Nuclear DNA changes during plant development and the morphogenetic response in vitro of Nicotiana tabacum tissues

Cytophotometric and biochemical analyses indicate changes with plant development in the amount and organization of the nuclear DNA in epidermal and subepidermal tissues excised from different portions of tobacco stems: DNA is progressively lost with tissue ageing, while amplification of repeated sequences occurs in tissues developed after phase change. These genome variations are related to the morphogenetic response of the tissues cultured in vitro, which differs both quantitatively and qualitatively: loss of DNA sequences progressively impairs morphogenetic capability; DNA amplification may be a factor of the explant's ability to regenerate flowers. These results point to the possible role of the nuclear DNA condition of differentiated tissues in determining their morphogenetic expression in vitro.