Abstract:

【Objective】The aim of this study was to clone full-length cDNA of key enzyme gene psy for carotene biosynthesis in strawberry, to investigate its sequence characteristics and to analyze its expression in different organ.【Result】 The psy gene cDNA sequence was cloned from strawberry fruit using RT-PCR and RACE techniques, bioinformatics methods were used to analyze cDNA sequence obtained and putative amino acid sequence,Semi-quantitative PCR method were used to study the expression of psy gene in different tissues. 【Result】 The full-length cDNA of psy (GenBank accession number：FJ784889) in strawberry was cloned, The sequence consists of 1 458 bp with an intact open reading frame of l 194 bp, encoding a polypeptide of 398 amino acids. Homology analysis showed that the deduced PSY protein was highly homologous to other PSY proteins from different species. Phylogenetic analysis also indicated that PSY was more related to PSY of carrot and corn. Prokaryotic expression showed recombinant plasmid was efficiently expressed in Escherichia coli BL21. The semi-quantitative RT-PCR analysis revealed psy can be expressed in different strawberry tissues, and the expression level was differed in these tissues, the highest expression level was detected in flower, while moderate expression levels were found in fruits at the red ripening stage, fruits at the pink ripening stage, white fruits, green fruits and old leaf, the lowest level was present in new leaves. 【Conclusion】 Gene psy was firstly isolated and characterized from strawberry, which may participate in carotene biosynthesis.

Key words: strawberry, phytoene synthase, psy, gene cloning