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Báo cáo khoa học: Phytoene synthase genes in tomato (Solanum lycopersicum L.) – new data on the structures, the deduced amino acid sequences and the expression patterns

The fruit of tomato (Solanum lycopersicumL.) is a berry: red, fleshy and rich in seeds. Its colour is due to the high content of lycopene whose syn-thesis is activated by the phytoene synthase 1 (PSY1) enzyme, encoded by Psy1which is distinct fromPsy2. | ỊFEBS Journal Phytoene synthase genes in tomato Solanum lycopersicum L. - new data on the structures the deduced amino acid sequences and the expression patterns Giovanni Giorio Adriana Lucia Stigliani and Caterina D Ambrosio Metapontum Agrobios Metaponto Italy Keywords carotenoid metabolism chloroplast chromoplast fruit colour phytoene synthase Correspondence G. Giorio Metapontum Agrobios SS Jonica Km 448.2 Metaponto MT 75010 Italy Fax 39 0835 740204 Tel 39 0835 740276 E-mail ggiorio@agrobios.it All authors contributed equally to this work Received 22 October 2007 revised 27 November 2007 accepted 3 December 2007 doi 10.1111 j.1742-4658.2007.06219.x The fruit of tomato Solanum lycopersicum L. is a berry red fleshy and rich in seeds. Its colour is due to the high content of lycopene whose synthesis is activated by the phytoene synthase 1 PSY1 enzyme encoded by Psyl which is distinct from Psy2. In the present study we report on the genomic structures of the Psyl and Psy2 genes and on their transcription patterns in different tomato tissues. Our results have completely clarified the structure of the Psyl and Psy2 genes in the coding sequence region. The two genes were shown to have an highly conserved structure with seven exons being almost identical and six introns being much more variable. For Psyl and Psy2 respectively the sequenced regions were 4527 and 3542 bp long the coding sequences were 1239 bp and 1317 bp long whereas the predicted protein sequences were 412 and 438 amino acids. The two proteins are almost identical in the central region whereas most differences are present in the N-terminus and C-terminus. Quantitative real time PCR analysis showed that Psy2 transcript was present in all tested plant tissues whereas Psyl transcript could be detected in chromoplastcontaining tissues particularly in fruit where it activates and boosts lycopene accumulation. Interestingly the organ with the highest relative content of Psy2 transcript is the petal and not the