Omsk State Agricultural University, Omsk, Russia
Elena Salina, Yuriy Zelenskiy, Alma Kokhmetova, Mehran Patpour, Mogens Hovmøller, Pablo Olivera, Les Szabo, Yue Jin, Marcel Meyer, Chris Gilligan, Matthew Hort, Dave Hodson, Alexey Morgunov
Short season, high latitude spring wheat is grown on 7 million ha in Western Siberia and 10 million ha in Northern Kazakhstan. Despite relatively low wheat yields (1.5 t/ha), the region is extremely important for regional and global food security. Leaf rust dominates, occurring three years out of five, especially in favorable years with higher rainfall. Since 2010, stem rust has been observed at an increasing number of sites. The first large-scale stem rust outbreak occurred in 2015 and affected about 0.5-1 million ha in Omsk, Western Siberia. In 2016, 2 million ha were affected in the Omsk and Altay regions, while 1 million ha in the Kostanay and Northern Kazakhstan regions were affected in 2017. Estimated yield losses reached 25-35% each year. Factors associated with the outbreaks included: higher rainfall in late June and July; cultivation of susceptible varieties; and an increased area planted to winter wheat, which serves as a source of inoculum. Sampling and race analysis revealed a diverse pathogen population, indicative of a sexual recombination. A total of 51 races were identified from 31 samples taken in 2015 and 2016. All races were avirulent on Sr31. The majority of varieties released and cultivated in the region are susceptible to stem rust and require replacing. A recent study of 150 local resistant varieties and breeding lines indicated that the genetic basis of resistance was limited to Sr25, Sr31, Sr36, Sr6Ai, Sr6Ai#2, and additional unknown major genes. Adult-plant resistance to stem rust was observed in less than 20% of the germplasm. The potential impact of these large stem rust outbreaks on other wheat growing regions is being investigated by analyzing spore wind dispersal patterns. Further research is required to understand and mitigate the sudden appearance of stem rust as a disease of economic importance.
Study at Omsk State Agrarian University was supported by the Russian Science Foundation (project No. 16-16-10005).
The University of Jordan
Ayed Al Abdallat, Monther Tahat
Studies on whet stem rust (WSR) in Jordan are considered to be old. There was only one study conducted in the late 1980's by Abu-Blan and Duwayri (1989) to evaluate the infection of wheat cultivars with black stem rust disease (Puccinia graminis f. sp. tritici). Recently, reports of stem rust were published in Israel and Lebanon in 2010 and first report of Ug99 was reported in Egypt in 2014. The objectives of our research are to: (i) survey wheat growing areas for WSR in Jordan during the years 2017-2020, (ii) identification of WSR races isolated from Jordan morphologically and molecularly, (iii) analyze rust populations in terms of their response to known differential sets, pathotype distribution and diversity, (iv) screening the response of Jordanian wheat germplasm to the identified WSR strains, and (vi) study the population diversity of WSR races using RT-PCR and SNP genotyping. In 2017 a total of 270 fields of wheat and barley in the wheat and barley growing areas in Jordan were surveyed from March-May. The survey covered northern, middle, and southern parts of Jordan (arid and semi-arid regions). Altitude, longitude, and latitude data was recorded. Only few WSR pustules (n=4) were collected because the environmental conditions were not suitable for the disease to develop. On the other hand, wheat stripe rust was very common in the wheat growing areas mainly at the southern parts of the country. Other fungal plant pathogens were also reported including smuts, spots, blotches, powdery mildew, crown rot, fusarium head blight, and flag smut.
Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-University of Bonn
Mohammad Wali,Salari, Kobra, Yusefi, Mohammad, Yusefi, Gul Mohammad, Ajir, Wakil Ahmad, Sarhadi, Jens, L?on, , , , , , , , , , , , , , , , , ,
Bread wheat is a staple food in Afghanistan. Breeding for improving yield and its components in Afghan bread wheat without using new molecular methods such as marker-assisted selection (MAS) and quantitative trait loci (QTL) mapping approaches is difficult. Therefore study of genetic analysis by focus on yield and its components as first steps is necessary. Genetic analyses were performed on a winter wheat core collection of 20 accessions and commercial varieties sampled from different regions of Afghanistan and twenty agronomic traits were evaluated over three years under fully irrigated, rain-fed and drought treatments. Grain yield was the most important trait to water deficit and was highly correlated with other agronomic traits. The germplasm was structured into two sub-populations. Field plots of the genotypes were treated to one of three treatments including full irrigation, rain supplied and rain-sheltered. A randomized complete block design with three replicate was used every year of the trial. For every agronomic trait, variance components, heritability (h2) and genetic correlations was calculated. Results of the study showed that these genotypes may be good source for national breeding programs. The multiple statistical in this study showed that results of genetics correlation and regression analysis are same. Further analysis of these traits with additional experimental data to attain persuasive conclusion is suggested.
State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, P. R. China
Qilin,Wang, Jianhui, Wu, Qingdong, Zeng, Lili, Huang, Dejun, Han, Zhensheng, Kang, , , , , , , , , , , , , , , , , ,
The combination of several additive, partial resistance genes has been proposed as a preferred strategy to breed wheat cultivars with acceptable levels of durable resistance. The German winter wheat cv. Centrum has displayed high levels of adult plant stripe rust resistance (APR) in field environments for many years. One hundred and fifty one F2:7 RILs were developed from a cross between susceptible landrace Mingxian169 and Centrum to determine the inheritance of the APR resistance. The RILs and parents were evaluated for maximum disease severity (MDS) in the field during the 2015-2016 and 2016-2017 cropping seasons. Affymetrix 35K single nucleotide polymorphism (SNP) arrays were used to genotype the RILs and parents. In addition, the 660K SNP array was used to genotype bulked extreme pools and parents for saturation mapping. Four stable QTL were detected in all tested environments using inclusive composite interval mapping (ICIM); namely QYrCEN.nwafu-4AL, QYrCEN.nwafu-4BS, QYrCEN.nwafu-7BL, and QYrCEN.nwafu-7DS. QYrCEN.nwafu-4BS and QYrCEN.nwafu-7DS were contributed by MX169, QYrCEN.nwafu-4AL and QYr-CEN.nwafu-7BL were contributed by Centrum. QYrCEN.nwafu-7BL and QYrCEN.nwafu-4AL appear to represent new APR loci based on map comparisons. QYrCEN.nwafu-4BS contributed by MX169 also seems to represent a new locus. QYrCEN.nwafu-7DS is likely Yr18. Although MX169 was fully susceptible in our nurseries it is positive for the widely used marker csLV34. Reference lines carrying Yr18 are moderately resistant. Our hypothesis is that MX169 probably carries the inhibitor reported in Chinese landrace varieties by Wu et al. (2015, Plant Breeding 134: 634-640). SNP markers within these QTL were converted to KASP markers and validated in a subset of 120 diverse lines. These KASP markers should be useful for marker-assisted selection to improve stripe rust resistance in breeding programs.
Wheat Disease Research Department, Plant Pathology Research Institute, Agricultural Research Center, Egypt.
Wasif Youssif, Mohamed Hasan
Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici, [Pst] is a widespread and damaging disease of wheat (Triticum aestivum L.), causing significant losses in yield and quality. During the 2015, eight stripe rust physiological races were identified in greenhouse tests i.e. 0E0, 6E4, 70E20, 128E28, 134E244, 143E245, 250E174, and 450E214. Race 0E0 was the most common and avirulent race, and races 143E245, and 450E214 had high virulence on most of tested Yr resistance gene wheat lines. In the same season, an unusual stripe rust infection occurred in spring wheat at Sakha region in Egypt. Some of the most important commercial cultivars such as (Misr 2, Giza 168 and Sakha 61), known as resistant to the previously characterized races of Pst in Egypt have become susceptible under field conditions. Infections of stripe rust was observed on some wheat lines with Yr genes previously known to be resistant, such as Yr1, Yr17 and Yr32, in a yellow-rust trap nursery at Sakha (30.601400? N, 31.510383? E), northern Egypt. Independent race analysis of collected samples from four governorates i.e. Kafrelsheikh, Al-Sharqia, Dakahleia and Damietta at Sakha Agricultural Research Station in Kafrelsheikh confirmed the detection of a new Pst race in Egypt. Aggressive races with virulence to Yr27 were detected on differentials with Yr27 (Yr27/6*Avocet S), and (Ciano 97) during the 2012 in Egypt. In addition, the Warrior race (virulent on: Yr1, Yr2, Yr3, Yr4, Yr6, Yr7, Yr9, Yr17, Yr25, Yr32, and YrSp) was observed in the 2015 crop season, which indicated continued changes in the Pst the population. In Europe, the Warrior race first identified in 2011 in the United Kingdom, has caused significant change in yellow rust susceptibility of several varieties of both wheat and triticale. In a conclusion, some of wheat cultivars, known to be resistant, were shifted to susceptible due to these new races.
The University of Agriculture, Peshawar, Pakistan
Muhammad Khan, Aamir Iqbal, Sher Nawab, Sohail Ahmed, Muhammad Imtiaz, Sajid Ali
Resistance breeding for wheat leaf rust requires testing of breeding materials under field conditions, which must be complemented with diagnostic molecular makers. A set of 28 exotic wheat lines from advanced CIMMYT material along with three check varieties (Siran, Atta-Habib, Ghanimat-e-IBGE) were tested at three contrasting locations (Peshawar, Mansehra and Lakki-Marwat) and were genotyped with markers linked to three Lr genes (LrPr, Lr37, and Lr34). The overall leaf rust pressure was low during the wheat season of 2015-16, with the maximum disease observed at Lakki-Marwat (up to 70%), followed by Peshawar (up to 50%) and the minimum disease at Mansehra (up to 30%). Despite the overall low leaf rust pressure, the germplasm behaved variably in terms of leaf rust resistance as revealed through average co-efficient of infection (ACI). According to ACI value, 16 out of 28 genotypes were completely resistant, while few genotypes showed partial resistance. The maximum CI value was recorded for wheat line W-SA-87, which was 55 at Lakki Marwat, 33 at Peshawar and 15 at Mansehra, while 18 lines had CI value of zero across the three locations. Variability existed in yield parameters with W-SA-84, W-SA-78 and W-SA-79 producing the better grain yield. Genotyping with Lr linked markers viz., STS-7 (LrPr), SC-Y15 (linked with Lr37) and csLV34 (linked with Lr34) revealed that among the tested lines LrPr was the most frequent (83.8%), present in 26 lines; followed by Lr37 (77.4%), present in 24 lines, while Lr34 was present in 16 lines (71.1%). All three genes were detected in 45% of the germplasm. Cluster analysis grouped the germplasm in four clusters based on both phenotypic and molecular markers data. The information generated in the present study would be valuable in resistance breeding for a better control of leaf rust disease in Pakistan.
CSIRO Agriculture and Food, Australia
Timothy Hewitt, Peng Zhang, Zacharias A. Pretorius, Narayana Upadhyaya, Rohit Mago, Sambasivam Periyannan, Xiuying Kong, Burkhard Steuernagel, Brande H. Wulff, Evans S. Lagudah
Multiple rust resistance gene combinations are considered as a practical solution for providing durable rust resistance and preventing resistance breakdown arising from single gene deployment. The stem rust resistance locus Sr26, originally derived from Thinopyrum ponticum and introgressed into wheat as a chromosome translocation, is one of the very few genes conferring durable resistance for almost 40 years to all known races of stem rust, including the highly virulent stem rust race Ug99 (TTKSK) and its derivatives (Dundas et al. 2015). To understand the underlying mechanisms of its unusual long-term effectiveness and to explore allelic diversity in different Th. ponticum accessions for other functional alleles that may offer new sources of resistance, we used comparative genomics and gene capture techniques (Resistance gene enrichment sequencing, RenSeq) as complementary strategies for isolating the target gene (Steuernage et al. 2016). Sr26 region was first mapped using NB-LRR (Nucleotide-binding site and leucine-rich repeat) sequences from the orthologous gene members located on the long arm of chromosome 6D from Aegilops tauschii (the D-genome donor of wheat) reference genome. Subsequently, we revealed a cluster of NB-LRR sequences located at the distal end of the Th. ponticum introgression segment that were absent in the smallest interstitial Sr26 deletion mutant. Therefore, we substantially narrowed down the genetic interval for Sr26. In addition to this approach, we subjected the mutant population to RenSeq pipeline. A candidate gene of Sr26 has been successfully identified to be a NBS-LRR type resistance gene. Validation of the gene candidate by complementation studies is currently in progress. In order to enhance durable resistance, genetic stocks of Sr26 from different backgrounds as well as a panel of Sr26-APR (Adult Plant Resistance) gene combinations have been generated to further investigate the resistance response of Sr26 in combination with different multi-pathogen APR genes.
Department of BioEngineering, Birla Institute of Technology, Mesra, Ranchi, India
Manish Kumar, Kunal Mukhopadhyay
Bread wheat (Triticum aestivum L.) being the world's most popular edible cereal, plays a major role in global economy. Rust in wheat leaves, caused by Puccinia triticina, affects grain quality and severely retards its production worldwide. Micro(mi)RNAs are considered major components of gene silencing and so have a great role to play during stress. The present study focuses on identification of miRNAs, produced by host to suppress pathogen as well as delivered by pathogens to encounter host defence mechanism. Therefore, these miRNAs may be called as leaf rust responsive microRNAs. Small RNA and degradome libraries were prepared from a pair of near isogenic lines of wheat (HD2329, HD2329+Lr24), one set was mock inoculated while the other set was inoculated with urediniospores of leaf rust pathogen. Using these libraries as input a vast number of miRNAs rather a population of miRNAs were identified derived from wheat that were targeting genes mostly involved in functions like defense response, signal transduction, development, metabolism, and transcriptional regulation.
When reads specifically produced under pathogen inoculation were taken as input with Puccinia triticina genome sequences as reference, only three putative miRNA precursor loci were detected and the molecules produced were called miRNA-like molecules as their precursors lacked one or two criteria essential for a true miRNA precursor. The identified miRNAs were targeting genes like F-box protein, MAP kinase, calmodulin and susceptible antioxidant protein. We further identified the presence of argonaute and dicer like domains in Puccinia proteome available at FungiEnsembl which strengthens presence of RNAi-like activities in Puccinia.
In addition, differential expression of wheat as well as Puccinia small RNAs using stem loop RT-PCR under varying time points of disease progression (0-168 hpi) revealed their direct connection with stress responses.
Cereal Laboratory, Wheat Research Institute, Faisalabad, Punjab, Pakistan
Hira Shair, Anjum Javed, Muhammad Abdullah, Makhdoom Hussain, Javed Ahmed
Globally, more than two billion people are undernourished in the world and deficient in key vitamins and minerals, making it the world's greatest health risk factor. Among these, iron and zinc are of greater significance from human nutrition perspective, ranking them 5th and 6th in developing countries. The population most vulnerable to these micronutrient deficiencies is women and children. Iron deficiency results about 1.62 billion people as anemic, largely preschool children (47%). It is responsible for approximately 20854 deaths and two million disability adjusted life years (DALYs) among children under five years old, whereas, zinc deficiency is responsible for approximately 4% of deaths and 16 million DALYs, among children under age five. This leads to malnutrition ultimately leading to a disabled society.
Widespread accessibility of these nutrients is the solution to cater malnutrition. Wheat, the "staff of life," consumed by masses can help eradicate "hidden hunger." For this, fortification and bio-fortification are highly talked about, but one having limitations in reaching the masses and other a long term intervention, respectively, suitability of planting times to screen out varieties high in zinc and iron, is an on-field solution. In a study, wheat varieties; Punjab-11, Millat-11 and Galaxy-13 were selected from three planting times, with an interval of one month. Results reveal varieties exhibited their natural genotypic response but planting time impact on Zn and Fe were visibly significant. 30th December gave higher contents of Fe and Zn as compared to previous planting dates of the same year. Iron on an overall basis ranged from (135.0-147.0) ppm, while Zinc gave a confined range of (30.2-33.2) ppm. Thus, concluded that comparatively delayed sowing favours the mineral content concentration in wheat grains. And these creamed out varieties can readily be used in crosses with high yielding varieties, in order to make our wheat mineral sufficient.
The University of Agriculture, Peshawar, Pakistan
Muhammad,Khan, Safi, Kathi, Zahoor, Swati, Manzoor, Hussain, Annemarie, Justesen, Muhamamd, Imtiaz, , , , , , , , , , , , , , , , , ,
Considering the importance of wheat rust diseases in Pakistan and the recent identification of yellow rust pathogen (Puccinia striiformis f. sp. tritici) centre of diversity in Pakistan, the present study was designed to assess the status of three wheat rusts across the country during 2015-16 and 2016-17 and analyze the population structure of P. striiformis f. sp. tritici . A total of 451 fields (from 68 districts) were surveyed during 2016 and 480 fields (from 69 districts) during 2017. A high yellow rust pressure was present during 2016 throughout Pakistan, while it was predominant only in the Northern half during 2017. Leaf rust was present in the central part of the country, while stem rust was only found in the south. In Sindh province (located in the south), yellow rust was reported unexpectedly with high severity (>60%) on varieties like Kiran and Galaxy during both the years. A set of 513 samples of P. striiformis were genotyped with microsatellite markers to assess the population diversity and spatial structure. and infer on the cause of epidemics in the Sindh province. Population genetics analyses confirmed a recombinant population structure across all locations except the Sindh province, where relatively lower diversity and lack of recombination signature was revealed. At least five genetic groups were identified in the overall population, which were found across all locations, except Sindh province where one of the genetic groups was predominant. The P. striiformis population from Sindh province with low diversity that caused unexpected epidemics in a relatively warmer region needs to be further investigated for specific adaptation traits. Our results confirmed the high diversity across Pakistan, which lies in the Himalayan centre of diversity of the pathogen. This high diversity was present in locations without the presence of alternate host (Berberis spp.) and could potentially be associated with regular migrants from the Berberis zone into the whole country.