CHS INTRON 1 AS A MARKER OF VARIABILITY IN OLEA EUROPAEA

Chalcone synthase (CHS) is the first enzyme of the flavonoid metabolic pathway. Comparison of chs genes sequences from different plant species reveals that the chs genes are structurally conserved and most of them contain one intron and two exons. CHS is encoded by a small multigene family in many plants. Until now, many chs genes have been cloned from monocot, dicot and some gymnosperm species; in Olea europaea two different genes have been recently identified. In this work the intron 1 of chs genes was amplified in a selected number of Italian olive cultivars with different geographic origin and in the feral form Olea europaea var. sylvestris. PCR amplifications carried out with the universal primers pair chsIntronFW/chsIntronREV (Strand et al., 1997 Mol Ecol., 6:113-118), produced a series of fragments that were cloned and sequenced. Sequence analysis showed different alleles of chs A gene; in particular we were able to found two different groups of alleles characterized by an high level of polymorphism between them. Alleles of Olea europaea var. sylvestris belong to one of these groups that we named Sylvestris like. Sequence identity between the groups of alleles found in cultivated varieties and alleles found in the wild form was around 79%. It is worth noting the appearance in the sylvestris- like group alleles of a microsatellite poly-T with high degree of polymorphism. The presence of the alleles belonging to sylvestris-like group in some cultivars suggested a possible hybridization between cultivated and wild forms.