Stilbene Content and Expression of Stilbene Synthase Genes in Korean Pine Pinus koraiensis Siebold & Zucc

Abstract

Stilbenes are a large group of plant phenolic compounds that have a wide range of biologically active properties, such as antioxidant, immunomodulatory, anti-inflammatory, and anti-angiogenic effects. In plants, stilbenes are involved in the defense against environmental stresses, including fungal infections and insect attacks. The biosynthesis of stilbenes is well described for those plant species where resveratrol and its derivatives are the predominant stilbenes. However, there is little information on stilbene biosynthesis in the Pinaceae family, although the highest content of stilbenes was found in plants of this family. In this study, seasonal variations in stilbene compositions and contents in different parts of Pinus koraiensis was described (needles, bark, wood, young branches, and strobiles). HPLC-ESI-MS analysis showed the presence of seven stilbenes in P. koraiensis: t-astringin; t-piceid; cis-piceid; t-isorapontin; t-pinostilbenoside; t-resveratrol; and t-pinostilbene. Glycosylated and methylated forms of stilbenes, such as t-astringin, t-piceid, and t-pinostilbenoside, prevailed over other stilbenoids. The highest content of stilbenes was detected in the bark collected in spring and winter (up to 54.8 mg/g dry weight). The complete protein-coding sequences of three stilbene synthase genes, PkSTS1, PkSTS2, and PkSTS3, were obtained from the RNA isolated from the P. koraiensis needles. The expression of the PkSTS1, PkSTS2, and PkSTS3 genes was analyzed using real-time PCR and frequency analysis of cloned RT-PCR products in the needles of P. koraiensis collected in different seasons. Thus, we first analyzed stilbene biosynthesis in the different organs of pine P. koraiensis and PkSTS expression depending on the year seasons.