JOHN INNES CENTRENorwich Research Park, Colney, Norwich NR4 7UH, United Kingdom.
Lesley Boyd, Phil Smith, and Clare Lewis (née Ellerbrook).
Adult plant resistance to yellow rust is being examined in a number of wheat cultivars, including the U.K. cultivars Claire and Buster. In the South African wheat, Kariega, two major yellow rust-resistance QTL have been identified, one on chromosome 2B and the other on 7DS. The QTL on 7DS is believed to be the durable source of yellow rust resistance, Yr18.
Lesley Boyd, Phil Smith, and James Melicher.
The biology and genetics of developmentally regulated resistance to rusts and powdery mildews is being examined through a study of wheat mutants that express enhanced resistance to one or more of these pathogens. Mutants, isolated from the wheat varieties Hobbit 'sib' and Guardian, are being mapped to determine the number, location, and effect of each mutation contributing to each pathogen resistance. These mutant lines also are being assessed to determine their value as a source of resistance in U.K. breeding programs.
Lesley A. Boyd, and Ruth McCormock.
A new program will look at the effects on preinoculation light levels on the ability of yellow rust to infect wheat. Preliminary studies indicate that high levels of light, before inoculation, induce a factor in the plant that aids the pathogen in its ability to infect. The aims of this program are to identify this plant factor and identify genetic variation for the levels of this factor produced by wheat.
Vinesh Verma, Liz Sayers, Lesley Fish, and John Snape.
Lodging is a major constraint to increasing yield in many crops but is of particular importance in the small-grained cereals. The genetic control of lodging and component traits in wheat was investigated through the detection of underlying QTL. The analysis was based on the identification of genomic regions which affect various traits related to lodging resistance in a population of 96 DH lines of the cross 'Milan/Catbird', mapped using 126 microsatellite markers. Field experiments measured lodging behavior under natural climatic conditions, but glasshouse tests also were conducted on the physical characteristics of the stem and root mass. The co-location of QTL allowed physiological traits measured in the glasshouse and field to be related to lodging under normal field conditions.
Although major genes related to plant height (Rht genes) were responsible for increasing lodging resistance in this cross, several other traits independent of plant height were shown to be important such as root and shoot traits and various components of plant yield. Yield components, such as grain number and weight, were shown to be an indicator of plant susceptibility to lodging. QTL for lodging and associated traits were found on chromosomes 1B, 1D, 2B, 2D, 4B, 4D, 6D, and 7D. QTL for yield and associated traits were identified on chromosomes 1B, 1D, 2A, 2B, 2D, 4D, and 6A. These results show that selection for lodging-resistant genotypes can be done via indirect selection based on the morphological traits of plant height and culm stiffness before flowering. In the population here, the most efficient way to improve lodging resistance would be a combination of indirect selection on plant height, combined with MAS on other, less easy to measure, physiological traits.
Robert Koebner, John Snape, Christian Rogers, Leodie Alibert (JIC); and Kim Hammond-Kosack, Peter Shewry, and Andy Phillips (Rothamsted Research).
WGIN is a new venture, funded by the U.K. Government Department for Environment, Food & Rural Affairs, as a 5-year initiative that started in July 2003. The two research partners (John Innes Centre (JIC) and Rothamsted Research (Rres)) will collaborate to provide a suite of underpinning resources and research to the U.K. wheat-breeding industry.
The JIC contribution involves (1) the provision and enhancement of germ plasm, taking in cultivar and landrace collections, cytogenetic stocks, and mapping populations; (2) the development of novel genetic markers, particularly aimed at genic sequences and will include platforms based on SSRs, SNPs, and functional DNA fingerprinting; (3) the incorporation of both markers and selected phenotypic traits of value to the enhancement of agricultural sustainability into genetic maps; (4) the linking of the physical and genetic maps of wheat by mapping ESTs onto a hexaploid wheat BAC library; (5) the analysis of the molecular diversity of U.K. and European winter wheats to illuminate the genetic basis of 50 years of genetic advance; and (6) the generation, maintenance, and characterization of a large collection of mutagenized lines to aid in gene discovery.
The RRes contribution focuses on (1) the use of the diploid wheat T. monococcum (AA genome) as a model system to identify novel sources of resistance to major U.K. pathogens with a nonbiotrophic life-style, i.e., Septoria leaf blotch, Tapesia eyespot, Fusarium ear blight, and soilborne cereal mosaic virus and its vector P. graminis, and to develop linked markers with which to screen diverse hexaploid collections; (2) PCR tilling to explore, in a high throughput manner, the diversity that naturally resides at specific loci or which has been generated through EMS mutagenesis (This technique will be applied only to genes of known biological significance, and both diploid and hexaploid wheat genotypes will be explored. A demonstration project will be established to identify variation in genes known to control preharvest sprouting, plant height, and plant defence signalling/disease resistance to multiple pathogens in other plant species); and (3) trait identification. The selected mapping populations, their parents, and selected genotypes from the diversity screen will be subjected to field trialing to analysis for specific trait characteristics. A highly focussed list of traits to be evaluated is decided by the management team each year. In years 1-3, traits under investigation include nitrogen use efficiency, the influence of canopy architecture on Septoria leaf blotch and Fusarium ear blight diseases, and various grain quality parameters. A searchable traits database will be established and all preëxisting traits data sets archived appropriately.
The Network is guided by a management committee which includes representatives from the funding agencies, the research providers, and the end-user community. The core project will provide genetic and molecular resources for research for a wide range of wheat research projects in the U.K. An annual stakeholders forum is held to facilitate liaison between the U.K. research and end user communities. Further details of all WGIN activities and contact details are located on the WGIN website (http://www.wgin.org.uk/).
Leodie Alibert, Christian Rogers, Pauline Stephenson, and Robert Koebner.
The JIC curates the Watkins wheat collection, which consists of ~900 hexaploid accessions collected worldwide in the 1920s and 1930s. As part of the WGIN project, we are generating single-plant progeny stocks for four individuals/accession, because intra-accession heterogeneity is frequent at the morphological level. Archive DNA has been collected from these selections by leaf squash on to Whatman FTA cards, and these DNAs will be used to SSR-genotype the materials to give an overview of the inter- and intra-accession diversity of the materials. These data will form the seed of a growing database record, which is intended to be internet available and searchable.
Nicola Hart and Robert Koebner (JIC) and Peter Jack and Richard Summers (Monsanto UK Ltd).
In this new project supported by Monsanto U.K., we are seeking to investigate the relationship between the intensity of mutagenesis and the size, nature, and frequency of induced genetic lesions in wheat. We are targeting initially the rht loci by mutagenizing (with g- and x-ray) the tall, spring wheat cultivar Paragon with a range of mutagen load from below to well above the generally used dose of 250 Gy. The outcome of the mutagenesis will be monitored by analysis of a suite of amplicons covering the rht locus, exploiting both size discrimination (for deletions) and heteroduplex analysis (for sequence changes).
Andy Bottley and Robert Koebner.
This project builds on the work reported last year (Ann Wheat Newslet 49:161) in which comparisons were made between the SSCP profiles of gDNA and cDNA, to demonstrate the occurrence of silencing at some expressed sequence loci. We are extending the analysis to a larger sample of single copy EST loci, many of which have been derived from the NSF EST database. The analysis will be enabled by our acquisition of a WAVE dHPLC platform, which will generate greater resolving power than SSCP.
Simon Orford and Robert Koebner (JIC); Martin Ganal and Markus Wolf (Traitgenetics, Gatersleben, Germany); and John Law and James Reeves (NIAB, Cambridge, UK).
As part of a wider effort involving barley, potato, and maize, the EU FP5-funded Gediflux project has been involved in the collection of genotype data covering a collection of ~300 winter wheat cultivars, which represent the bulk of area sown in northern Europe in the period since 1945 and the ~200 National List cultivars (those which are legally traded). The overall collection has been typed at 42 SSR loci (one per chromosome arm), ~70 SSAP loci (derived from a retrotransposon LTR motif), and ~50 NBS fingerprint loci. Attention is now focussed on SNP genotyping. The final size of the dataset will exceed 100,000 data points, sufficient to closely model trends in diversity over time in European winter wheat. This project follows similar smaller-scale pilot projects in U.K. wheat and barley, which have been published in Theroetical and Applied Genetics 100:912 and 106:550, respectively.
Paul Nicholson, Andrew Steed, Natalie Chapman, Nicolas Gosman, Richard Draeger, Elizabeth Chandler, Martha Thomsett, and Duncan Simpson.
As part of a continuing study of FHB resistance, the resistance of Arina and WEK0609 has been analyzed by spray inoculation of DH populations. Mapping and QTL analysis of resistance also continues, and skeletal genetic maps of these populations have been produced. Single-chromosome substitution lines of WEK0609 have been produced, and three chromosomes conferring resistance have been identified. A collaborative project is underway to assess the level of FHB resistance among U.K. wheat cultivars and to introduce and pyramid FHB-resistance genes from diverse sources to improve the level of resistance among winter wheat varieties in the U.K.
The resistance of T. macha 4A, previously reported, has been investigated further in single-chromosome recombinant DH lines. Resistance on this chromosome appears to be conferred by a single gene. The resistance is primarily of type 1 and leads to reduced symptoms and accumulation of DON mycotoxin. In addition, mapping and molecular studies of two eyespot resistance genes (Pch1 and Pch2) is also being undertaken.
Molecular diagnostics (species-specific competitive PCR) are being used to study interactions between spike and stem base disease pathogens on different cereal hosts. This work is combined with continued development of molecular diagnostics to determine the chemotype of individual isolates of Fusarium species for use in epidemiological studies.
Mike Ambrose and Steve Reader.
Wheat Precise Genetic Stocks (WPGS). A concerted program of database development and record entry relating to these resources has been ongoing for the past 2 years. At present, this data is available as a Microsoft Word-based files via the JIC Web pages (http://www.jic.ac.uk/GERMPLAS/prec_ce/index.htm). A searchable web interface is under development and should soon be operational.
The Crop Genetics Department at JIC has accumulated a large collection WPGS over the last 60 years. Many are the products of research programs at both the JIC and the former Plant Breeding Institute in Cambridge, U.K. Other lines were donated freely by fellow scientists from around the world. This extended collecting period has meant that often original donors have retired or may no longer be alive. Similarly, cultural and political trends within originating countries have occasionally compromised the viability of material, such that JIC may be one of the very few sources remaining.
The collection includes the late Ernie Sears collection of aneuploids in the cultivar Chinese Spring and lines which have a pair of chromosomes from a related species added to the wheat complement, a pair substituted for their wheat homoeologues, or a pair translocated with them. Also held are numerous amphiploids, stocks that contain the total complement of both parents. The work of the late Tony Worland is represented by 23 complete or partial monosomic series and several hundred derived, intervarietal substitution lines. These lines currently are being classified and entered into the database. However, many stocks are over 20 years old, and the primary concern currently is regenerating as many as possible each year to ensure that viable stocks will exist in the future. In due course, the Crop Genetics Department's collection of wheat landraces, wheat ancestors, and related species, also will be similarly accessible.
BBSRC Small Grain Cereal Collections. A searchable web interface is now available that enables users to interrogate passport data for the collections that include the public collection of some 9,500 wheat accessions (http://data.jic.bbsrc.ac.uk/cgi-bin/germplasm/cereals.asp). The user form offers the facility to select specific species and subspecies, country of origin, and status. Records can be sorted either by accession number or name. Individual record details are still under development but already include all available pedigree data.
Wendy Harwood, Judith Irwin, and John Snape (JIC); and Huw Jones (RRes).
The ability to genetically modify crop plants is an essential part of many research programs that contribute to the understanding and improvement of UK crops. Therefore, the availability of reliable genetic modification technology is of great importance to both basic and applied U.K. crop research.
BRACT (Biotechnology Resources for Arable Crop Transformation) is a U.K. Department for Environment, Food and Rural Affairs funded project that aims to make efficient transformation technology for the main U.K. crops available to the U.K. research community. The project was set up jointly between the John Innes Centre and Rothamsted Research and initially focuses on wheat, barley, and oilseed rape. The resources developed during the BRACT project will be tailored to meet the needs of the U.K. research community and will particularly concentrate on providing precise, efficient, and robust transformation technology that takes account of the current concerns over the use of GM crop plants.
The main transformation methodology used by the BRACT facility will be Agrobacterium-mediated transformation because this method leads to lower transgene copy numbers and more stable transgenic lines. The development of 'clean-gene' transformants, where the selectable marker has been segregated away from the gene of interest, is an important part of the project together with the development of a new set of transformation vectors that will allow easy manipulation and insertion of genes of interest. As well as providing transformation technology and vectors, BRACT will provide assistance with crop transformation ranging from advice and training through to a complete transformation service.
Further information on the BRACT project can be found on the
project website http://www.bract.org/.
UNIVERSITY OF LEICESTER
Department of Biology, University Road, Leicester LE1 7RH, United Kingdom.
http://molcyt.com or http://www.le.ac.uk/biology/phh4/index.htm
Alessandra Contento, J.S. Heslop-Harrison, and Trude Schwarzacher.
About 90 members of the 120-bp, tandemly repeated DNA sequence family originally described in rye as pSc119.2 sequence have been isolated from 11 diploid and polyploid Triticeae species using various primers for PCR amplification. Sequence homology and similarity analysis showed that the 120-bp repeat unit family is diverse with single nucleotide changes and a few indels occurring throughout the sequence. No characteristic genome or species-specific variants have developed during the evolution of the Triticeae species. Fluorescent in situ hybridization verified that the repeat is present as large blocks at mainly subtelomeric or interstitial sites in rye and the B genome of wheat and only has a few sites in the A and D genome of wheat. In all species investigated, each of the chromosomal sites harbored many different family members. Substantial copy number differences between genomes were observed, with the family being abundant in the R and B genomes but not A and D genomes. We conclude that homogeneization events have not been operative in this repeat and that the common ancestor of the Triticeae tribe had multiple sequences of the 120-bp family with a range of variation not unlike that seen within and between species today. This diversity has been maintained when sites are moved within the genome and in all species since their split within the Triticeae.