Lipid synthesis in callus and protoplasts during culture: Analysis of dividing protoplasts of Petunia hybrida and non‐dividing protoplasts of Parthenocissus tricuspidata

Abstract

The purpose of the investigation was to study the process, by which protoplasts derived from callus tissue overcome the hydrolysis of membrane phospholipids, which is induced by the isolation. Dividing protoplasts from Petunia hybrida L. (line SFla) and non‐dividing protoplasts from Parthenocissus tricurpidara L. crown gall (Morel strain) were fed with sodium [1‐14C]‐acetate for 1 h. The incorporation was carried out at protoplast isolation and after 1, 2, 4 and 7 days of culture. The rates of fatty acid and lipid synthesis were then followed. Isolation stress induced diversions in the utilization of the precursor via triacylglycerol (Petuunia) or diacylglycerol (Partheno‐cissus) and a decrease in the synthesis of oleic acid (Parrhenocissus). During the first 2 days of culture, the rate of phospholipid synthesis was similar in both systems. Later on, an increase in the rate and in the efficiency of phospholipid synthesis was observed in dividing Petunia protoplasts. The accelerated rate of lipid synthesis allowed them to recover the same partitioning and content in membrane phospholipids as the reference cells in the callus. This process seemed to bc related to cell division, since it was not observed in the non‐dividing protoplasts of Parthenocissus.