Jianping Zhang, Peng Zhang, Robert Park, Narayana Upadhyaya, Robert McIntosh, Sambasivam Periyannan, Brande Wulff, Burkhard Steuernagel, Evans Lagudah
Evolution of rust pathogens continues to pose challenges to global wheat production. Major resistance (R) genes, which encode proteins of the NBS-LRR (Nucleotide-binding site, leucine-rich repeat) family, have been a valuable resource for breeders to minimise yield losses from infection. Many wheat varieties harbor numerous R genes that could be identified and cloned in order to engineer more sustainable disease control. The advent of targeted gene enrichment and next-generation sequencing (NGS) has allowed rapid cloning of specific R genes, thus enhancing efforts to pyramid these genes and investigate their underlying resistance mechanisms. Several R genes present different phenotypes in certain genetic backgrounds, and cloning them would be an important step towards uncovering their interactions. Hybrid necrosis is one such phenotype observed in crosses of wheat genotypes involving the R gene Lr13 and complementary genes, Ne1 and Ne2, occurring in different allelic forms. It was recently concluded that Lr13 and an allele of Ne2 are actually the same gene based on genetic and mutational studies. The capability of Lr13 to confer both leaf rust resistance and hybrid necrosis cannot be answered without first cloning it. The lack of tightly linked markers coupled with the proximal 2BS chromosomal location of Lr13 does not make it easily amenable to map-based cloning. The NGS-based pipeline MutRenSeq (mutagenesis and R-gene enrichment sequencing) was used on EMS (Ethyl methanesulfonate) induced, susceptible Lr13 mutants along with support from comparative genomics to ascertain candidate gene sequences for Lr13, which are at advanced stages of screening and confirmation. Definite proof that a single gene is involved will only come with transformation studies when the cloned Lr13 candidate transformed into a susceptible line confers both a resistance phenotype in the transgenic line and a necrotic phenotype in the offspring of crosses between the transgenic line and a line possessing Ne1.
Sathguru Management Consultants
Kanan,Vijayaraghavan, Vijay, Paranjape, Richa, Kapur, Vignesh, Vilayanur Jayaraman, , , , , , , , , , , , , , , , , , , , , ,
Wheat is one of the most important food crops of the world. India is the second largest producer of wheat, currently producing 95 million tons from about 30 million hectares. Looking ahead to 2050, India needs to constantly increase production to about 150 million tons, to meet the rising population and demand. With area under cultivation having no room for growth, productivity will be the main pillar for growing production. Currently India?s yield of 3.1 t/ha has plenty room for growth as compared to the world leaders such as France (7.5 t/ha), Germany (7.3 t/ha) and UK (6.6 t/ha). Wheat productivity depends on multiple factors, seed being one of the most important.
The current operating environment is characterized by wheat R&D in the country conducted by public institutes, but there are clear signs of an emerging private sector involvement. The government promoting Inter-institutional linkages by way of associating private players in research and seed production.
This study evaluates and reflects on the current situation of the wheat seed sector in India - from research, variety/hybrid development, seed production, indent to distribution, the players involved, the challenges therein, upcoming technologies and the way forward.
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.
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.
Tel Aviv University
Assaf Distelfeld, Jacob Manisterski, Pnina Ben-Yehuda
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.