In the frame of the ForEST project, cDNA libraries have been prepared from roots with or without mycorrhiza, from leaves and from wood of trees submitted to a mild water stress. From these libraries, Genoscope has produced 5' sequencing of 55,000 ESTs, i.e. presently 11,000 EST from leaves and more than 2,000 EST from wood. The insert size varies between 0,4 to 1,8kb. This project complement "Lignome" a previous project where more than 10,000 poplar EST were determined and it will be completed by the sequencing of more than 500 full length cDNA from poplar wood in the near future. The relative distribution of the different Sequences among the different cDNA libraries together with global expression analyses using Affymetrix whole poplar genome DNA chips will help to identify candidate genes important for tree adaptation to abiotic stress. Investigations will help to define:

• their precise localisation in wood using immunochemical methods,
• their function using genetic engineering
• and allelic variability in poplar natural populations.