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.
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.
Ethiopian institute of agricultural research
Dr. Netsanet B. Heyi, Dr. Getaneh W. Wolderufael, Tsegab T.
Stem rust caused by Puccinia graminis f. sp. tritici (Pgt) is a major production constraint in most wheat growing areas of Ethiopia. The stem rust pathogen is capable of rapidly developing new virulence to resistance genes. The highlands of Ethiopia are considered a hot spot for Pgt diversity. The present study was conducted to investigate the virulence diversity and spatial distribution of races of Pgt in the major wheat growing areas of Ethiopia. The physiologic races of Pgt were determined on seedlings of the standard wheat stem rust differentials following the international system of nomenclature. Stem rust race analyses were carried out both at Ambo Plant Protection Center and the Cereal Disease Laboratory in Minnesota. 426 stem rust samples were collected from major wheat growing of the country in the 2016 cropping season and 185 viable samples were analyzed. Stem rust races TKTTF, TTKSK, TTTTF, JRCQC and RRTTF were identified. Among the identified races, TKTTTF was dominant at a frequency of 78.7% followed by TTKSK (10.6%). Race TTTTF was found for the first time in Ethiopia in 2016. Only one resistance gene in the differential set, Sr24, was effective against all isolates. Stem rust resistance gene Sr31 was found to confer resistance to most of the races prevalent in Ethiopia with the exception of Ug99. Sr24 could be used in combination with other resistance genes in breeding for resistance to stem rust in Ethiopia.
North Dakota State University
The rapid adoption of new varieties of wheat with disease resistance is critical to mitigating losses due to new diseases or disease races, even when only part of an integrated disease management program may include fungicides. There are numerous sources of information that can be used by farmers in North Dakota when selecting varieties with specific disease resistance as well as other traits. Formal surveys were conducted to determine the role of extension activities on the adoption of Fusarium Head Blight (FHB) control practices especially on the use of new varieties with FHB resistance. This disease became a regular and devastating problem of small grains in eastern North Dakotas in the 1990s. In a survey specific to North Dakota conducted in 2010, most respondents indicated that information from the extension service was their main source of information for FHB control with varietal selection their primary means of control. Extension publications, accessed through the internet or as hard copy obtained from an extension office or at an extension meeting were the most important sources; fewer respondents obtain their information from extension meetings and field days. A survey conducted in 2014 found that private sources (consultants and input suppliers) are becoming more important sources of information for FHB control and varietal selection, perhaps because the disease has become better understood and most new varieties have some level of FHB resistance. In durum wheat, where there are few varieties available from the private sector, extension publications were found to be the main source of information used for selecting new varieties. Data from these surveys show the importance of a strong and active extension program in ensuring that new varieties with resistance to new diseases/disease races are readily adopted.
Dryland Agricultural Research Institute, Sararood branch, AREEO, Kermanshah, Iran
Ehsan,Lorestani, Reza, Haghparast, Mohammad Reza, Jalal Kamali, Ahmed, Amri, , , , , , , , , , , , , , , , , , , , , ,
Yellow rust (Puccinia striiformis Westendorf f. sp. tritici) is an important disease on wheat worldwide and especially in the highlands of West and Central Asia. Wheat landraces are composed of complex, variable, genetically dynamic and diverse populations, in equilibrium with both biotic and abiotic stresses prevailing in their environment. A germplasm collection consisting of 380 durum wheat accessions conserved at National Plant Gene Bank (Seed and Plant Improvement Institute, Iran) with worldwide origins, along with four check varieties were screened for resistance to yellow rust, and were also evaluated for several drought adaptative traits under rainfed conditions during 2009-10 cropping season at Sararood agricultural research station, Kermanshah, Iran. The study was conducted to quantify the phenotypic diversity and exploring durum accessions for yellow rust resistance, and to characterize the agronomic profile of different subsets of accessions for reaction to local yellow rust races. High natural infection, caused by the predominant virulent races of 6E8A+ and Yr27+, was experienced as shown by the 100 S reaction of the check bread wheat ?Sardari? and several highly susceptible accessions. The tested accessions exhibited significant variation in yellow rust severity, ranging from highly resistant to highly susceptible. Approximately 12.1% of accessions were found to be resistant to yellow rust, 9.5% were moderately resistant, 10.5% were moderately susceptible and 67.9% were susceptible. The germplasm showed a relatively modest response to yellow rust as expressed by a decrease in 1000-kernel weight (TKW) and a lower yield of the susceptible vs. resistant subsets by 11.4% and 19.9%, respectively. A comparison of foreign vs. Iranian resistant accessions, revealed higher yield productivity, higher TKW, and shorter plant height for the foreign accessions. Durum germplasm may constitute valuable genetic material for breeding new durum varieties characterized by high yield productivity under rainfed conditions and with adequate resistance to yellow rust.
Wheat Research Institute, Ayub Agricultural Research Institute,Faisalabad,Pakistan
Javed Ahmad, Ghulam Mehboob Subhani, Makhdoom Hussain
Crops vary greatly in their tolerance to heat stress. Among the major staples wheat is considered the most sensitive. Wheat production is severely threatened in many countries by heat stress especially during reproductive and grain-filling stages. For recent decades due to change in global climate, the qualitative and quantitative yield of wheat is affected. To meet the demand of food requirements of ever increasing population there is a need to develop varieties which can tolerate heat stress for which screening of germplasm is pre requisite. In the present study, 30 genotypes were used to check their response to heat stress using randomized complete block design following two different sowing dates. Analysis of variance and multivariate analysis were used for finding important traits and best genotypes in relation to heat stress. High broad sense heritability coupled with high genetic advance was measured for gluten and zeleny indicating the presence of additive gene effect for these traits. Principal component analysis showed that under heat stress conditions genotype 11, 14, 15, 20 and 30 performed well. These genotypes were also found resistant to yellow and brown rust and can be used in further breeding programs for development of heat tolerant, rust resistant genotypes.
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.
Plant Pathology Research Institute
Atef Shahin, Mohamed Abu Zaid
Resistance genes Sr2, Sr22, Sr24, Sr25 and Sr26 confer adult plant resistance to Pgt race TTKSK (=Ug99). Ten Egyptian wheat varieties and four bread wheat entries from CIMMYT were screened with five DNA markers to determine the presence of these genes, and were evaluated for stem rust response at Sakha and Sids during the successive growing seasons of 2015/16 and 2016/17. Varieties Giza 171, Sakha 94, Gemmeiza 11, and CIMMYT lines 6043, 6091, 6107 and 6197 were resistant with severities ranging from TrR to 5MR/MS. Sr2 was present in all entries; Sr24 was present in one local Egyptian cultivar (Misr2); Sr25 was present in Misr 1, Misr 2, Gemmeiza 9, Gemmeiza 11, and lines 6091 and 6197; and Sr26 was present in line 6197.
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.
USDA-ARS, Pullman, WA, USA
Lu Liu, Meinan Wang, Junyan Feng, Deven See, Shiaoman Chao
Stripe rust, caused by Puccinia striiformis f. sp. tritici, is the most destructive disease of wheat in the US Pacific Northwest. Durable high-temperature adult-plant (HTAP) resistance to stripe rust has been emphasized for breeding wheat cultivars and the resistance level has been gradually increased since the early 1960s. Wheat cultivar Madsen has been widely grown, intensively used in breeding programs, and has exhibited durable and high level resistance to stripe rust since its release in 1988. To map its resistance genes and determine the genetic basis of durable and high-level of resistance, Madsen was crossed with susceptible cultivar Avocet S, and 156 recombinant inbred lines (RILs) were developed. The RILs and parents were tested with races PSTv-37 and PSTv-40 in seedling stage at low temperatures in the greenhouse and in adult-plant stage in the fields of Pullman and Mount Vernon, WA in 2015 and 2016 under natural infection of the pathogen. The RILs were genotyped with single-nucleotide polymorphism (SNP) markers derived from genotyping by sequencing and the 90K Illumina iSelect wheat SNP chip. A linkage map was constructed with 1,348 SNP loci. QTL analysis identified three genes for all-stage resistance on chromosomes 1AS (QYrMad.wgp-1AS), 1BS (QYrMad.wgp-1BS), and 2AS (QYrMad.wgp-2AS); and two QTL for HTAP resistance on 3B (QYrMad.wgp-3B) and 6B (QYrMad.wgp-6B). QYrMad.wgp-2AS was the most significant QTL, explaining 16.03-71.23% phenotypic variation depending upon the race or environment, followed by QYrMad.wgp-6B that was consistently detected in all field experiments and explained 6.7-35.9% of the phenotypic variations. Based on the chromosomal locations and the results from other studies, QYrMad.wgp-2AS contains Yr17 and a HTAP resistance QTL, and QYrMad.wgp-1AS is a new QTL. The interactions among these QTL were mostly additive. The combination of the five QTL for different types of resistance provides the durable and high level resistance to stripe rust.