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.
Ravi,Singh, Julio, Huerta-Espino, Mandeep, Randhawa, , , , , , , , , , , , , , , , , , , , , , , ,
Wheat leaf rust (LR) and stripe rust (YR), caused by the air-borne fungi Puccinia triticina (Pt) and Puccinia striiformis f. sp. tritici (Pst), respectively, are considered the primary biotic threats to bread wheat and durum wheat production globally. Growing resistant wheat varieties is a key method of minimizing the extent of yield losses caused by these diseases. Bread wheat lines Francolin #1, Kenya Kongoni, Kundan and Sujata, and CIMMYT-derived durum wheat lines Bairds and Dunkler display an adequate level of adult plant resistance (APR) to both leaf rust and stripe rust in Mexican field environments. Six recombinant inbred line (RIL) populations developed from crosses Avocet/Francolin #1, Avocet/Kenya Kongoni, Avocet/Kundan, Avocet/Sujata, Atred#1/Bairds and Atred#1/Dunkler were phenotyped for leaf rust response at Ciudad Obregon, Mexico, and the bread wheat populations for stripe rust response at Toluca for under artificial inoculations for multiple seasons. The RIL populations and their parents were genotyped with the 50 K diversity arrays technology (DArT) sequence system and simple sequence repeat (SSR) markers. Known pleotropic APR genes Lr46/Yr29 mapped in all of six populations, and explained 7.4-65.1% and 7.7-66.1% severity variations for LR and YR across different bread wheat populations and accounted for 12.4-60.8% of LR severity variations over two durum wheat populations. In addition, several new APR loci identified on chromosomes 1AS, 1DS, 2BS, 2BL, 3D and 7BL in bread wheat and QTL on chromosome 6BL in durum wheat. Among these loci, QTL on chromosomes 1AS, 3D and 7BL might be represent new co-located/pleotropic loci conferring APR to LR and YR. RILs combining these APR loci can be used as sources of complex APR in both bread wheat and durum wheat breeding. In addition, the closely linked single nucleotide polymorphism (SNP) markers have been converted into breeder-friendly kompetitive allele specific PCR (KASP) markers and their diagnostic verified.
John Innes Centre
Burkhard,Steuernagel, Caixia, Lan, Miroslava, Karafi?tov?, Ksenia, Krasileva, Jaroslav, Dole?el, Evans, Lagudah, Ravi, Singh, Brande, Wulff, , , , , , , , , , , , , ,
Adult Plant Resistance (APR) genes are broad-spectrum, partial-resistance genes that have the potential to contribute to sustainable control of wheat rust diseases. However, their isolation and characterization are complicated by the lack of precise molecular markers required for their identification, and therefore their use in plant breeding programs has been limited. Recent developments including the falling cost of sequencing and the increasing use of sequence capture methods to reduce genome complexity have enabled previously intractable methods such as mutational genomics to clone genes in wheat. Despite their increasing ease of use, many of these approaches require prior knowledge of the gene space and, in some cases, the gene family of the target gene to be cloned. As the APRs cloned so far do not belong to any common gene family, it is not possible to use general features of these identified APRs to conduct biased searches for novel APRs. This project aims to use an unbiased gene isolation technique called MutChromSeq, which combines chromosome flow-sorting and mutational genomics, and is independent of fine mapping, to rapidly clone the recently discovered APR gene Lr68 (Leaf Rust 68). Cloning APRs allows breeders to trace genes cheaply and quickly using gene-specific markers, enabling them to build effective and durable resistance gene pyramids. It also allows us to elucidate any common mechanism of action they have, helping researchers and breeders understand better the basis of their durable resistance. At the same time, the generation time of wheat has become one of the major limiting factors for the response time of breeders to rust epidemics. Thus, this project also aims to combine marker-assisted selection with accelerated generation advancement ('speed breeding') for rapid germplasm structuring and field performance evaluation.
University of Agriculture, faisalabad
Drought tolerance is a polygenic trait, with a complicated phenotype, often confused by plant phenology. Breeding for water stress is more complex since there are many types of abiotic stresses, such as drought, heat and salt. High yielding wheat genotypes viz., Miraj-06, 9452, 9469, 9272, 9277, CMS-127 and three testers Chakwal-50,
Kohistan-97 and Aas-11 were crossed in line ? tester mating design. Seed obtained from crosses was evaluated in field conditions for various agronomic traits under drought conditions. Recorded data were subjected to analysis of variance to determine the genetic variability. The data were analyzed statistically and combining ability
studies were tested using line ? tester analysis to find the relationship between different traits of wheat. High significant differences were observed among the lines and testers for yield related traits under stress conditions.
The female line 9452 proved to be best line on the basis of mean performance of traits under water stress. In case of testers, the male parent variety Chakwal-50 retained its performance in maximum number of traits closely followed by Aas-11. The cross combination 9272 ? Aas-11 proved best for attaining highest mean for most of
traits. In case of GCA effects line 9277 and tester Aas-11 proved best. The cross combinations 9277 ? Chakwal-50, 9452 ? Kohistan-97 exhibited highest SCA effects. The superior genotypes and crosses can be combined to develop new promising and improved varieties under water stress conditions.
John Innes Centre
Christopher,Judge, Francesca, Minter, Nik, Cunniffe, Richard, Morris, Diane, Saunders, , , , , , , , , , , , , , , , , , , ,
Wheat yellow rust is a disease caused by the fungus Puccinia striiformis f. sp tritici (PST) that is a significant threat to wheat production worldwide. Recently, a novel approach called "Field Pathogenomics" was developed that allows acquisition of genotypic data from field samples of PST-infected wheat. This has enabled us to study the re-emergence of this pathogen in the UK and understand the different races that form the current PST population. However, the dynamics of pathogen transmission and dispersal still remain unknown and understanding this is essential for designing effective surveillance. The objective of this project is to develop a spatially-explicit model for the spread of PST that can contribute to better management of the disease and be used as a warning system for wheat yellow rust infection in the UK. The first aim is to study how PST spreads at the field level and determine whether there are differences between PST races in terms of disease dynamics. To this end, a set of markers have been designed that can be used to genotype field-collected isolates and determine which race they belong to. Field trials were also undertaken across the UK using wheat varieties that are known to be susceptible to the disease, with PST-infected wheat samples collected during the 2015-2016 and 2016-2017 seasons. These samples will be genotyped to study the prevalence of different PST races and determine whether PST genotypes identified early in the season are predictive of dominant genotypes found later in the season. Understanding PST dynamics within a field is key to build an epidemiological model that can predict how this disease behaves. This would improve disease management, targeting of chemical sprays and optimize pathogen surveillance.
University of Sydney
Robert,Park, , , , , , , , , , , , , , , , , , , , , , , , , , , ,
To monitor evolution and pathogenic variability of wheat stem rust pathogen (Puccina graminis f. sp. tritici) in Australia, the Australian Cereal Rust Control program regularly conducts national annual surveys. Recently, we detected a new pathotype 34-1,2,5,7 (culture # 661) virulent on stem rust resistance genes Sr5, Sr6, Sr7b, Sr9g, Sr11, Sr15 and Sr17. Although virulent on Sr11, this pathotype produced a low infection type (IT 22+C/X) on the Sr11-differential genotype Yalta, indicating that Yalta carries an uncharacterised resistance (SrY) in addition to Sr11. To characterize SrY, we screened a RIL population Yalta/W2691 (104 lines) with two pathotypes: 21-0 (avirulent on Sr11 or AA) and the newly identified 34-1,2,5,7 (virulent on Sr11 but avirulent on SrY or BB). Yalta produced low infection types, "1C" and "22+C/X" with pathotypes 21-0 and 34-1,2,5,7, respectively, whereas W2691 was susceptible to both pathotypes. The population segregated for AA/aa (35 Res: 69 Sus) and BB/bb (36 Res: 68 Sus) loci with pathotypes 21-0 and 34-1,2,5,7, respectively. The observed segregation (AA/aa and BB/bb) however failed to fit with predicted single gene 1:1 model (P<0.05) with both pathotypes. Joint segregation analysis (AA/aa vs BB/bb) also significantly deviated (P<0.01) from 1:1:1:1 (AABB:AAbb:aaBB:aabb) genetic model. It appears that population is skewed towards susceptibility in each case either by chance or differential gametic transmission as reported previously in progenies derived from crosses involving variety Yalta. The segregation pattern (AABB and aabb) with two pathotypes was, however, highly coupled apart from 13 lines, of which, 6 lines (AAbb) were susceptible with 21-0 and resistant with 34-1,2,5,7, and 7 lines (aaBB) resistant with 21-0 and susceptible with 34-1,2,5,7, showing that the two loci are linked (?2 linkage = 76.9; P<0.001) and located very close to each other. If that is the case, it may imply that SrY is common in wheats carrying Sr11. Cultivar Charter has been used in India to differentiate pathotypes virulent for Sr11, suggesting that Charter also carries a second stem rust locus (SrC) possibly corresponding with SrY. Further studies and mapping work are underway to determine the genetic relationship between SrY, SrC and Sr11.
Wheat Program, National Agricultural Research Center (NARC) Islamabad
Sikander Khan Tanveer, Muhammad Sohail, Muhammad Shahzad Ahmed, Sayed H. Abbass, Sundas Wagar, Atiq Rattu, Muhammad Imtiaz
Wheat plays a vital role in multifaceted farming system of Pakistan. Like other many other countries, Pakistan's sustainable wheat production is also continuously threatened by a number of biotic and abiotic stresses. Among the biotic stresses, three rust diseases of wheat have been the most devastating. Stem rust was effectively controlled with adoption of the semi-dwarf spring wheats of the Green Revolution. However, the threat of the evolution of Ug99 race of stem rust in East Africa and its migration to Iran cannot be neglected. The Chance of of Ug99 migrating from Iran into Pakistan, coupled with the presence of dangerous new races of stripe and leaf rusts invites enormous efforts for development of rust resistant varieties for sustainable production of the wheat in the country. In this regard the Wheat Program, NARC, Pakistan initiated an intensive breeding program with financial and technical support of USDA and CIMMYT. Diverse sources of resistance to the three rusts particularly to the stem rust race Ug99 were introduced from CIMMYT. Through the rigorous selection procedure, four rusts resistant wheat varieties (NARC 2011, Pakistan 2013, Zincol 2016 and Borlaug 2016) have been released. These varieties are also resistant to Ug99. The varieties i.e. NARC 2011, Borlaug 2016 and Zincol 2016 are performing well in irrigated areas whereas Pakistan 2013 is suitable for rainfed conditions. The variety Zincol 2016 has high Zn content (35 ppm) in grain as compared to national standard check variety (25 ppm). These varieties are not only higher yielding but also possess good grain quality and other desirable traits. A considerable quantity of seed of the varieties is already present in the national seed system and will reduce the risk of Ug99 threat.
Institute of Agricultural Environment and Resources, Yunnan Academy of Agricultural Sciences, China
Xianming Chen, Anmin Wan, Jiasheng Chen, Mingliang Ding
Wheat stripe rust (Puccinia striiformis f. sp. tritici, Pst) is the most destructive disease of wheat worldwide. Breeding and planting resistant cultivars is the most economic, effective, as well as environmental methods to control the disease. Yunnan is a severe epidemic zone in China, which provides new incursions for other parts of China. Study on virulence of the Pst population and effectiveness of resistance genes, will provide information for breeding and rational use of resistance genes. One hundred and thirty-six136 isolates collected from 9 regions of Yunnan were tested using a set of 18 Yr NILs with genes Yr1, Yr5, Yr6, Yr7, Yr8, Yr9, Yr10, Yr15, Yr17, Yr24, Yr27, Yr32, Yr43, Yr44, YrSP, YrTr1, YrExp2, YrTyTye. Stripe rust races were named by octal code. The results showed that the Pst population in Yunnan is highly variable in races and virulence. A total of 64 races were identified and the top two most frequent races were 550273 (Virulence/Avirulence formula: 1, 6, 7, 9, 27, 43, 44, SP, Exp2, Tye / 5, 8, 10, 15, 17, 24, 32, Tr1 and 550073(Virulence/Avirulence Formula: 1, 6, 7, 9, 43, 44, SP, Exp2, Tye / 5, 8, 10, 15, 17, 24, 27, 32,Tr1), with frequency of 28.68% and 11.76%, respectively. The remaining races had frequencies less than 5.0%. No virulence were found for Yr5, Yr10, Yr15, and Yr32. The frequencies of virulence to Yr24, YrTr1, Yr8, and Yr17 ranged from 0.74% to 11.76%. The frequency of virulence to Yr27 was 52.94%; and virulence to Yr1, Yr6, Yr7, Yr9, Yr43, Yr44, YrSP, YrExp2, and YrTye ranged from 79.94% to 91.91%. The results will guide the breeding and wheat production. (This study was supported by National Natural Science Foundation of China, Grant No. 31260417 and 31560490)
KENYA AGRICULTURAL AND LIVESTOCK RESEARCH ORGANIZATION (KALRO)
Godwin Macharia, Bernice Ngina
Studies have shown that women farmers are worse off than the male counterparts in terms of adoption of improved varietal technology and hence they experience low productivity. This technology adoption gender gap affects agricultural development considering that women in Kenya play a significant role in agriculture and food production. The link between gender and adoption is likely to vary across cultures and over time. The hypothesis of significant gender differences in access to and use of productive resources and adoption of improved wheat varieties was tested. Based on bivariate analysis, significant differences in access and use of productive resources between men and women farmers were observed. Men were more likely to access credit, extension services, own and cultivate more lands compared to women. Similarly, women in female-headed households were less likely to access the productive resources compared to women in male-headed households. The factors that affect adoption of improved wheat varieties among smallholder farmers were analysed with a specific focus on women. In contrast to the conventional model of using gender of the household head, gender and plot levels analyses were conducted. The results show that the gender of the field owner had a negative effect on adoption of improved wheat varieties. This indicates that, men were more likely to adopt improved wheat varieties, compared to women farmers. Moreover, the level of education of the household head, household size, and access to credit and extension services were observed to significantly increase the likelihood of farmers adopting improved wheat varieties. In the same framework, female farmers in male-headed households who had access to credit were more likely to adopt improved wheat varieties while there was greater probability of adoption of improved wheat varieties among female farmers in female-headed households who had access to agriculture extension and belonged to a farmer organization
Instituto Nacional de Tecnologia Agropecuaria (INIA), Estaci?n La Estanzuela, Ruta 50, Km 11, Colonia, Uruguay
Vanesa,Domeniguini, N?stor, Gonz?lez, Richard, Garcia, Carolina, Saint-Pierre, Pawan, Singh, Mart?n, Quincke, Silvia, Pereyra, Silvia, Germ?n, , , , , , , , , , , , , ,
Since 2014 CGIAR-WHEAT Program has promoted the establishment of a network of field-based Precision Wheat Phenotyping Platforms (PWPP) to expand the existing collaborations between CIMMYT, ICARDA and National Agricultural Research System partners. The main goals are improving the quality of data collected and shared among institutions to enhance and accelerate the international wheat breeding, and promote synergism with the private sector and nongovernmental organizations. In 2015, the PWPP-Uruguay was established to test genotypes for multiple diseases: leaf rust, Fusarium head blight and Septoria tritici blotch. These diseases are phenotyped each year in separate field trials artificially inoculated with pathogen isolates identified as representatives of the pathogen regional population. Wheat material is sowed in plots with susceptible checks every 50 entries. Disease severity and other variables related to the disease development are measured using standard international scales at dates when the expression of plant resistance is optimal. In the first three years of the platform, more than 1500 genotypes were screened per year. These materials had diverse origins (more than eight institutions, public and private, from eight countries) and diverse types: from recent commercialized to ancient cultivars, advanced lines, International CIMMYT nurseries, mapping populations or panels. Highly resistant genotypes to multiple diseases could be selected. At the present time, we are developing and adopting advanced phenotyping methods, combining remote sensing and image analysis, and exploring their adaptation to breeding constraints. Also, extension activities as internships, training courses and student projects are being developed. Major future prospects are the enhancement of data and germplasm exchange between platform partners and the PWPP network and the involvement in collaborative phenotyping/genotyping breeding projects.