Cytogenetic features of prior dedifferentiation in lily of the valley (Convallaria majalis L.) tissue culture.

摘要

Using squashed acetocarmine preparations, the variability of the lily-of-the-valley genome in tissue culture, beginning from the explant to the eighth subcultivation, was analysed. Buds growing above ground were used as explants. Donor plants were of the karyotype 2n = 38 = 2(12m + 6sm + 1sast). Even in early culture, aberrant anaphases (17%) and aneuploid metaphases were recorded. However, by the time of the eighth passage, the tissue remained mainly diploid. The proportion of diploid cells was 68%. The karyotype structure of the intact plant in diploid cells was rather stable, despite certain rearrangements in particular chromosome pairs. Aneuploid cells in lily-of-the-valley culture were characterized by considerable genome abnormalities. The most common mechanism leading to variation in chromosome number in vitro involves chromosome breaks at the centromere, which are rare events in lily-of-the-valley cells in vivo. It has been suggested that the preservation of the genome of the intact plantby defined culture conditions is necessary for stabilization of the cardenolide-producing cell line.