Northwest A&F University
Yanping,Fu, kang, Wang, Yingbin, Hao, Zhensheng, Kang, , , , , , , , , , , , , , , , , , , , , ,
Wheat adult plant resistance (APR) to stripe rust, a non-race-specific and durable resistance, is ideal for breeding. However, the knowledge concerning APR mechanism is largely limited. In order to further investigate the molecular basics of APR to provide guidance for wheat breeding, we conducted the transcriptome sequencing of wheat XZ9104 infected by Puccinia striiformis f. sp. tritici (Pst) at seeding and adult stages, respectively. Comparative analysis revealed that many WRKY transcription factors (TFs) may participate in the APR to stripe rust, of which, TaWRKY79 transcript levels were sharply elevated at the early infection stage in seedling plants. To dissect the relationship between TaWRKY79 and APR, we further studied the function of TaWRKY79. Subcellular localization showed that TaWRKY79 is located in the nuclear, and TaWRKY79 protein contains a separated region for mediating transcriptional activation at the C-terminus (246-328 aa) by yeast one-hybrid analysis. When TaWRKY79 was silenced by virus-induced gene silencing (VIGS) in seedling plants, the Pst growth was attenuated, with shortened hyphae, reduced hyphal branches and colony size. Meanwhile, the expression of TaWRKY79 was highly suppressed by salicylic acid (SA) but induced by jasmonic acid (JA) in seedling of wheat, and the transcription levels of LOX2 and PDF2.2 were significantly reduced, but the expression of PR1.1 was enhanced in TaWRKY79 knocking-down seedlings of wheat. Hence, these findings suggested that TaWRKY79, as a SA/JA cross talk, might play a negative role in resistance defence response to Pst infection at seeding stage by simultaneously activating the JA-dependent pathway and suppressing the SA-dependent pathway.
Abd El Badia
Wheat Disease Research Department
Mohamed Abdalla, Sobhy Negm, Adel Hagras
This work was carried out to study the response of five bread and two durum wheat cultivars to stem rust and its effect on grain yield under field conditions at Sids and Beni Sweif stations during the three growing seasons 2011/2012, 2012/2013 and 2013/2014. The loss in grain yield and kernel weight of the different wheat genotypes was variable according to the varietal response. Grain yield and kernel weight of the protected plots (protected by the effective fungicide Sumi-eight 5EC(CE)-1-(2,4-dichlorophenyl)1-4,4-dimethyl1-2-(1,2,4-triazol-y1)Pent -1-en -3-0L) at the rate of 70cm /200litter water per Fadden ) of all wheat genotypes were higher than the infected ones. Significant differences were found between infected and protected wheat genotypes.. Disease severity was recorded weekly to estimate area under disease progress curve (AUDPC). The AUDPC ranged from 85.33 to 405.00 (Sids 1 and Sohag 3) during 2011/2012, from 181.66 to 805.00 (Shandwel 1 and Sohag 3) during 2012/2013, and from 142.33 to 585.00 (Shandwel 1 and Sohag 3) during 2013/2014. Losses in kernel weight ranged from 3.39% to 31.03% (Sids 1 and Misr 1) during 2011/2012, from 9.79% to 44.18% (Sids 1 and Sohag 3) during 2012/2013,and from 5.67% to 26.86% (Sids 1 and Sohag 3) during 2013/2014. Yield losses ranged from 5.70% to 37.52% (Shandwel 1 and Misr 1) during 2011/2012, from 7.75% to 45.78% (Shandwel 1 and Misr 1) during 2012/2013, and from 7.14% to 30.59% (Sids 1 and Sohag 3) during 2013/2014. Yield losses correlated strongly with AUDPC. The results of this study indicate that bread wheat cultivars are (Giza 168,Sakha 93, Sids 1, Misr 1, Misr 2 and Shandwel 1) and Durum wheat are ( Beni Sweif 5 and Sohag 3) more tolerant than durum wheat cultivars. The Egyptian bread wheat cultivars Sids 1 and Shandawel 1 are more tolerant than the other bread wheat cultivars.
Agriculture and Agri-Food Canada, Lethbridge, Alberta
Gurcharn Brar, Randy Kutcher, Raman Dhariwal
Stripe rust of wheat, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases of wheat in western Canada. Although stripe rust was an issue in southern Alberta for many years, it became important in other parts of the country after a dramatic population shift in 2000, resulting from an invasive race. Sporadic epidemics of the disease are common and cause considerable loss, due to which, an intermediate level of resistance to stripe rust was required for new varietal registrations beginning 2017. Virulence surveys are of key importance in germplasm and cultivar development as they provide breeders and pathologists the information needed to better understand host-pathogen interactions and the effectiveness of Yr genes. Virulence characterization revealed a wide range of virulence phenotypes exhibited by 33 Pst races in western Canada, although only 2-3 races were predominant. The expression of Yr genes may differ between controlled conditions and natural field conditions as previously reported. Thus, stripe rust differentials and wheat cultivars grown in western Canada are also screened at multiple locations in every year. At present, all stage resistance genes Yr1, Yr4, Yr5, Yr15, Yr76, and YrSP are effective against the predominant Pst races, whereas at the adult stage under field conditions, Yr2, Yr17, Yr28, or those carried by Yamhill are also effective. Seedling resistance genes Yr7, Yr10, Yr17, or Yr27 were the most common in Canadian wheat cultivars. Of these, only Yr17 is effective under field conditions. Adult plant resistance genes Yr18 and Yr29 are carried by many cultivars, but are not effective under high disease pressure. The effectiveness of each resistance gene may vary between the eastern and western prairies of western Canada due to differences in virulence. Regular virulence surveys using contemporary and regional cultivars facilitate the development of rust resistant cultivars.
ICAR-IARI, New Delhi
Sudheer Kumar, Subhash Chandar Bhardwaj, Om Prakash Gangwar, Vaibhav Kumar Singh, Mukesh Kumar Pandey, Jaspal Kaur, Ashwani Kumar Basandrai, Deepshikha, Pradeep Singh Shekhawat, R.K. Devlash, V.K. Rathee
In India, wheat crop is a major contributor to the agricultural economy of India, occupying 30.7 mha area with 98.38 mt production. Stripe or yellow rust is a constraint to wheat production on about 12.0 m ha in the Northern Hills and North Western region of India. Varieties resistant at the time of release become susceptible usually within a few years due to new pathogen races. The present study conducted in 2015-16 was undertaken to identify stripe rust resistant genotypes among a set of 146 advanced breeding lines and popular cultivars. All genotypes were planted in two replications in northern India at ten locations viz., Karnal, Hisar (Haryana), Ludhiana, Gurdaspur (Punjab), Malan, Bajoura, Dhaulakuan (Himachal Pradesh), Pantnagar (Uttarakhand), Durgapura (Rajasthan), Jammu (J & K) and Delhi. After every 20 genotypes, infector (susceptible cultivar to both pathotypes) was planted. All genotypes were inoculated with mixture of prevalent Pst races 78S84 (Yr 27 virulence) and 46S119 (Yr 9 virulence) at Karnal. Out of 58 released cultivars grown in different zones of the country, fifteen lines (HS 507, DBW 90, HD 3086, WH 1080, WH 1124, WH 1142, HD 4728, HI 8498, HI 8737, MPO 1215 (D), NIDW 295 (d), UAS 428 (D), UAS 446 (D), DBW 71, KRL 210) showed stripe rust ACI < 10.00 (average coefficient of infection). But among advance 88 wheat lines, there was good level of resistance in 50 lines (ACI <10.00). Lines having AUDPC values <20% of those of the susceptible checks (maximum AUDPC value 2500 on susceptible check) were considered to be slow rusters. In present study, some of the wheat varieties (DBW 93, HS 490, PBW 723, PBW 644, VL 829, VL 892, WH 1105, WR 544 ) grown at present in northern India were identified as slow ruster lines. The information generated can be utilized in improving the stripe rust resistance of popular cultivars.
Nepal Agricultural Research Council (NARC)
Suraj Baidya, Dhruba Bahadur Thapa, Roshan Basnet, Sunita Adhikari, Prem Bahadur Magar, Ajaya Karkee, Nabin Dangal, Basistha Acharya, Ram Bahadur Khadka, Junga Bahadur Prasad, Purusottam Jha, Laxman Aryal, Prakash Pantha
Rusts are one of major threats to reduce wheat production and productivity in Nepal. Rust fungi are obligate parasite survival during off-season either on voluntary wheat plants or other grass or timber plant species is not yet confirmed in Nepal. High-inputs, suitable hosts and existence of warm humid and cool high lands in different parts of country promote carryover of inoculums of rust fungi. Nepal could be potential sources of yellow rust and leaf rust epidemic for itself and for Indian sub-continent. Surveillance is one of important steps to know status of wheat diseases especially rusts occurrence in country. The SAARC rust tool box is systematic and regular monitoring activity of wheat and barley diseases conducted at various locations in Nepal. Altogether, 183 and 180 locations were surveyed in different parts of Nepal were put in global rust tool box server and validated in fiscal years 2014/15 and 2015/16. Wheat rusts disease scenario has been observed differently, it could be due to climate change and different virulent spectrum of races/pathotypes of rusts fungi and deployment of different wheat varieties. Yellow rust was widely occurred throughout mid hills in Nepal. Higher severity of yellow rust was observed in Kathmandu valley (80S -100S). Leaf rust was moderate to high (10MS-100S) in plain and hills. There was higher score of leaf rust observed in plain as well as in mid hills on susceptible wheat cultivar. Regular monitoring and surveillance at different locations in Nepal has been found helpful in digging out actual problems of wheat crop. Monitoring races of all three rusts occurring in Nepal is necessary for successful planning to manage rusts by deploying effective genes. Rust tool box is important to keep vigilance of new emerging rust races in country. This in turn could increase production and productivity of wheat in Nepal.
Hawassa Agriculture Research Centre
Agdew Bekele, Waga Mazengia, Shimekt Maru
Shortage of seed of rust resistant varieties is a challenge of small holder farmers in wheat production. To successfully address this issue, one of the essential elements in wheat production system is farmer's access to quality seed of improved varieties. This paper presents the experience of on-farm basic and pre-basic seed production of newly released rust resistant wheat varieties. For the first time in the country, On-Farm basic and pre-basic seed production of wheat varieties was carried out in two districts/woredas (Silti and Soddo) of two specific locations (Loke faka and Wacho) where the Edget Farmers' Seed Multiplier and Marketing Union was licensed to produce some crop varieties (cereals and pulse), beginning in the 2011/2012 cropping season. Model farmers from primary cooperatives were selected based on the past experience they had with the union in producing certified seed. Selected farmers and relevant experts were trained on how earh seed of wheat is produced. Accordingly seed multiplication of four wheat varieties was conducted with frequent monitoring and evaluation at the course of multiplication.
As a result sufficient and quality basic seed of newly released wheat varieties was produced on-farm in both Loke and Wacho locations for own utilization and seed market. The result of the experiment revealed that it was possible to multiply quality wheat seed provided that partnership (with GOs and/or NGOs) is well-built and cooperative farmers do farm management practices as per the recommendations. On-farm seed production can be sustainable if the strong partnership exists among stakeholders, and wheat seed growers are given premium prices for their seed which is supported by the legal frame work that encourages the seed production of early generations. More importantly, the result of this experiment has a useful implication on government policies and strategies and government institutions' practice on farm early seed generation production and marketing.
Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
Punam Singh Yadav, Ramesh Chand, Vinod Kumar Mishra, Uttam Kumar, Arun Kumar Joshi
The Sr2 gene has been used extensively in bread wheat improvement for durable stem rust resistance. Interestingly, the resistance of Sr2, associated with the pleotrophic gene Pbc expressed as pseudo-black chaff (PBC), is tightly linked with Yr30/Lr27/Pm genes conferring multiple disease resistance. The linkage map of chromosome 3BS revealed that Sr2 is 0.43cM away from lesion mimic (lm) locus. The RIL population (Yangmai#6 ? Sonalika) of 88 lines including parents where Sonalika carries Sr2 and lm while Yangmai#6 is deficient to both was evaluated for three years (2013-2016). The objective was to determine if this fragment is inherited as one unit and provides resistance to multiple diseases. Twenty four SSR markers distributed between 0.00 to 7.09cM on 3BS covering both Sr2 (5.57cM) and lm locus (6.0cM) were studied in the RIL population. Phenotyping was done for Sr2 associated PBC and lesion mimic along with disease severity for leaf rust, and spot blotch. Positive and significant correlations were observed between leaf stem rust resistance with Sr2 carrying PBC and lm. However, lines with lm either alone or with Sr2 (showing PBC) exhibited spot blotch susceptibility. The reverse situation does not hold not true where genotypes carrying Sr2 alone showed no correlation with spot blotch resistance. This indicates that the Sr2 complex is inherited as a single unit. Use of 24 SSR also suggest that Sr2 and lm loci are tightly linked and inherited together. The co-inheritance of Sr2 and lm ensures the stability and durability of rust resistance. However, the discouraging observation of spot blotch susceptibility due to lm gene suggests a limitation in achieving multiple disease resistance in environments where spot blotch is important. We identified two transgressive segregates in the population showing least expression of lm despite the presence of Sr2 and lm together.
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.
Kenya Agricultural and Livestock Research Organization
Hanningtone,Wanga, Phelister, Kinyanjui, Sridhar, Bhavani, Thomas, Fetch, , , , , , , , , , , , , , , , , , , , , ,
In 2016 rust surveys were carried out in all the four key wheat growing regions: South Rift (June, July), Mount Kenya (July), North Rift (September) and Central Rift (part of August and September). A total of 304 farms were sampled. Stem rust was detected in 235 (78.3%), yellow rust in twenty-eight (9.3%) and leaf rust in fourteen (4.7%) of the farms. Stem and yellow rust were detected in all the wheat growing regions while leaf rust was detected in South, North and Central Rift. Stem rust infection ranged from TR to 90S with maximum infection in Central Rift (88.3%), Mt. Kenya region (80.3%); South Rift (76.5%) and North Rift (72.4%). Yellow rust infection ranged TR to 60S with maximum infection in Central Rift (16.7%); North Rift(13.3 %) and minimum infection in South Rift( 4.9%),) and Mt. Kenya region ( 1.7%). Leaf rust infection ranged from trace to 50S with maximum infection in North Rift (10.2%) minimum infection in Central Rift (3.3 %) and South Rift (1.2%). Fifty percent of the eight previously released wheat varieties are now susceptible to the Ug99 race. Race analysis results from AAFC Canada suggested the presence of TTKSK which was dominating in North Rift and TTKSK, TTKST and TTTTF were dominant in the screening nursery at Njoro. Yellow rust in the region has increased in the current year owing to the incursion of a probable new race AF2012 which has resulted in increased disease severity on varieties and materials tested in the International nurseries at KALRO, Njoro.
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.