Cloning of lea cDNA fragment of carrot (Daucus carota L.) and analysis of its expression features

Addition of concentrated sucrose to MS culture arrests the development of c arrot somatic embryo at the stage of cotyledon embryo and, with the sucrose concentration restored to normal level, the embryo thus arrested is reacti vated into post-embryonic development. Using the method of RT-PCR, the cDNA fragment of a new member of the Dc3 family of lea has been obtained from c arrot somatic embryo under regulated state. As revealed by Northern blottin g, strong expression has been observed in carrot somatic embryo under regul ated state but the expression was much reduced 12 h after deregulation, and nearly disappeared 24 h after. Based on this finding as well as results of related studies, it is surmised that changing the sucrose concentration in culture enabled carrot somatic embryo under suspension culture to undergo a specific course of development which is comparable to the dormancy-germin ation process of seeds.