Maintenance of High Photosynthetic Rates in Mesophyll Cells Isolated from Papaver somniferum

The establishment and maintenance of high rates of photosynthetic CO(2) incorporation in mesophyll cells of Papaver somniferum (opium poppy) depend on a regime of dark and light periods immediately following isolation, as well as carefully adjusted conditions of isolation. Analysis of the incorporation pattern of (14)CO(2) by the isolated cells indicates an initial "stress-response" period of approximately 20 hours characterized by increased respiratory-type metabolism and diminished photosynthesis. Under the favorable regime, this period is followed by rapid recovery and the reinstatement of a metabolic state strikingly similar to that of intact leaves in which the initial rate of CO(2) incorporation is between 110 and 175 mumoles CO(2) fixed per mg chlorophyll per hour. The photosynthetic viability of these cells can be maintained for up to 80 hours.