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

Abstract

Somatic embryogenesis in carrot (Daucus carota L.) is strongly inhibited by certain factors that accumulate in culture medium of high-density cultures of embryogenic cells. We previously identified 4-hydroxybenzyl alcohol (4HBA) as one of the inhibitory factors. In this study, we analyzed the accumulation pattern of 4HBA in the cultures of carrot suspension cells. When somatic embryogenesis was induced by culturing embryogenic cells in phytohormone-free Murashige and Skoog medium at various initial cell densities, 4HBA accumulated in the culture medium. The concentration of 4HBA in high cell density cultures was higher than in low cell density cultures. The accumulation of 4HBA in high cell density cultures was rapid during the early days of culture. This rapid accumulation of 4HBA in high cell density cultures might result in the strong inhibition of somatic embryogenesis. The production of 4HBA decreased as the somatic embryos developed. In addition, embryogenic cells released larger amount of 4HBA into the culture medium compared with non-embryogenic cells. These results suggest that the production of 4HBA is both related to embryogenic competence and developmentally regulated during somatic embryogenesis.

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).…”