Polymer-supported electrofusion of barley protoplasts: A synergistic effect

Abstract

The well-known phenomenon of electrofusion of plant protoplasts and animal cells can be modified by low concentrations of charged and uncharged polymers in quite different ways. The results reported here show the synergistic effect on the electrofusion of barley protoplasts by the addition of different molar masses of dextran ( M m = 5000, 10000, 500000). The concentrations are in the range between 10 μg ml −1 and 20 mg ml −1. In order to obtain optimum conditions, the following parameters were tested under microscopic observation: the rate of fusion process, the physiological state of cells, the osmolarity of the solution, and the concentration of dextran and polyanions (dextran sulfate and blue dextran). The highest fusion yield (up to 35% above the control) was achieved with dextran 5000 (0.05 mg ml −1). Stronger enhancement of electrofusion yields was found with neutral polymers of lower M m (the reproducible data shown by polyethylene glycol (PEG)). An explanation for the synergism is proposed on the basis of an adsorption isotherm, a hydrophobic interaction and the surface energy of a hydrophilic pore. The combined method of electrofusion and chemical fusion using lower polymer concentrations (two or four orders of magnitude lower than the PEG concentration for general experiments in chemical and genetic applications without an electric field) provides an advantage for obtaining a high fusion yield and for minimizing side-effects on cell viability at the same time.