Effects of temperature on accumulation of starch or lipid in chloroplasts of grapevine.

The amount of starch accumulated in chloroplasts of grapevine leaves fell, with increasing temperature, from 23% of dry weight at 18/13° C (day/night) to 1% at 35/30° C, whereas total lipids in the leaf rose from 6 to 16% of dry weight. Preparations viewed by electron microscopy had large starch granules in the chloroplasts at 18/13° C, and large lipid droplets at 35/30° C. At 35/30° C chlorophyll content of chloroplasts was high and grana prominent, suggesting that the results were due to selective effects of temperature on metabolic pathways.