Isolation, characterization and expression of pal gene family in artichoke

For a long time, artichoke has been used in traditional medicine as a specific liver and gallbladder remedy, kidney insufficiency, and to control high cholesterol levels. In fact, artichoke extracts are rich in phenolic compounds which possess numerous biological properties as largely reported in the literature. The biosynthesis of these compounds is complex and partially shared with the synthesis of structural components such as lignin. Phenylalanine ammonia-lyase (PAL) is the enzyme involved in the first step of the phenilpropanoid biosynthesis pathway, catalyzing the deamination of phenylalanine. In most plants, this enzyme is usually coded by more than one gene. Starting from sequences present in the databases, primers were designed to amplify artichoke DNA fragments by using a PCR technology. These fragments were cloned and ten clones per sample were sequenced. Partial nucleotide sequences showed a high similarity with pal genes from other species, and were used as molecular probes for southern analysis and to screen a genomic library in order to isolate the artichoke pal gene family. At present, three members of the pal family have been isolated and characterised. The isolated genes differ for exon sequence and for intron sequence and length. First combinations specific for the different members of the isolated pal genes were used in Real Time PCR performed on cDNA from various artichoke organs. Results seem to indicate that the different members of the pal family may be differentially expressed in the different organs of the plant, similarly to other gene systems.