Objectif A study has been carried out to investigate whether or not invasion of rice by Agrobacterium results from its ability to overcome the static defence system of rice. Since not all the biological reactions of rice to pathogenic and nonpathogenic microorganisms are equal, it was decided to survey the physiological and molecular changes in rice against biotic and abiotic challenges, in order to find the rate limiting steps of Agrobacterial infection. First, chitosan and salicylic acid have been tested for their effects of hypersensitive (HS) response on rice suspension cells. Whereas both induced the secretion of several pathogen associated proteins such as chitinase, only chitosan induced cell necrosis. Either catalase or oxygen scavengers can greatly reduce the cell damage. This HS response was not induced by Agrobacterial inoculation. Second, a gene capable of responding to pathogen attack has been isolated and characterised. This gene, encoding a peroxidase, increased its expression dramatically after chitosan induction. The promoter has been transcriptionally fused with the coding region of uidA gene, which encodes the enzyme beta-glucuronidase. The construct has been introduced into rice explants via electroporation and into protoplasts. The transferred construct was shown to be the inducible by chitosan. Third, our study on T-deoxyribonucleic acid (T-DNA) transfer via Agrobacterium provided direct evidence that a bacterial peptide is capable of acting as a eukaryotic (plant) nuclear targeting signal. A chimeric gene has been constructed by fusing the virD2 gene, which is located on the virulence region to Ti plasmid of A. tumefaciens and was responsible for the formation of T-strands, and the Escherichia coli lacZ gene. Cell fractionation and electron microscopy (EM) studies with transgenic tobacco plants containing the virD2-lacZ fusion protein indicate that the first 292 amino acids of virD2 are able to direct the cytoplasmic protein beta-galactosidase to the plant nucleus. Programme(s) IC-ISC C - Activity (Euratom, EEC) on cooperation in science and technology, 1984- Thème(s) Data not available Appel à propositions Data not available Régime de financement CSC - Cost-sharing contracts Coordinateur GENT UNIVERSITY Contribution de l’UE Aucune donnée Adresse Sint Pietersnieuwstraat 25 9000 GENT Belgique Voir sur la carte Coût total Aucune donnée
