Institute of Plant Protection, Chinese Academy of Agricultural Sciences
Jing Feng, Ruiming Lin, Fengtao Wang, Qiang Yao, Qingyun Guo, Shichang Xu
Wheat stripe rust is an important air borne disease caused by Puccinia striiformis f. sp. tritici, and seriously threatens the safety of wheat production. Breeding and utilization of resistant varieties is the most economical, safe and effective measure to control wheat stripe rust. Sifangmai is a landrace from the state of Guangxi, China, and maintains good resistance to the current epidemic species CYR34, CYR33, CYR32 and CYR29 in China. Sifangmai was crossed with Taichung 29 to obtain F1, F2 and F2:3 to analyze its character of inheritance. In the adult stage, the cross of Sifangmai /Taichung 29 was inoculated by CYR32. The genetic analysis showed that the resistance of Sifangmai to CYR32 was controlled by a dominant gene, named as YrSF. A mapping population of F2 was genotyped with simple sequence repeat (SSR) markers. SSR loci Xgpw8015, Xgpw4098, Xwmc73, Xgpw8092, Xgpw7309 and Xbarc89 on 5B chromosome showed polymorphic between Taichung 29, Sifangmai, and resistant and susceptible pools, indicating that the resistant gene in Sifangmai was located on the 5B chromosome. The linkage map of these SSR markers was constructed and the nearest SSR to the gene is Xgpw8015. A set of Chinese Spring nulli-tetrasomic lines was used to confirm YrSF on chromosome 5B. YrSF is different from known genes in chromosome 5B. Xgpw8015 can be used as a marker for detection of YrSF.
Wheat Diseases Department Plant Pathology research Institute, Agriculture Research Center.
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.
Levent Ozturk, Ismail Cakmak
Zinc (Zn) deficiency is an important health problem worldwide, affecting about two billion people, especially children and women. Zinc deficiency related diseases are more prevailing in developing countries because populationa rely on cereals (i.e., wheat, rice and maize) as a staple food which are inherently low in micronutrients. Zinc concentration in cereal grains can be improved by genetic or agronomic biofortification. Optimized applications of soil and foliar Zn fertilizers has been found effective for cereals like wheat and rice but not significantly in maize. Current study focuses to elucidate the physiological reasons behind the poor response of maize to foliar applications compared to wheat. Experiments with stable isotope of Zn (70Zn) revealed the differences in leaf uptake, root and shoot translocation of foliar-applied Zn in wheat and maize. The results suggested that wheat has greater capacity for leaf absorption and translocation of foliarly applied Zn compared to maize. The increased leaf Zn uptake and localization in wheat was confirmed by a visual demonstration using Zn-responsive fluorescent dye Zinpyr and fluoresce microscopy. This study provides valuable information to maximize the uptake and deposition of foliarly applied Zn to cereal grains.
CREA-Research Centre for Cereal and Industrial Crops
Elisabetta Mazzucotelli, Oadi Matny, Antonietta Saccomanno, Raffaella Battaglia, Francesca Desiderio, Agata Gadaleta, Nicola Pecchioni, Pasquale De Vita, Giovanni Laido, Luigi Cattivelli, Brian Steffenson
The recent emergence of new widely virulent and aggressive strains of rusts (particularly stripe and stem rust) is threatening Italian durum wheat (Triticum turgidum L. var. durum) production, especially under the trend of higher temperature and humidity. A big effort has been undertaken to explore the genetic variability for resistance to these fungal pathogens and discovering novel resistance genes. In particular, a wide set of tetraploid wheat lines was genotyped with several thousands of SNP markers and used for association mapping. This large collection consisted of a group of durum wheat cultivars, produced from the beginning of the last century up to now, a collection of wild emmer wheats (T. dicoccoides), and lines belonging to other wild and domesticated tetraploid subspecies, as a large untapped source of genetic diversity. In a tight cooperation with the University of Minnesota, this collection was evaluated for reaction to several races of stem and stripe rust pathogens in both controlled greenhouse and field conditions. Among the genotypes belonging to the collection are parents of segregating populations which were used for the validation of mapping results. Novel resistance loci were identified, that can be incorporated into new durum varieties through breeding programs. The QTLs found in this study, together with those available in literature, were projected to the recently sequenced durum wheat genome in order to define more precisely the chromosome regions and candidate genes involved in resistance to rusts. Lines which were resistant to multiple races of rust pathogens were also found among both T. dicoccoides and durum wheat cultivars as a source of resistance genes, whose cloning will be undertaken based on the results here obtained.
This study was supported by the Italian Ministry of Foreign Affairs and International Cooperation, with the special grant RES-WHEAT.
State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling
Lijing Pang, Pu Yuan, Shoujun Hu, Jie Liu, Zhensheng Kang
Pathogens, whatever their types, develop at the expense of the nutrients generated by host and it is largely assumed that classical sources turn into sinks when colonized by pathogens. Sugar appears to be the major carbon and energy source transferred from the host to pathogens. Uptake, exchanges and competition for sugar, at biotrophic interfaces, are controlled by membrane transporters and their regulation patterns are essential in determining the outcome of plant-fungal interactions. However, mechanisms of transport and transporters involved in carbon partitioning between organisms are still poorly understood.
In this study, a wheat sugar transporter protein (STP) gene, TaSTP1, was cloned from a wheat-Puccinia striiformis f. sp. tritici (Pst) interaction cDNA library. Transcripts of TaSTP1 were up-regulated in wheat leaves that were infected by Pst or had experienced exogenous ABA and certain abiotic treatments. Heterologous mutant complementation in Saccharomyces cerevisiae revealed that TaSTP1 transports a broad-spectrum monosaccharides including glucose, fructose, mannose and galactose. Transient expression in Nicotiana benthamiana and Arabidopsis protoplasts suggested that TaSTP1 is localized in plasma membrane. Yeast two hybrid and bimolecular fluorescence complementation (BiFC) validated oligomerization of TaSTP1. Knocking down TaSTP1 using the barley stripe mosaic virus-induced gene silencing system reduced the susceptibility of wheat to the Pst virulent pathotype CYR31. Hyphal abnormality was significantly observed in VIGS plants. These results suggest that TaSTP1 may directly or indirectly participate in sugar transport in the wheat-Pst interactions and exert influence on suagr supply of Pst.
Ethiopian Institute of Agricultural Research, Debre Zeit Research Centre
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Stem rust caused by Puccinia graminis f.sp. tritici is one of the major biotic constraints of wheat production. The disease may cause substantial quantitative and qualitative yield losses. However, much of the work in Ethiopia on this pathosystem focuses on quantitative yield loss and qualitative losses are often overlooked. Hence the current research was designed with the objectives to evaluate the effect of stem rust on physical and chemical quality of durum wheat and assess the relationships between disease intensity and quality parameters. For this purpose, a factorial field experiment was conducted at Debre Zeit Agricultural Research Centre during main and off seasons of 2016/17. The experiment involved six durum wheat varieties (Denbi, Hitosa, Tob.66, Mukiye, Ude and Mengudo) with different level of resistance to stem rust, and three Tilt spray schedules of Tilt?250 E.C at 7, 14 and 21 days. The experiment was laid out in randomized complete block design in factorial arrangements with three replications and untreated checks were included for comparison purpose. Results revealed significant variations in disease parameters and crop performance among spray schedules, wheat varieties and their interactions. Stem rust severity was the lowest on moderately susceptible and susceptible varieties treated with the Tilt at 7th day schedule. The highest stem rust severity (46.67%) was recorded on variety Hitosa without Tilt spray. Without Tilt treatment Denbi variety accounts protein content of 15.67% which is a false protein. At 7th day spray schedule this variety showed 12.90 % of grain protein content which is normal. There was a significant positive correlation between grain protein and stem rust severity (0.31**). There was significant negative relationships between terminal stem rust severity and thousand kernel weight, hectolitre weight, seed size and yield during off and main seasons were resulted, respectively.
Ethiopian Institute of Agricultural Research
Information about changes associated with advances in crop breeding is essential for understanding yield-limiting factors and developing new strategies for future breeding programmes. Thirty-six durum wheat varieties released since 1966 were evaluated in three replications of the Randomized Complete Design at Debre Zeit and Akaki, Ethiopia during the 2016 cropping season to estimate the amount of genetic gain made over time in grain yield potential, yield-associated traits and in protein content. Analysis of variance revealed significant differences among varieties for all 16 quantitative traits, protein content and protein harvest in Kg ha-1 at each of the locations. Grain yield varied between 1.66t ha-1 for Arendato released in 1966 to 3.90t ha-1 for Megenagna released in 2012 with mean of 2.952t ha-1 at Debre Zeit. At Akaki yield range was between 2.45 and 5.04t ha-1 with mean of 3.992t ha-1. 25 varieties surpassed Arendato (3.754t ha-1) at this location. In the combined ANOVA significant difference between the varieties was observed only for spike length, spikelets spike-1, grains spikelet, grains spike-1, plant height, days to flowering, thousand grain weight and hectoliter weight. Varieties specifically adapted to only one of the locations, widely adapted varieties and varieties not adapted to any of the locations were identified. Regression analysis revealed that grain yield has increased by 22kg ha-1 year-1 since 1966; an increase of 40.6% over yield in 1966. This was accompanied with a significant decline of 11.4% in spike length, 6.7% in spikelets spike-1, 17.9% in protein content and 31.2% in protein yield ha-1 and a significant increase of 41.1% in grains spikelet-1, 32.9% in number of grains spike-1, 22.3% in thousand grain weight, 17.8% in grain filling period, 23.9% in seed growth rate, 40.1% in grain yield production rate, 7.9% in harvest index.
Fatima Gaboun, Nasserlhaq Nsarellah, Keltoum Rhrib, Atmane Rochdi
Durum wheat landraces have constituted the main source of Moroccan wheat production until the first half of the last century. This local germplasm is still cultivated in less favorable environments particularly in mountains and sub-Saharan regions. In recent decades of the late 20th and early 21th centuries, the genetic improvement had led to the release of new durum wheat cultivars highly uniform and more productive. The present paper investigates the evolution of genetic variability in terms of productivity and quality related traits using an historical series of Moroccan durum wheat genotypes grouped according to their period of release into "Landraces/ Old cultivars," "Intermediate cultivars," and "Modern cultivars". A significant improvement was achieved in durum wheat Morroccan productivity. Modern cultivars exceed their predecessors in terms of productivity related traits. The genetic gain was clearly associated with a reduction in plant cycle and plant height lowering the straw yield which resulted in an increase of grain yield estimated to 15.42Kg/ha/year. However, results revealed a reduction in terms of almost all quality related traits; -0.12% per year for protein content, -0.30 % per year for gluten strength, -0.31% per year for yellow pigment content, and -0.19% per year for vitreousness. The results underline the important variability in grain quality attributes among landraces genotypes. This local germplasm may be used as sources of quality-improving attributes in durum wheat breeding program to develop new varieties combining both high productivity and grain quality.
Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization, Karaj, Iran.
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Stripe rust of wheat, caused by Puccinia striiformis f. sp. trirtici (Pst) is an important disease in many parts of Iran. Over last two decades several epidemics have occurred in Iran causing the breakdown of widely utilized sources of resistance in wheat cultivars. Fifty isolates were collected from different parts of Iran during 2017. Eight isolates of Pst. from 2017 have been processed to date for race analysis. Infection types were assessed on a 0-9 scale 16 and 18 days after inoculation using a scale similar to that described by McNeal et al. (1971). Infection types (ITs) 7 to 9 were regarded as virulent (susceptible) and lower than 7 were avirulent. Pathotypes 102E158A+,Yr27; 6E158A+,Yr27; 102E158A+,Yr27; 166E154A+,Yr27; 38E174A+; 38E158A+,Yr27; 238E190A+,Yr27 and 38E190A+,Yr27 were identified. Pathotype 238E190A+,Yr27+ (from West of Iran) was more aggressive during this study. Plants with Yr1, Yr4, Yr5, Yr10, Yr15, Yr24 and YrSP were resistant to all pathotypes. Pathotypes with virulence on plant with gene/s Yr2, Yr6, Yr7, Yr8, Yr9, Yr25, Yr26, Yr27, Yr32, YrSD, YrSU, YrND and YrA were more common. Seedling tests of Iranian wheat cultivars to race 238E190A+,Yr27+ showed that the new released cultivars that included Parsi, Baharan, Bahar, Pishgam, Zareh, Urom, Maihan, Dena, Haydarei and Shabrang were resistant to the new aggressive race with virulence on plants with Yr27.
The University of Queensland, Queensland Alliance for Agriculture and Food Innovation (QAAFI)
Naveenkumar,Athiyannan, Sambasivam, Periyannan, Olga, Afanasenko, Olga, Mitrofanova, Gregory, Platz, Elizabeth, Aitken, Rod, Snowdon, Evans, Lagudah, Lee, Hickey, Kai, Voss-Fels, , , , , , , , , ,
Leaf rust (LR) is an important wheat disease and deployment of resistant cultivars is the most viable strategy to minimise yield losses. We evaluated a diversity panel of 295 bread wheat accessions from the N. I. Vavilov Institute of Plant Genetic Resources (VIR), St Petersburg, Russia for LR response and performed genome-wide association studies (GWAS) using 10,748 polymorphic DArT-seq markers. The diversity panel was evaluated at the seedling and adult plant growth stages using three prevalent Australian P. triticina pathotypes. GWAS applied to 11 phenotypic data sets identified a total of 52 significant marker-trait associations representing 31 quantitative trait loci (QTL). Among them, 29 QTL were associated with adult plant resistance (APR). Of the 31 QTL, 13 were considered potentially new loci, whereas 4 co-located with previously catalogued Lr genes and 14 aligned to regions reported in other GWAS and genomic prediction studies. One seedling LR resistance QTL located on chromosome 3A showed pronounced levels of linkage disequilibrium among markers (r2 = 0.7), indicative of a high allelic fixation. Subsequent haplotype analysis for this region found 7 haplotype variants, of which 2 were strongly associated with LR resistance at the seedling stage. Similarly, analysis of an APR QTL on chromosome 7B revealed 22 variants, of which 4 were associated with resistance at the adult-plant stage. Most of the lines in the diversity panel carried 10 or more combined resistance-associated marker alleles, highlighting the potential of allele stacking for long-lasting resistance.