In silico identification and characterization of ICS (isochorismate synthase) gene and its expression in Salix purpurea L.

Plants always influenced human kind. Their importance is related not only to the presence of oxygen in atmosphere but also to their relevance as source of food, energy, medicines. They are also used in different industrial application to improve the quality of life. Among them willows (Salix spp.) regained increasing interest due to the high productivity of biomass, regeneration capacity after cutting and other wide possibilities of uses. Moreover, willows are known for producing high value secondary metabolites such as salicylate glucosides. The recent availability of the genome of Salix purpurea in computer databases offers the opportunity to understand how certain genes and their products work. Among the various metabolic pathways the one of phenylpropanoids is of particular interest. This pathway is known for its involvement in the production of lignin for biomass / bioenergy production and its cross talk with the salicylate glycosides metabolism implicated in systemic acquired resistance (SAR). Chorismate, from shikimate pathway, is the precursor for both, phenilphropanoids and phenolic glycosides, with the involvement of phenylalanine ammonia lyase (PAL) and isochorismate synthase (ICS) enzymes. PAL enzyme is the first acting in phenylpropanoids pathways. It converts chorismate-derived phenylalanine to cinnamic acid (CA). The latter leads to lignin and to salicylate glycosides. ICS converts chorismate into isochorismate which also produces salicylate glycosides. Particularly, salicylic acid (SA) is one of the diverse phenolic compounds acting as a signal molecule in various types of stresses. In Arabidopsis thaliana, this compound appears to be synthesized primarily via an isochorismate-utilizing pathway in the chloroplast. Given the importance of salycilate glycosides and the central role of ICS in the biosynthesis of these metabolites in the human context, the aim of this thesis is the identification, characterization and gene expression analysis of isochorismate syntase gene in Salix sp.