Inhibitory Effects of p-Hydroxybenzyl Alcohol on Somatic Embryogenesis in Carrot Cell Cultures.

Abstract

Somatic embryogenesis in carrot (Daucus carooa L.) is strongly inhibited by certain factors that accumulate in the medium of cultures with high embryogenic carrot cell density. We previously identified p -hydroxybenzyl alcohol as one of these inhibitory factors. In this study, we performed a detailed analysis of the effects of p -hydroxybenzyl alcohol on somatic embryogenesis. p -Hydroxybenzyl alcohol strongly inhibited the formation of somatic embryos by suppressing cell division. The inhibitory effect on the development of globular embryos was stronger than that on the development of heart-shaped and torpedo -shaped embryos. In contrast, p -hydroxybenzyl alcohol had no effect on the proliferation of both undifferentiated embryogenic cells or non-embryogenic cells. These results indicate that p -hydroxybenzyl alcohol inhibits the division of cells in a way that is specific to the early stage of somatic embryogenesis and that plays an important role in the formation of somatic embryos.

4‐Hydroxybenzyl alcohol accumulates in suspension‐cell cultures and inhibits somatic embryogenesis in carrot

“…1). We previously showed that exogenous application of authentic 4HBA at 1.0×10 −7 M strongly inhibits somatic embryogenesis and the inhibitory effect of 4HBA is strong on the development of early globular embryos (Kobayashi et al 2000b). Therefore, the rapid accumulation of 4HBA in high cell density cultures during the early stages might cause the strong suppression of somatic embryogenesis.…”

“…3). On the other hand, the inhibitory effect of 4HBA was strong during the development of early globular embryos (Kobayashi et al 2000b). The early globular stages of somatic embryogenesis are important for differentiation and pattern formation in somatic embryos (Fujimura and Komamine 1980; Dudits et al 1991).…”

“…We previously identified one of the inhibitory endogenous factors as 4‐hydroxybenzyl alcohol (4HBA) (Kobayashi et al 2000a). Authentic 4HBA strongly inhibits somatic embryogenesis by suppressing only the rapid division of cells that is specific to the early globular stage of development (Kobayashi et al 2000b). This inhibitory effect of 4HBA is different from that of the natural and chemically synthesized factors that specifically suppress the transition from the heart‐shaped stage to the torpedo‐shaped stage of somatic embryogenesis (LoSchiavo et al 1986; Baldan et al 1995; Capitano et al 1997; Toonen et al 1997).…”

Development of the embryo proper and the suspensor during plant embryogenesis

“…An inhibitory factor isolated from the medium was firstly characterized as a 4-hydroxybenzyl alcohol (4HBA; Kobayashi et al 2000a). 4HBA accumulated rapidly in the medium and specifically inhibits rapid cell division during the early globular stage of somatic embryogenesis (Kobayashi et al 1999b(Kobayashi et al , 2000b(Kobayashi et al , 2001. While 4HBA inhibits embryogenesis in carrot, this factor does not inhibit somatic embryogenesis in several other species including Japanese larch (data not shown).…”