Analyses for the mode of action of the effect of 4-hydroxybenzyl alcohol, an inhibitor of carrot somatic embryo formation, and its related compounds on somatic embryogenesis in carrot

Abstract

Carrot embryogenic cells (EC) release 4-hydroxybenzyl alcohol (4HBA), an inhibitory factor of somatic embryogenesis in carrot. Thus, high cell density culture of EC causes to failure of somatic embryo formation by 4HBA released from EC. In order to know how 4HBA acts as the inhibitor of somatic embryogenesis in carrot, 2,4-dichloroacetic acid-treated hypocotyl explants were placed on the solidified medium containing 4HBA or its related compounds and somatic embryogenesis was examined. Although 4HBA did not show inhibitory effects of somatic embryogenesis and its related compound vanillyl alcohol (VA) showed stimulatory effect. Histological and molecular biological analyses suggested that 4HBA and VA have an inhibitory effect on the early process of somatic embryogenesis, but stimulatory effect on the late process. The mode of action of the inhibitory and stimulatory effects of 4HBA and VA on somatic embryogenesis in carrot will be discussed.