Modulated gene expression during the cold acclimation process in tolerant and sensitive clones of cultivar Leccino (Olea europaea L.)

The plants are constantly exposed to environmental changes that need to be addressed with appropriate modifications of gene expression. The genetic approach to the study of the response to biotic and abiotic stresses is of great importance in plants, for the identification of the genes involved and their activation mechanisms. In our work, we have characterized the expression of some genes induced during the acclimation under low temperatures in plants of Olea europaea L., by isolating DNA sequences differentially expressed in a cold tolerant clone of Leccino cultivar by using the suppression subtractive hybridisation (SSH). The sequences obtained were analysed by sequencing. Some sequences of the libraries and from orthologous genes expressed in various abiotic/biotic stress treatments, were labelled and used as probes for slot blot hybridization with total RNAs extracted from cold sensitive and tolerant Leccino clones treated with decreasing temperatures down to -10 °C, thus mimicking a process of cold acclimation. Six genes were found to be of interest for the adaptation to cold stress, whose expression is differentially modulated in the two clones. The most important result was in a bimodal response during the acclimation phases, the causes of which have been discussed.