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 Quercus 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 than that of [alpha]-pinene, suggesting that ATP controls the emission. The emission was higher at 30 than at 20[deg]C, whereas photosynthesis did not change. Therefore, the relationship between photosynthesis and [alpha]-pinene emission does not always hold. When CO2 was removed from the air, transpiration was stimulated but photosynthesis and [alpha]-pinene emission were inhibited. [alpha]-Pinene inhibition was more rapid under low O2. When CO2 in the air was increased, photosynthesis was stimulated and transpiration was reduced, but [alpha]-pinene emission was unaffected. Therefore, the emission depends on the availability of photosynthetic carbon, is not saturated at ambient CO2, and is not dependent 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 emitted by Q. ilex leaves is synthesized in the chloroplasts and shares the same biochemical pathway with isoprene emitted by isoprene-emitting oak species.
Loreto
F.
F
Consiglio Nazionale delle Ricerche-Istituto di Biochimica ed Ecofisiologia Vegetali (F.L., D.T.) and Consiglio Nazionale delle Ricerche-Istituto per I'Inquinamento Atmosferico (P.C., A.C., E.B., M.F.), Via Salaria, Km 29,300-00016 Monterotondo Scalo, Rome, Italy.
Ciccioli
P.
P
Cecinato
A.
A
Brancaleoni
E.
E
Frattoni
M.
M
Tricoli
D.
D