EFFECTS OF SUBCULTURING AND PHYSICAL CONDITION OF MEDIUM ON THE NUCLEAR BEHAVIOR OF A PLANT TISSUE CULTURE

Abstract

A callus of the common garden peony, Paeonia suffruticosa, was subcultured on solid and liquid media and analyzed intensively for a period of 153 days in order to test the effects of subculturing and the physical conditions of culture on the mitotic cycle kinetics of a population of cells, particularly in relation to the degree of heteroploidy. The parameters investigated in the kinetic studies included mitotic index values, cell generation time, and the time required for the cell population to double. The mitotic index of Paeonia cells cultured in liquid medium was found to be about two and a half times higher than for those cultured on solid; successive subculturing did not affect the mitotic index on either type of medium. The most significant results of the study came from the chromosome count data, in which diploid and tetraploid cells fluctuated in predominance in successive subcultures, and the apparent earlier manifestation of polyploidy on liquid medium. Mitotic index, cell generation, and population doubling times remained constant throughout the study.