Effet stimulant de la poly-D-lysine sur l'entrée en mitose de cellules G2 du méristème racinaire d'Allium sativum

Abstract

Cell proliferation in Allium sativum L. primary root meristems is stimulated by poly-D-lysine. This effect has been studied on asynchronous and on hydroxyurea-synchronized meristems using cell kinetics techniques and DNA microdensitometry. The rapid increase of mitotic indices is the result of the onset of mitosis in 4C cells which are arrested in G2. However, neither the initiation of DNA synthesis in G1 cells, nor the labelling index of roots continuously incubated with tritiated thymidine, are altered. Thus, poly-D-lysine has a selective effect on G2 cells, triggering the onset of mitosis in those cells. Our results, which show that mitosis can be induced in G2 cells by an exogenous supply of a polycationic compound, are discussed in relation to the occurrence and the features of G2-arrested cells within root meristems.