INFLUENCE OF ENVIRONMENTAL-FACTORS AND AIR COMPOSITION ON THE EMISSION OF ALPHA-PINENE FROM QUERCUS-ILEX LEAVES

We studied the emission of alpha-pinene from Quercos ilex leaves. Only the abaxial side of the hypostomatous Q. ilex leaf emits alpha-pinene . Light induced photosynthesis and alpha-pinene emission. However, the response of photosynthesis to dark-to-light transitions was faster th an that of alpha-pinene, suggesting that ATP controls the emission. Th e emission was higher at 30 than at 20 degrees C, whereas photosynthes is did not change. Therefore, the relationship between photosynthesis and alpha-pinene emission does not always hold. When CO2 was removed f rom the air, transpiration was stimulated but photosynthesis and alpha -pinene emission were inhibited. alpha-Pinene inhibition was more rapi d under low O-2. When CO2 in the air was increased, photosynthesis was stimulated and transpiration was reduced, but alpha-pinene emission w as unaffected. Therefore, the emission depends on the availability of photosynthetic carbon, is not saturated at ambient CO2, and is not dep endent on stomatal opening. The pattern of alpha-pinene emission from Q. ilex is different from that of plants having specialized structures for storage and emission of terpenes. We suggest that alpha-pinene em itted by Q. ilex leaves is synthesized in the chloroplasts and shares the same biochemical pathway with isoprene emitted by isoprene-emittin g oak species.