Shift in variability of 2,4-dichlorophenoxyacetic acid-deprived pear cell suspensions

Abstract

Quiescent 2,4D-dependent pear fruit cells (Pyrus communis L.) were cultured in a bioreactor in the absence of 2,4-Dichlorophenoxyacetic acid. Effects on the ability to divide following transfer into different concentrations of auxin (0; 0.45; 2.3; 4.5; 6.8; 9 pM) are studied and discussed. Changes in cell number and in cell viability during subculture were examined (at all 2,4-D concentrations). In the presence of 2.3, 4.5 and 6.8/~M of 2,4-D, in the standard medium, pear cells undergo a classical growth cycle and cell mortality increased only after 16 days. The level of ploidy estimated by cytophotometry shows, after previous starvation, a significant shift only for 4.5 pM 2,4-D concentration, the value of the usual culture medium of the studied strain.