Functional leucine-rich repeat receptor-like kinase proteins in rice : [P296]

Leucine-Rich Repeat Receptor-Like Kinases (LRR-RLKs) are plant-specific receptor kinases involved in development and defense. Taking advantage of the whole rice genome sequence, we performed an extensive sequence analysis of the 320 LRR-RLK sequences that we retrieved from the Oryza sativa sp. japonica genome database at The Institute for Genomic Research (TIGR). Our aim is to study LRR-RLKs involved in root rice development. A search in expressed genes databases shows that ~77% of these genes are potentially expressed in rice. This high percentage of expression might reflect the fact that we looked for sequences with putative functionally active domains, like the presence of cystein pairs, LRRs and kinase domains. Based on the alignment of kinase domains and phylogenetic analysis, these LRRRLKs sequences can be classified into 22 subgroups. Interestingly, the ~100 extra genes present in the rice genome compared to the Arabidopsis one belong to one single subgroup, LRR XII, whose known members are receptors involved in resistance/defense against bacteria. We find that these genes are distributed throughout the twelve rice chromosomes and that 45% of the genes are organized into 41 tandem clusters of 2 to 14 genes. Interestingly, 38.2% of LRR-RLKs belonging to subgroup LRR XII are localized on chromosome 11 with 89.7% of them organized in 5 clusters of 3 to 14 genes. Our results on the genomic organization of the LRR-RLKs also show that ~3. (Résumé d'auteur