Differential Gene Expression Induced by Cold Stress in Olea europaea L.

Molecular biology methodologies were used in order to isolate genes involved in cold-induced tolerance processes in Olea europaea cultivars. In order to systematically isolate and study the involved genes we used the PCR-based cDNA subtraction method, termed suppression subtractive hybridisation (SSH) for generation of subtracted cDNA libraries from tolerant plants, both in control and cold treated material. Samples of Olea europaea L. 'Leccino', tolerant to low temperatures, were used. The material was selected from plants survived in Tuscany after very low temperature exposition in the year 1985. The clones were cultured for two years in controlled conditions. Control samples were kept in a optimal temperature; cold stressed samples were treated with decreasing temperatures till -10 degrees C. RNAs were extracted from control and cold treated plants and used for the construction of reverse and forward cDNA libraries, that allow the identification of genes that are switched on/off after the treatments. The system has allowed the rapid identification of differentially expressed genes. Selected cDNA clones were sequenced and analyzed using the FASTA, BLASTX and BLASTN programs.