Studies on the recovery of crown gall tumor cells

Abstract

While a persistent but potentially reversible suppression of the tumorous state appears to be a characteristic feature of the vegetative phase of teratoma shoot growth in the crown gall disease [caused by Agrobacterium tumefaciens] of plants, a recovery from that state occurs during the reproductive phase. An analysis was made of the reproductive process in an attempt to define the precise stage at which recovery occurs. Diploid somatic cells of teratoma-derived flower parts [of Nicotiana tabacum] such as those found in petals and filaments are inherently neoplastic. Haploid cells of plants grown from anthers of the same flowers and diploid cells of F1 generation plants grown from teratoma-derived seed have recovered from the tumorous state. The loss of neoplastic properties occurs in crown gall teratoma cells during meiosis rather than during fertilization or later stages of the reproductive process. An analysis of more than 2000 teratoma-derived tumor shoots showed that a recovery from the tumorous state may also occur, although apparently as a very rare event, during the vegetative phase of teratoma shoot growth.