Ravi P.,Singh, Julio, Huerta-Espino, , , , , , , , , , , , , , , , , , , , , , , , , ,
Aphids are major pests of wheat, able to cause up to 40% yield reduction solely due to direct feeding and up to 60% when feeding is combined with the transmission of viral diseases. Wheat resistance to aphids has proven to be effective in protecting yields and also in reducing the transmission rate of viral diseases. Moreover, aphid resistance is fundamental to reduce the negative impacts that the indiscriminate use of insecticides have on the environment and human health. In this study we report the results derived from the evaluation of 326 synthetic hexaploid wheat (SHW) derived lines against the greenbug (Schizaphis graminum [Rondai]). Primary SHWs were crossed with CIMMYT elite lines and further selected in the breeding pipeline. Therefore, such lines have acceptable agronomic characteristics for its further use in breeding programs. The 326 SHW derived lines were evaluated at seedling stage, in five augmented incomplete blocks, arranged in split-plots, with two treatments (infested vs. non-infested) and with resistant and susceptible checks replicated 16 times. The measured variables were chlorophyll content with a SPAD meter and a visual damage score in a scale 0-100 was also taken. Measurements were recorded when the susceptible check was dead due to aphid feeding. The evaluations were repeated two times for confirmation. Our results indicate the presence of genetic variation for S. graminum resistance. We identified about 4 % of the lines to carry high levels of resistance against this aphid. These lines are currently used in CIMMYT's bread wheat breeding program to incorporate the resistance in elite germplasm.
Mohammad,Kassem, Ghinwa, Lababedi, Naim, Al-Husien, , , , , , , , , , , , , , , , , , , , , , , ,
Leaf rust is the most common rust in wheat production areas of Syria and causes significant annual yield losses. Using genotypes with durable resistance is the most economical way of controlling the disease. One of the best-known leaf rust resistance genes is Lr46 that confers a slow rusting type of adult plant resistance. The main objective of this study was to identify Lr46 in durum wheat genotypes using morphological and molecular markers. Thirty-two durum wheat genotypes were evaluated for response to leaf rust at the seedling and adult plant stages. Twelve genotypes (37.5%) were resistant (R), 10 (31.25%) were moderately resistant (MR), seven (21.87%) were moderately susceptible (MS), and three (9.37%) were susceptible (S). Molecular marker analyses using SSR marker wmc44 showed that 16 genotypes (50%) carried Lr46/Yr29. The genotypes possessing the marker linked to Lr46/Yr29 could be used for selection of Lr46/Yr29 in breeding for slow rusting resistance in durum.
The University of Agriculture, Peshawar, Pakistan
Muhammad,Khan, Muhammad, Imtiaz, Zahoor, Swati, Annemarie, Justesen, Sajid, Ali, , , , , , , , , , , , , , , , , , , ,
Yellow rust caused by Puccinia striiformis is an important disease in Pakistan. The population structure of P. striiformis in the North Eastern Himalayan region of Pakistan have been shown to be genotypically diverse with potential role of sexual recombination (Ali et al., 2014b), while lesser diversity in the Southern districts of Khyber Pakhtunkhwa (KP)(Khan et al., 2015). This study was designed for the first time to assess disease status and analyze population structure of P. striiformis across three distant parts of Northwestern Pakistan i.e., Bajaur in North Western Agency and Swat and Buner in Malakand Agency, and was compared with other Pakistani populations. Depending on the intensity of infections caused by the pathogen in the tested varieties and breeding lines, the severity of the disease ranged from 5% to 100% during 2015. Yellow rust severity was the maximum on Morocco (100%), Gomal (100%) and KPWYT-18 (80%) and moderate on Ghanimat-e-IBGE (10%) and PS-2008, PS-2013, Tatara and Millat with 20% severity. A total of 81 single lesion samples collected on infected varieties were genotyped with 18 microsatellite markers. From these, 63 distinct multilocus genotypes (MLGs) were detected; 15 single lesion samples collected from Buner produced 15 distinct MLGs signifying very high diversity. A high genotypic diversity with clear signature of recombination was detected across all the three locations. Buner (100%) had the maximum diversity followed by Swat (97%) and Bajaur (91%). The observed diversity was almost equal to other Northeastern Himalayan populations of Pakistan, while it was high when compared to some southern populations of KP (genotypic diversity of 0.895) and other worldwide clonal populations (Ali et al., 2014a). The high diversity and recombinant population structure suggested potential role of sexual reproduction in these areas, which needs to be further explored to establish the origin of diverse virulence pattern in Pakistan.
Sathguru Management Consultants
Venugopal,Chintada, Vijay, Paranjape, Mansi, Naithani, Aishwarya, Vardhan, , , , , , , , , , , , , , , , , , , , , ,
Nepal is an important wheat producer country in the South Asian region; with wheat being the third most important crop in the country after paddy (rice) and maize. Additionally, high-quality, disease free, processed seed is vital to establishing food security in South Asia. The Agriculture and Forestry University or AFU, located in the fertile Chitwan region of Nepal, is the only agriculture university catering to the needs of the Terai region and has the capability to provide innovative wheat seed solutions for small wheat-growing farmers. In the Delivering Genetic Gain Project or DGGW, the AFU has an active involvement in seed production, processing, and distribution. These activities play a major role in human capacity building in the country involving women empowerment, whole family participation in varietal selection and entrepreneurship for sustainable livelihood and overall development. Currently, under the DGGW?s Innovative Seed System in Nepal, AFU produces and aggregates seeds from farmers in the area and process it through a new seed processing unit, which is a cost-efficient version of machines commonly seen in larger agricultural facilities. At full capacity, the unit can operate up to 18 hours a day and process one ton of seed per hour. The unit it is also capable of processing rice and maize during other cropping seasons. By March 2017, more than 200 farmers applied to be part of the inaugural cohort of farmers trained in producing disease free wheat seed. The inaugural wheat season for the Seed Systems for Nepal Initiative has concluded successfully, with a total of 14 metric tons of disease-free wheat seed processed. The DGGW Seeds Systems for Nepal Initiative envisions to increase the number of empowered farmers next season, which commences on November, 2017.
University of Seville
Solis,Ignacio, , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Leaf rust is an important worldwide disease on wheat caused by the fungus Puccinia triticina. Great infections on durum wheat occurred in Southern Spain in the 2000s but diminished in recent years due to deployment of resistant varieties and application of fungicides by farmers. A leaf rust survey was carried out from the 2009-15 period to monitor the virulence spectrum of the prevailing pathotypes. A total of 84 leaf rust isolates were collected on durum wheat fields. From those, single culture were obtained and used to inoculate a set of 27 differential isolines of the susceptible variety Thatcher. In addition 8 durum varieties with known Lr genes were also included.
The main highlight is that the resistance conferred by the popular Lr14a gene was broke up in 2013, but since then virulence to this gene is not widespread. In total, 23% of the isolates were virulent to the lines containing Lr14a. Lr1, Lr3, Lr3bg, Lr16, Lr24, Lr26, and Lr28 are very effective. Lines carrying Lr2c, Lr10, Lr14b, Lr20, Lr23, and LrB displayed susceptibility to most isolates. The durum varieties Jupare (Lr27+Lr31), Guayacan (Lr61), Storlom (Lr3+) and Camayo (LrCam) are also resistant against all isolates tested. Diversification of Lr genes is needed in the coming varieties to delay the appearance of new virulent races.
Ahi Evran University, Agriculture Faculty, Plant Protection Department K?rsehir/Turkey
Nil?fer,Akci, Marta da Silva, Lopes, , , , , , , , , , , , , , , , , , , , , , , , , ,
Stem rust (Puccinia graminis f. sp. tritici) is a fungal disease that can significantly reduce wheat yields and quality. The goal of this study was to screen 281 winter bread wheat landraces genotypes for their reaction to stem rust disease in seedling and adult plant stage.
For seedling stage, the experiment was carried out under greenhouse conditions in Field Crops Central Research Institute in Ankara, Turkey during 2017 growing season. The genotypes were grown at 20?4?C under greenhouse condition and inoculated (avirulent on Sr24, 26, 27, and 31 resistance genes) with urediniospores in mineral oil suspension at Zadoks growth stage 11 or 12. After inoculation, the genotypes were incubated at 20?1?C with 100% humidity during 24 hours then at 18-25?C. Scoring took place after 14 days using a 0-4 scale. Infection types on the susceptible checks (cv. Gun-91 and Thatcher) were 3+ scores. For adult plant reactions, the genotypes were screened under natural epidemic conditions for Pgt (virulent on Sr5, 6, 7b, 8a, 8b, 9b, 9g, 10, 30, Tmp and Mcn resistance genes) in Seydiler-Kastamonu, Turkey. The materials were sown in a one-meter row with three replications. Stem rust development on each entry was scored using the modified Cobb scale (Little Club had reached 80-100S) in August 2017. Coefficients of infections were calculated and values below 20 were considered to be resistant.
Two (1%) (Seedling stage) genotypes and 15 (5%) (Adult stage) genotypes were resistant to Pgt. The resistance genotypes identified in this study can be used in breeding programs. SNP markers will be identified for stem rusts resistance identified in the landrace population.
Research centre SELTON
Alena,Hanzalova, Jaroslav, Matyk, Pavel, Bartos, , , , , , , , , , , , , , , , , , , , , , , ,
In the Czech Republic all three rust species on wheat occur. Leaf rust (Puccinia triticina) can be found almost everywhere, and it can cause yield losses up to 40% mainly in warmer parts of the country in South Moravia.
Yellow rust, typical for cooler climate, occurred in relatively long time intervals. However in 2013 new pathotypes tolerating higher temperatures occurred and caused yield losses. In 2016 yellow rust incidence was lower, being still important in Moravia, where yellow rust occurred already in previous years.
Stem rust incidence was very rare in the last years. However in Germany, outbreaks and new pathotypes (e.g. Digalu) of stem rust in 2013 were recorded and comeback of stem rust to Central Europe can be expected.
Rust control consists of chemical control and especially of breeding for resistance, that aims at combined resistance to all three rusts. On the scale 9 high resistance, 1 high susceptibility average 4 year rating (2013-2016) of the tested cultivars was 6.4 for yellow rust, 5.7 for leaf rust and 6.2 for stem rust.
"Triple rust resistance" was recorded in spring wheat LOTTE and winter wheat line SG-S 1684 13, high resistance to yellow rust and stem rust in the cultivar Steffi. Resistance to all three rusts of 14 winter wheat cultivars and 12 breeding lines from the Plant Breeding Station-Stupice is summarized on separate tables and described in the text.
School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana-141004 India
Ahmed,Elkot, Satinder, Kaur, Parveen, Chhuneja, , , , , , , , , , , , , , , , , , , , , , , ,
Stripe rust and leaf rust are two most widely distributed diseases of wheat despite the fact that major emphasis has been made globally to develop rust resistant varieties. The wild tetraploid wheat Triticum araraticum (AAGG) evolved in the eastern part of Fertile Crescent is a source of useful traits for the improvement of wheat including resistance to disease. T. araraticum acc. pau4692 and a derived advanced backcross introgression line (IL) in susceptible T. durum cv. Malvi local background showed high level of seedling resistance against Indian pathotypes of leaf rust and stripe rust. The F5 Single seed descent (SSD) population developed from the crosses between T. araraticum IL with T. durum cultivar PBW114 was screened with commonly prevalent pathotypes of leaf rust and stripe rust in India at the seedling stage. The genetic analysis indicated that the leaf rust resistance is conditioned by two genes and stripe rust resistance by a single gene. The SSR markers mapped on A and B genome were used for parental polymorphism along with resistant and susceptible bulks for leaf rust and polymorphic markers between bulks were used on the whole population. The molecular marker data using single marker analysis showed that leaf rust resistance genes were mapped on chromosome 2A and 7A linked to SSR markers Xwmc149 and Xbarc49, respectively. The genes have been temporarily named as LrAr1 and LrAr2. Bulked segregant analysis (BSA) for mapping stripe rust resistance is in progress.
Tel Aviv University
Assaf,Distelfeld, , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Intensive breeding and replacement of traditional landraces by modern cultivars led to the narrowing of genetic variation in cultivated wheat. The most sustainable method for wheat improvement is utilization of genetic diversity from wheat wild relatives such as Aegilops speltoides that has a diversity of genes for resistance to leaf rust (LR). A high pairing-inducing Ae. speltoides strain collected from Israel was introgressed into T. turgidum subsp. durum var. landrace Nursi. The F1 plants were treated with colchicine to induce chromosome doubling. The resulting hexaploid plants were crossed to bread wheat cv. Beit-Lehem and F3 plants were backcrossed three times to bread wheat cv. Barnir. Each generation was selected for LR resistance to P. triticina isolate #1010 and five resistant wheat-Ae. speltoides introgression lines (ILs) designated DK1 to DK5 were selected. These Ae. speltoides ILs were genotyped using the 90K Infinium SNP assay and most of the polymorphic markers were mapped to chromosome 1B suggesting that the Ae. speltoides introgressions encompass most of this chromosome. To test if the newly identified gene is identical to Lr51, that was also introgressed from Ae. speltoides to chromosome 1B of bread wheat, the DK ILs were genotyped with the molecular marker AGA7 that was shown to be linked to Lr51. The Ae. speltoides AGA7 allele was absent in the DK ILs suggesting that these genotypes are not carrying the Lr51 introgression. Moreover, we performed an allelism test. Spring wheat cv. Kern harboring resistance gene Lr51 was crossed with DK2 and an F2 segregation ratio of 15R:1S was obtained, indicating that the resistance was conditioned by two independent dominant genes. Overall, our results suggest that DK2 carries a new leaf rust resistance gene from Ae. speltoides and this gene has potential for wheat improvement.
Wheat Diseases Department Plant Pathology research Institute, Agriculture Research Center.
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Improvement of wheat (Triticum aestivum L.) is a major goal of plant breeders and pathologists to ensure food security and self sufficiency. Relationship between different levels of stem, stripe and leaf rust severity on the two grain yield components (1000-kernel weight and plot yield) were studied during 2015/2016 and 2016/2017 seasons at Sids Agricultural Research Station. Different epiphytotic levels of stem, stripe and leaf rust were created using spreader artificial inoculation and spraying the fungicide Sumi-eight. To create different rust severity, one, two, and three sprays were applied at 7 day intervals. Protected control treatment was obtained by spraying the fungicide four times. Correlation coefficient (R<sup>2</sup>) analysis depicted that positive correlation was found between different rust severity levels and yield loss. In 2015/2016 growing season, which stem rust started early, disease severity (%) reached its relatively high percentage (80%) with the highest loss (%) in both 1000 kernel weight (36.3%) and plot weight (37.82%). The effect of stripe rust infection on yield components was lower than those of stem rust and lowest in leaf rust. On the other hand, the lowest loss was observed with 10% of stem, stripe and leaf rust which sprayed three times. During 2016/2017 stripe rust infection caused the highest loss (%) in yield components, under the highest level 80% of severity, on the other hand leaf rust showed low level of loss (%) Compared with the stripe and stem rust.