Multiple Interactions between Media, Growth Factors and the Environment of Carrot Cultures: Effects on Growth and Morphogenesis

Abstract

Carrot explants appropriately nourished and stimulated proliferate and yield cells which produce plantlets in great abundance; the cells so cultivated are, in fact, totipotent. In this respect, and as they give rise to embryoids, the cultured cells behave like zygotes. Significantly, certain stimuli that induce the growth of initially quiescent carrot cells are drawn from the environment of immature embryos, i.e., the liquid endosperm of coconut (cocos), an extract of immature grains of corn (Zea) or the fluid from the vesiculate embryo sac of fruits of horsechestnut (Aesculus). It is from such sources that evidence of balanced and partial growth promoting systems and of interactions between their component parts has been drawn. The superiority of the naturally balanced fluids over their defined, but still incomplete, experimental replacements has been stressed (Steward and Degani, 1969). In fact, in a variety of ways, the effectiveness of the environment of the ovule, which may bring one cell that can grow to maturity as an embryo plantlet, has to be recognized. This effectiveness is attributable to a combination of circumstances, of which the interactions here described are but a part. Since carrot cells may give rise to small proembryonic cell clusters that undergo embryogenesis, evidence accumulated that the course of their development could be modulated by controllable properties of the environment (Steward et al., 1970).