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.
Agharakar Research Institute Pune
yashavanthakumar,Kakanur, Vijendra, Baviskar, Ajit, Chavan, Vilas, Surve, Vijay, Khade, Juned, Bagwan, Vitthal, Gite, Shrikant, Khairanar, Sameer, Raskar, Deepak, Bankar, Satish, Misra, , , , , , , ,
MACS 3949 is a durum wheat variety developed at Agharkar Research Institute, Pune derived through selection method from 39th IDYN (CIMMYT). The variety was identified by 55th All India Wheat and Barley workshop CCS HAU, Hissar and subsequently notified by Central Sub Committee on Crop Standards, India. On the basis of mean of three years (2013-14, 2014-15 and 2015-16) data from All India coordinated experiment, grain yield of MACS 3949 (43.98 q/ha) was higher to all the checks Viz., NIDW 295 (39.70 q/ha) and UAS 428 (41.78 q/ha). Overall, MACS 3949 showed a yield advantage of about 10.78 % over NIDW 295 and 5.24 % over UAS 428. The important morphological traits of the variety described as, semi dwarf with average plant height around 81 (78-83) cm, medium sized strong waxy semi erect green leaves, parallel dense spikes with long spreading awns. Grains were amber colored, bold lustrous, semi hard, elliptical in shape with short brush, soft threshing at maturity and1000-grain weight was about 47 (42-53) gm. The variety has shown resistance to leaf rusts, in particularly the seedling resistance to race 77-complex of leaf rust, stem rust, leaf blight, powdery mildew, flag smut and karnal bunt under both natural and artificial screening conditions. It has high protein content (12.9 %), better nutritional quality (Zinc 40.6 ppm, Iron 38.6 ppm) with good milling quality (Test weight 81.4 kg/hl) and best cooking quality for pasta product having highest overall acceptability 7.25. The newly developed durum wheat variety MACS 3949 released for cultivation at Peninsular Zone in India, which is having rich source of nutritional pasta quality with high zinc and iron content will be a promising one for future potential of export at international market.
National Plant Protection Center
Namgay Om, Thinlay, Ugyen Yangchen
Wheat rusts are one of the important diseases that limit the production and downgrade wheat quality. Three rust diseases of wheat are stem rust caused by Puccinia graminis Pers. f. sp. tritici Eriks., stripe rust caused by Puccinia striiformis Westend. f. sp. tritici Eriks., and leaf rust caused by Puccinia triticina Eriks. This study was conducted to determine the reaction of wheat varieties to wheat rusts at different altitudes. Field experiments were conducted from December 2016 to March 2017 at Mendagang (27.5886°N, 89.8711°E, 1332 masl), Punakha Dzongkhag (district) for mid altitude and at Agriculture Research and Development Center (ARDC), Samtenling (26.9058°N, 90.4308°E, 378 masl), Sarpang Dzongkhag, Bhutan for low altitude. The experiment followed a RCBD with 15 treatments comprising of three Bhutanese released varieties, eight SAARC varieties, and four ICARDA varieties. Each treatment was replicated three times. Assessment of disease incidence and severity were performed three times starting from tillering to ripening stage, approximately at 60, 90 and 120 days after sowing (DAS). Disease severity was determined following the modified Cobb’s disease rating scale. Of the 15 varieties, only 11 germinated in both the sites. Among the three wheat rust diseases, only leaf rust was observed in both sites. Leaf rust incidences ranged from 2.5 to 10% and 2.5 to 16% at mid and low altitudes respectively. Disease severity of 5 to 20%, corresponding to field response of immune (5O) to moderately resistant (20MR), was observed at mid altitude, while 5 to 100%, with immune (5O) to susceptible (100S), was observed at low altitude. There was a significant difference in disease incidence by site (p=.038) but not in disease severity (p=.129). The variety, ICARDA 1, with 100% severity was highly susceptible (100S) to leaf rust at low altitude while Bajosokha Kaa remained immune (5O) in both the sites. The results indicate that leaf rust can occur in both low and mid altitudes; however selection of suitable varieties requires more extensive studies.
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.
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.
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.
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.
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.
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.
The University of Georgia (UGA)
Suraj Sapkota, James Buck, Jerry Johnson, John Youmans
Leaf rust disease, caused by the fungal pathogen Puccinia triticina, is a major biotic constraint of wheat production worldwide. Genetic resistance is the most effective, economic, and environmentally safe method to control and reduce losses caused by this disease. More than 70 leaf rust resistance genes have been identified and mapped to specific chromosomes; however, continuous evolution of new leaf rust races requires constant search for new sources of resistance with novel QTL/genes. The objectives of this study were to identify sources of resistance, and to map genomic loci associated with leaf rust resistance using genome wide association study (GWAS) approach. Phenotypic evaluation of 297 spring wheat genotypes against a prevalent race of leaf rust in Georgia revealed that most of the genotypes were susceptible, and only 24 genotypes were found resistant. Furthermore, GWAS detected 10 markers on chromosomes 2A, 2B, 6A, 7A, and 7B significantly associated with leaf rust resistance. A marker on chromosome 7AS was identified revealing a novel genomic region associated with leaf rust resistance. The new identified sources of resistance and QTL could be used in wheat breeding programs to improve leaf rust resistance.