Abstract
Somatic embryos of Japanese larch (Larix leptolepis GORDON) consist of cytoplasmic dense embryo-proper and vacuolated suspensor. Somatic embryogenesis was strongly inhibited in high-cell-density cultures. The inhibition was caused by factor(s) that were released by the cells into the culture medium. In this study, we purified and identified one of the inhibitory factors found in the medium of high-cell-density cultures of larch cells. The inhibitory factor showing the strongest inhibitory activity was purified by dialysis, fractionation with ethylacetate, chromatography on an octadecylsilyl silica gel-column and HPLC. The inhibitory factor was identified as vanilline benzyl ether (VBE) by mass spectrometry and 1H- and 13C-NMR spectroscopy. VBE synthesized from vanilline and benzylchloride by Williamson synthesis. The authentic VBE inhibited somatic embryo formation in Japanese larch, especially the development of suspensor. These results suggest that VBE accumulates in high-cell-density cultures and inhibits somatic embryogenesis in Japanese larch.
