Objective
Plant end symbioses with mycorrhizal fungi and nitrogen- fixing nodule bacteria play a crucial role in the cycle of phosphorus and nitrogen in most agricultural ecosystems. Arabidopsis thaliana is unable establish root endosyrnbioses. Medicago truncatula has been chosen as a model legumeio study the symbiotic genetic programmes of plants and facilitate the genetics and breeding of important legume crops such as pea, faba bean, alfalfa and clover. We propose a functional genomics project to identify most of the plant genes whose expression is modified in the course of symbiotic and pathogenic interactions, as well as other genes of agricultural importance which cannot be easily studied with A. thaliana. Structural genomics will provide genetic and physical maps to establish the distribution of important genes on the genome and facilitate their cloning. Comparative genomics will provide methods to transfer information gained from M. truncatula to legume crops.
The major results are the following: GENOME STRUCTURE OF M. TRUNCATULA Genetic mapping- Construction of a population of 195 Recombinant Inbred Lines to facilitate genetic mapping- Identification of a set of EST-derived microsatellites that have the advantages of corresponding to expressed genes and being extremely polymorphic. They can be used for characterisation of genetic diversity of Mt populations, Mt mapping and comparative mapping - High resolution genetic maps of the eight linkage groups of M. truncatula with more than 500 markers Molecular cytogenetics - Pachytene-FISH cytogenetic/physical maps of the eight chromosomes with ~80 markers.
Comparison between genetic and cytogenetic/physical maps - Molecular cytogenetic analysis of the Mt genome defining euchromatic (gene-rich) and heterochromatic (rich in repetitive sequences) regions - Cytogenetic markers to discriminate the eight Mt chromosomes Physical mapping - Construction and organisation of a Mt BAC library of 32.000 clones containing EcoRI inserts (~120 kb) - Construction and organisation of a Mt BAC library of 3.000 clones containing HindIII large inserts (~170 kb) - Detailed physical maps (BAC contigs) of three symbiotic regions of interest carrying LYK3, NORK and DMI3 genes controlling Nod factor perception and transduction FUNCTIONAL GENOMICS OF M. TRUNCATULA Large scale identification of genes involved in symbiotic interactions and pod formation and filling has been performed by transcriptomic approaches: complementing existing EST libraries by SSH cDNA libraries, preparing macro-and microarrays, and making transcriptome analyses - SSH cDNA libraries for early and late stage interactions in Mt mycorrhiza - Appressoria-elicited genes at early stage of Mt mycorrhiza - Set of genes for late stage interactions in Mt mycorrhiza - Sequence data of approx. 2.700 ESTs from two cDNA libraries of flowers and seeds/pods of Mt - High density cDNA arrays representing approx. 6.500 Mt genes - Gene expression pattern in forming seeds - Identification by transcriptome analyses of extensive sets of genes activated during rhizobial symbiosis - Establishment of Mt as a model system to study interactions of grain legumes with the root pathogenic fungus Aphanomyces euteiches - Establishment of Mt as a model system to study biocontrol by arbuscular mycorrhizal fungi against root and leaf pathogenes - Twenty Mt genes specifically linked to salt stress tolerance - Identification of a Mt gene marker for salt stress tolerance (high capacity for recovery from salt stress) Gene tagging - 1484 transgenic lines of Mt tagged with promoter-trap T-DNA - generation of an enhancer-trap vector system for the identification of specific gene expression patterns, and the misexpression of genes in a tissue-specific and developmentally regulated context - 600 enhancer-trap lines of Mt - Mt mutants altered in general development (flower development, dwarf, paranoid, Fix plants) - 213 transgenic lines of Mt with the Tnt1 retrotransposon Positional cloning - Map-based cloning and characterisation of the gene DMI3 controlling early steps of nodulation and mycorrhization, and Nod factor signal transduction COMPARATIVE GENOMICS - Alignment of the genetic maps of Medicago truncatula and Medicago sativa (lucerne) with more than 180 gene-specific markers - Genetic mapping of Mt anchor markers in Pisum sativum (pea) - Genetic map of pea and lucerne aligned by 147 points of reference with common markers - Genetic map position of 14 pea symbiotic mutations - Map-based cloning of the Nodulation Receptor Kinase (NORK) of lucerne, pea and Mt, by making use of conserved microsynteny between Mt and lucerne - Identification of LysM domain receptor kinases regulating rhizobial Nod factor-induced infection, by making use of conserved microsynteny between Mt and pea BIOINFORMATICS - Software support for semi-automatic DNA sequence analysis and annotation (BioMake), including the relational database management system (RDMS) for data entry and retrieval - Software support for microarray data and for clustering and analyses for expression profiles (EMMA), including the internet-based front-end for on-line analysis. - Web site for interrogation of the Project databases.
Fields of science (EuroSciVoc)
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques.
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques.
- natural sciencesbiological sciencesmicrobiologymycology
- natural sciencesbiological sciencesbiological behavioural sciencesethologybiological interactions
- natural sciencesbiological sciencesgeneticschromosomes
- natural sciencesbiological sciencesgeneticsgenomes
- natural sciencescomputer and information sciencesdatabasesrelational databases
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