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).
University of Minnesota
Ayele Badebo, Worku Bulbula, Matthew Rouse, Yue Jin
Our research objective is to identify new resistance genes in durum wheat that are effective against TTKSK and other significant stem rust pathogen races that could be utilized in durum breeding. We characterized 8,000 accessions for stem rust response in the field (Debre Zeit, Ethiopia, and St. Paul, MN). Accessions with resistant to moderately resistant responses in multiple field evaluations were evaluated at the seedling stage for resistance to races TTKSK, TRTTF, TTTTF, JRCQC, TKTTF, and six representative U.S. races. We identified 438 durum accessions resistant to moderately resistant in all field evaluations. Among the field-resistant accessions, 273 were resistant to all races used in seedling evaluations. Accessions susceptible at the seedling stage are being evaluated for the presence of adult plant resistance genes. The highest frequencies of resistant lines include landraces from East and North Africa (Ethiopia and Egypt) and advanced breeding lines and cultivars from North America (Mexico and USA). DNA markers will be performed to identify the presence of durum stem rust resistance genes, including Sr13, Sr8155B1, Sr11, and Sr8a. Nineteen resistant accessions were selected to investigate the genetics of TTKSK and TRTTF resistance. Results from evaluating F2 and F2:3 generations from biparental crosses revealed that resistance to race TTKSK was conferred mostly by one or two genes with dominant and recessive actions. Additional resistance genes were identified when populations were evaluated against race TRTTF. A bulk segregant analysis approach is being used to map the resistance in selected lines using the 90K SNP platform.
University of Delhi South Campus, New Delhi
Towards understanding the molecular mechanisms of heat stress tolerance, we have analyzed heat stressed substractive cDNA libraries and undertaken genome-wide transcriptome exploration for genes associated with spike photosynthetic efficiency during thermal stress. The photosynthetic efficiencies of Aegilops tauschii and Ae. speltoides were also compared. While the former displayed nearly complete recovery of PSII, the adverse effect was more pronounced in the latter. Functional characterization of heat stress-associated transcription factors and thermal stress-associated proteins was also undertaken e.g. TaHSF, TabZIP, TaZnF and TaMIPS, and TaLTPs in the Indian wheat germplasm. Functional characterization of the three heat stress transcription factors was upregulated under high temperatures and other abiotic stresses. They also showed early flowering and better performance with respect to their growth and yield after heat stress. Additionally, we have identified various interacting components associated with thermal stress-mediated plant signaling partners during thermal stress.
University of Queensland, St. Lucia
Adnan Riaz, Jonathan Powell, Timothy Fitzgerald, Kemal Kazan, Neena Mitter, Evans Lagudah, Lee T. Hickey
The Lr34/Yr18/Sr57/Pm38/Ltn1 multi-resistance locus has been deployed and remained effective in wheat cultivars for more than 100 years. The durability and pleiotropic nature makes Lr34 a unique and highly valuable resource for rust resistance breeding. Despite its functional annotation as an ABC transporter, the mode of action is unknown. Considering this, we aimed to decipher molecular factors and signaling components essential for Lr34 function using RNA-seq of Chara resistant (Lr34) and Chara mutant (heavy ion irradiation, HII) susceptible wheat lines. Screening of Chara and Chara HII lines with Lr34-specific markers confirmed the integrity of Lr34 in both lines; however, phenotyping confirmed rust and powdery mildew susceptibility in the Chara HII lines. Plants were grown under controlled conditions and infected with Puccinia triticina pathotype 76-1,3,5,7,9,10,12,13+Lr37 at the flag leaf stage. Flag leaves were sampled at 0, 24, 48, 72, 96 and 168 hours post inoculation (hpi) from mock and infected plants. Based on real-time PCR analysis of basal defense genes and the Lr34 gene, we selected 72 hpi for RNA-seq with four biological replicates per condition. The samples were sequenced on an Illumina Hiseq 4000 at the Beijing Genomics Institute, China. A total of 9.0 Gb of sequence (2.25 Gb/library) from 16 libraries for four conditions was obtained. Differential expression analysis was performed using the Tuxedo analysis pipeline with standard parameters. Analysis revealed deletion of DNA fragments with collinear gene order on chromosomes 1A, 2D, 5A, 5B, 5D and 7D of Chara HII mutants. To determine the significance of the deletions we performed bulk segregant analyses on segregating F2 populations of Chara ? Chara HII crosses. Analyses revealed key genomic regions associated with Lr34-functional resistance and we are in the process of validating candidate genes using qPCR.
P. triticina has a biotrophic relationship with wheat and needs certain elements from the wheat host for a successful life cycle. In recent years, several long lasting, minor resistance genes have been cloned, and their function suggests that the resistance is not due to a classic NB-LRR gene, but a gene that functions in a biotrophic pathway. The hypothesis was proposed that modification of a susceptibility gene can provide broad, long lasting resistance. To test this hypothesis, Thatcher was treated with EMS and screened for changes in susceptibility. M5 lines were evaluated in the greenhouse with BBBD Race 1 and 5 lines were identified. Also, M5 lines were planted in the field to verify the resistance and test the resistance effectiveness to natural infections of P. triticina. The same five lines were resistant in the field. Resistance ranged from few pustules, a race specific-like reaction, lesion mimics with few or no pustules, and near immunity. These lines were backcrossed to Thatcher, and resistant F2 plants were bulked and sequenced. Gene candidates will be identified and discussed.
National Research Council of Canada (NRC)-Saskatoon
Kerry Boyle, Tammy Francis, Peng Gao, Brittany Polley, Christine Sidebottom, Brent McCallum, Harpinder Randhawa, Tom Fetch, Randy Kutcher, Sylvie Cloutier, Pierre R. Fobert
Most rust resistant genes in wheat are race-specific (R), with relatively few genes conferring resistance only at the adult stage that have been described as slow rusting genes (APR). Pyramiding multiple R, APR or APR+R genes has been used successfully over many years to achieve durable rust resistance. To further enhance this strategy, a genetic genomics approach was exploited to identify genes with different resistant mechanisms and the most effective gene pyramids.
Several new combinations of rust genes were created and tested in the Thatcher background, revealing synergistic ("booster") effects involving Lr21 with Lr16. With QTL mapping approach, we found that genes combined from 7D, 1B and 7B conferred an almost immune response to leaf rust, while genes from 7D, 1B and 3B provided an almost immune response to stripe rust. With a genomics approach, a large scale transcriptome analysis was conducted on key rust resistant genes including six R genes, three APR genes and one gene pyramid with Lr34+Lr16 over a time series during the infection process of both seedlings and adult plants. Detailed transcriptome analysis of gene expression associated with different major and minor leaf rust genes, alone or in combination, identified common and unique aspects of defense responses. For example, Lr9 is different from the other three leaf rust genes tested, with resistance triggered at a very early stage, consistent with pre-haustorial resistance. R genes Lr21 and Lr16 were also significantly different compared to other R and APR genes. With gene co-expression network analysis, a shared unique gene module mediated by Lr34 and Lr67 was also identified. This large transcriptome dataset also allowed the development of a rust-wheat interactome atlas for rust functional genomics research in wheat.
Agharkar Research Institute Pune
Vijendra Baviskar, Balgounda Honrao, yashavanthakumar kakanur, Vilas Surve, Deepak Bankar, Vitthal Gite, Ajit Chavan, Vijay Khade, Juned Bagwan, Shrikant Khairanar, Sameer Raskar
Frontline demonstrations (FLDs,) on wheat were conducted by Agharkar Research Institute, Pune, during last five rabi seasons from 2012-13 to 2016-17 at farmer's fields of Pune and Satara district under wheat growing area of semi-arid tropics of western Maharashtra, India. Before conducting FLDs, a group meeting held every year in the selected village and specific skill training had imparted to the randomly selected farmers regarding adoption of different improved aspects of cultivation. FLDs comprised of improved wheat varieties viz., MACS 6222, MACS 6478, MACS 3125 (d) and MACS 2971(dic) for Peninsular Zone of India. About 50 ha of FLDs on improved wheat varieties were conducted with active participation of 50 farmers covered an average of 10 farmers and 10 ha per year. Two recent varieties, MACS 6222 and MACS 6478 had shown higher grain yield, ranging between 15 to 55 per cent more over local check and farmer practice than all other FLDs. Recommended packages and practices of wheat FLDs gave higher value of yield, net return and high benefit cost ratio as compared to local check over the years of study. The study has revealed that five years mean extension gap of 4.48 to 9.67 q/ha and technology gap ranging between 11.00 to 22.22 q/ha depending on the variety during the period of study. Net returns of Rs. 63042/ha was observed from improved practice than in the farmer's practice of Rs. 50108/ha and with benefit cost ratio of 3.07 and 2.79 respectively. On average basis, the incremental benefit cost ratio was found as 2.83. In frontline demonstrations, the yield potential of wheat has been enhanced largely due to the increase in the knowledge of farming community and adoption of improved production techniques by farmers.
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.
Panjab University Chandigarh
Sterol 14?-Demethylase Cytochrome P450 (CYP51) protein involved in ergosterol biosynthesis pathways is a crucial target for efficient fungicidal compounds. However, the recognition mechanism and dynamic behavior of CYP51 in wheat leaf rust pathogen, Puccinia triticina is still obscure. Previously, a mutation at codon 134 (Y134F) was reported in five European isolates of P. triticina, the structural basis of this mutation remain unclear. To address this problem, CYP51 wild type protein and its variant proteins were successfully modeled using I-TASSER, an ab initio based structure prediction pipeline. To gain valuable insights into structure-function behavior for the binding wild-type and mutant-type proteins, individually generated protein models was subjected to 50ns molecular dynamics (MD) simulations run. Observably, this comparative protein-ligand interaction analysis and binding free energy results revealed that impact of mutation on the thermodynamics and conformational stability of the CYP51 protein is negligible. In present study, we carried out structure-based molecular docking and identified potent novel fungicidal compounds from four different databases and libraries. Consequently through MD simulation and thermodynamic integration, four novel compounds such as CoCoCo54211 (CoCoCo database),ZINC04089470(ZINC database), Allyl pyrocatechol 3,4 diacetate (Natural compound library) and 9-octadecenoic acid (Traditional Chinese Medicine database) has been predicted as potent fungicidal compound against CYP51 with XPGlidedocking score of -11.41, -12.52, -7.40 and -7.55 kcal/mol, respectively. These compounds were found to directly bond to heme group of CYP51, subsequently disturbing the stability and survival of fungus and can be used to control leaf rust in wheat.
Institute of Evolution and the Department of Evolutionary and Environmental Biology, University of Haifa, Israel
Dina Raats, Lin Huang, Valeria Bocharova, Jorge Dubcovsky, Abraham Korol, Tzion Fahima
Wild emmer wheat (Triticum dicoccoides, (DIC)) is an important source of resistance to stripe rust due to presence of Puccinia striiformis in its natural habitats with high humidity and relatively low temperatures that are favorable for stripe rust development. Previously, we showed that DIC accessions from northern Israel were highly resistant to stripe rust. According to the rust responses of three DIC accessions (G25, H52, G303) and mapping of the resistance to relatively close, but different, genetic positions on chromosome 1BS, three different resistance genes were assumed to be present. However, the development of additional critical recombinants and new higher resolution genetic maps for these three genes in subsequent work led us to place YrH52 and YrG303 in the same genetic interval as Yr15, suggesting that the three putative genes are allelic or identical. The recent cloning of Yr15 allowed us to test this hypothesis using an EMS mutagenesis approach. We sequenced the Yr15 locus in five yrH52 and three yrG303 susceptible mutants and identified missense point mutations associated with the susceptible phenotype in each one. Thus, YrH52 and YrG303 may not be new genes. Further work is under way to determine if these genes are allelic or identical.