Résumé
We have used two complementary approaches, SSH (Suppression Subtractive Hybridization) and microarray-based expression profiling, to isolate and identify candidate genes associated to rice response under osmotic stress. Mannitol treatment (100 mM) was applied on rice plantlets under hydroponic conditions and 12 SSH libraries were constructed using mRNA isolated from osmotic-stressed and unstressed control tissues (leaf and root) harvested at 15 minutes, 1 hour, 5 hours, and 7 days after treatment. A set of 10,000 SSH cDNA clones selected among these libraries, together with other 12,000 rice cDNA clones from a progressive salt stress SSH collection, were spotted onto glass slides. The 22k microarray was hybridized with RNA from short-(pool of 15 minutes and 1 hour) and medium-term (5 hours) treatments from both roots and leaves of osmotic-stressed and unstressed plants and four hybridizations were performed for each experiment. Forty-three clones were significantly under- or overexpressed by osmotic treatment. Sequence analysis and blast search revealed that a large number of these genes are involved in root morphogenesis and development, signal transduction and ROS scavenging. Functions of these candidate genes in rice tolerance/adaptation to drought will be discussed. (Résumé d'auteur)