Expression of the stilbene synthase genes in the needles of spruce Picea jezoensis

Abstract

Stilbenes are valuable plant phytoalexins, the biosynthesis of which is characteristic of different groups of phylogenetically unrelated plants. It is believed that all the stilbenes are the derivatives of resveratrol (3,5,4'-trihydroxy-trans-stilbene) or compounds close to it (pinosylvin or piceatannol). The last stage of the resveratrol biosynthesis takes place with the involvement of stilbene synthase or resveratrol synthase (STS). The family Pinaceae is characterized by the presence of the derivatives of pinosylvin (genus Pinus) and piceatannol (genus Picea), the biosynthetic pathways of which are scarcely examined. Previously, in different species of the genus Picea, only two stilbene synthase genes were described. On the basis of RNA isolated from the needles of spruce Picea jezoensis, the full-length cDNAs of the four stilbene synthase genes, PjSTS1a, PjSTS1b, PjSTS2, and PjSTS3, were obtained. Then, using the clone frequency analysis and real-time PCR, expression of the PjSTS1a, PjSTS1b, PjSTS2, and PjSTS3 genes was examined in the needles of P. jezoensis accessions of different age and sampled in different seasons (spring, summer, autumn, winter). Among the analyzed transcripts, the PjSTS1a and PjSTS1b genes were the most frequent, indicating their higher level of expression compared to other STS genes. The highest level of PjSTS1a and PjSTS1b expression was observed in autumn, while the level of PjSTS2 and PjSTS3 expression was the highest in spring and winter. Moreover, the highest PjSTS expression was detected in the young tissues of P. jezoensis in autumn, which may indicate a higher level of stilbene biosynthesis in these tissues.