Résumé
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 inserts 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 osmotic 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 genes) and WOX (15 genes) genes in development and biotic/abiotic stress response. Due to the recent establishment and characterization of large libraries of insertion lines in rice, 961 insertions (i.e. 3.8 per gene) have been identified for 255 (70%) of the LRR-RLK genes in the FST databases (http://OryGenesDB.círad.fr). 102 lines from international collections have been tested by Southern using a gene specific probe and a rearranged fragment was observed in 81 lines. Once homozygous plants were identified, their progeny was screened along with the WT sibling progeny for alteration in development and abiotic stress tolerance (PEG 20% and NaCl 150 mM). Putative homozygous-lethal lines have also been identified. So far 24 lines with homozygous progenies have been phenotyped and 4 exhibited a phenotype linked with the FST in the gene under investigation. A T-DNA insertion in a leucine-rich repeat receptor protein kinase ortholog to the EXS precursor, known as MSP1 in rice, conducts to panicle sterility. Another T-DNA insertion in a BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1 precursor exhibited extra long rachis branches. A third T -DNA insertion, in a receptor-like protein kinase precursor, exhibited shorter culms and thinner panicle rachis branches. Last, a CL3 like putative ligand of a LRR-RLK, exhibited enhanced leaf and root growths. These phenotypes are being characterized in detail. We could anticipate that this satisfactory frequency of phenotypes (17%) could be increased in testing the behaviour of the lines under other stresses, such as pathogen infection. (Texte intégral)