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.
Laboratoire de Biologie, Eau et Environnement, d?partement d'?cologie,university of 8 mai1945 Guelma, Algeria
Abdelkader,Benbelkacem, , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Epidemics of stripe (yellow) rust on wheat and triticale fields of Algeria in 2016. Wheat and triticale fields in 69 localities from the eastern regions of Algeria were assessed for epidemics, which started in early march to late may corresponding to booting stage up to early dough stage of the alternative type crop. The infection had incidences ranging from 30 to 100% and severities of 30 to 70%. The newly released cultivar Ksar sbahi was infected up to 10%. The old improved durum cultivars HAR3116 (SHA7/KAUZ) and HAR1407 (COOK/VEES//DOVES) were rust-free at a number of locations. In the Amhara region, the wheat cultivars were at stem elongation to flowering with disease incidences of 50-100% and severities of 30-90%. The oldest cultivar ET 13 A2 was severely infected in the north Shewa zone of Amhara region. Triticale cultivar Logaw Shibo was susceptible at elevations above 2700 m and showed trace reactions at elevations below 2500 m. The local bread wheat cultivar grown in all wheat growing areas was only slightly affected by the disease. Yellow rust was rarely recorded in the Tigray region. Severe epidemics were recorded in the highlands and even at lower elevations where it is not commonly found on wheat.
National Research Centre
Ibrahim,El-Metwally, , , , , , , , , , , , , , , , , , , , , , , , , , , ,
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.
International Maize and Wheat Improvement Center (CIMMYT), Apdo. Postal 6-641, 06600 Mexico D.F., Mexico
Ravi P.,Singh, Caixia, Lan, Bhoja R., Basnet, Sridhar, Bhavani, Julio, Huerta-Espino, Kerrie L., Forrest, Matthew J., Hayden, , , , , , , , , , , , , , , ,
Common wheat Arula displays an acceptable level of adult plant resistance (APR) to stripe rust (YR), leaf rust (LR) and stem rust (SR) in Mexico, and to SR (Ug99 races) in Kenya. A recombinant inbred line (RIL) population developed from the cross of Arula with susceptible parent Apav was phenotyped under artificially created epidemics of the three rusts in 2014, 2015 and 2016 in Mexico and for SR during the off and main seasons of 2015 in Kenya. The RIL population and parents were genotyped using an iSelect 90K SNP array and 3 gene-linked markers (Sr2/Yr30-gwm533; Lr34/Yr18/Sr57-csLV34; Lr68-csGS), and a genetic map of 2,634 markers was constructed to locate the resistance loci. Two consistent QTL contributed by Arula were detected on chromosomes 3BS and 7DS, which corresponded to the previously known APR genes Sr2/Yr30 and Lr34/Yr18/Sr57, respectively. Sr2/Yr30 explained 1.1-14.7% and 41.0-61.5% of the phenotypic variation for YR and SR, respectively; whereas Lr34/Yr18/Sr57 accounted for 22.5-78.0%, 40.0-84.3% and 13.8-24.8% of the phenotypic variation for YR, LR and SR, respectively. Arula was also found to carry the positive allele for marker csGS closely linked to gene Lr68 on chromosome 7BL, although this gene was not detected using composite interval mapping. Our results show that RILs possessing both Sr2/Yr30 and Lr34/Yr18/Sr57 had significantly enhanced APR to all three rusts in field trials conducted in Mexico and Kenya. Strategic utilization of these two pleiotropic, multi-pathogen resistance genes with other minor genes is recommended to develop durable rust resistant wheat cultivars.
Research Institute of Crop Husbandry, Azerbaijan
ATIF,ZAMANOV, Konul, Aslanova, , , , , , , , , , , , , , , , , , , , , , , , , ,
Rust diseases are considered the main stress factors that limit wheat productivity in the Azerbaijan. The studies on the impact of rust diseases on physiological processes at reproductive vegetation period is of very importance with view of evaluating size of yield and quality of the studied genotypes. For this purpose the studies focused on bread wheat genotypes (Triticum aestivum L.), which differ sharply by architectonics, biological peculiarities and resistance to rust diseases. Comparative evaluation of the studied genotypes by physiological and quality parameters has been undertaken in two options: over plants infected with diseases in natural background, and over healthy plants (fungicide sprayed plants). Area of photosynthesis apparatus of leaf story (18,3-50,2 sm2) of the studied wheat genotypes changes in wide interval. Infestation level of leaves with yellow rust (Puccinia striiformis West.) in wheat genotypes grown in natural infection background fluctuates between 5MS-40S in ontogenesis, but between 10MS-90S with brown rust (Puccinia recondita Desm.).
High level of infection with rust diseases leads to reduced size of leaf assimilation area and defoliation. Reduction of these dimensions makes up 10-90% in lower story leaves of genotypes infected with rust diseases, but 20-30% in upper story leaves. Genotypes with large and bending leaves subject to this disease more frequently. Value of photosynthesis intensity in ontogenesis at upper story leaves of the genotypes infected with rust diseases at natural background fluctuates between 6-18 ?mol CO2 .m-2.s-1 depending on level of infection, but in healthy plants between 16-29 ?molCO2 .m-2.s-1. Negative impact of these diseases on normal course of plant physiological process ultimately causes is reflected in yield and quality parameters.
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.
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.
Wheat Research Institute, Faisalabad, Pakistan
Ghulam Mahboob,Subhani, Javed, Ahmad, Abid, Mahmood, , , , , , , , , , , , , , , , , , , , , , , ,
Global warming affects the environmental parameters of agro-based countries like temperature increase, melting of glaciers, floods, erratic rains, low temperature, frost and high temperature. As a result agriculture is becoming more vulnerable to global environmental shifts. In case of wheat, erratic or low rains badly affect the wheat crop of rainfed areas of the country along with high temperature at seedling or juvenile stage. Similarly, frost affects the early sown wheat crop in irrigated areas of Punjab. Lesser availability of irrigation water from water reservoirs also reduces the wheat crop productivity. Sudden increase in temperature (>30?C) during the month of March adversely affect the grain filling. High temperature during grain filling stage interferes with the photosynthetic activities of the plant due to enhanced maturity, grain become shriveled and results in low grain yield. The threat of these environmental changes can only be overcome through breeding with specific objectives which is cost effective once obtained.
Hence development of wheat varieties for frost, drought and heat tolerance is the only feasible solution to combat these stresses which is being used at Wheat Program of Ayub Agricultural Research Institute, Faisalabad, Pakistan. New emphasis is also being given to develop frost resistant wheat varieties due to changing scenario of last few years. The institute is actively involved for the development of heat, drought and frost tolerant wheat varieties. During working for tolerance against any of these stresses plant types to be breed are physiologically and morphologically modeled in such a way that they should be capable of tolerating respective stress. In addition to breeding work an extensive research is also being done at Wheat Research Institute, AARI., Faisalabad to investigate best agronomic strategies to make wheat crop best adapted to environmental stress conditions.
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.