Rice mutant resources for deciphering developmental and adaptive processes

Paralleling the international program of sequencing of the rice genome which culminated with the publication of the 390 Mbp chromosome sequence end of 2004, considerable efforts have been undertaken in this model cereal for generating insertion libraries, characterizing flanking sequences of inserts and gathering phenotype and sequence information in web-accessible databases. Several independent national initiatives in Korea, China, France and Taiwan launched in the late 1990s have led to the generation of more than 460,000 T -DNA insertion lines and the release of more than 113,000 Flanking Sequence Tags (FSTs) in public databases. It is presumed that the full characterization of all these lines with other concurrent initiatives using the maize Ac/Ds and En/Spm transposable elements and the tissue culture stimulated endogenous retrotransposon Tosl7 will enable rice geneticists to find at least one insertion in any rice gene and several alleles in most of the genes. To contribute to the international effort of production of sequence-indexed insertion libraries in rice, we have generated a collection of 30,000 Nipponbare lines which are characterized by 25,000 and 15,000 flanking sequence tags of T-DNA and Tos17 insert respectively. These lines are being field evaluated and seed increased in.CIAT, Colombia and the phenotypes documented,in the Oryza Tag Line database at http://urgi.versailles.inra.fr/OryzaTagLine/. This work was conducted in the frame of the national genomics initiative Génoplante (http://genoplante.com) and also supported by the National Sequencing Centre, Génoscope. In France, several research groups are now using these resources to decipher the molecular control of grain filling processes, response to biotic and abiotic stresses and of plant architecture determinants. Our group has focused its research on root development and plasticity in response to osmotie stress. Aside forward genetic screens which have yielded tagged mutants currently under analysis, a medium scale reverse genetics screen was conducted in the frame of projects supported by the Generation Challenge Program and the European Union. This screen included genes identified through expression profiling in osmotic- and salt stressed tissues (SSH microarrays) or orthologs of Arabidopsis developmental and stress-related genes, and also a long term, overall investigation of the role of the rice Leucine-rich repeat receptor like kinase (LRR RLK) (320 genes), CLV3 like (30 WOX (15 genes) genes in development and biotic/abiotic stress response. (Texte intégral)