances. The best selected lines will be use to develop a backcross population using cv. Krokodil as the recurrent parent. Lines with different combinations of resistance genes/QTL are currently being evaluated in the field to confirm the presence of these genes/QTL.