02 / 11 / 2012

Metabolism of terpenes in the response of grape (Vitis vinifera L.) leaf tissues to UV-B radiation

Por: Mariana Gil, Mariela Pontin, Federico Berli, Rubén Bottini, Patricia Piccoli. En: Elsevier Ltd. Phytochemistry 77 (2012) 89-98.

This study investigated the terpene profiles as determined by GC-EIMS analysis of in vitro cultured plants of Vitis vinifera exposed to a ‘field-like’ dose of UV-B (4.75 kJ m 2 d 1) administered at two different fluence rates (low, 16 h at 8.25 lWcm 2, and high 4 h at 33 lWcm 2). Low UV-B treatment increased levels of the membrane-related triterpenes sitosterol, stigmasterol and lupeol, more notable in young leaves, suggesting elicitation of a mechanism for grapevine acclimation. By contrast, accumulation of compounds
with antioxidant properties, diterpenes a and c tocopherol and phytol, the sesquiterpene E-nerolidol and the monoterpenes carene, a-pinene and terpinolene had maximum accumulation under high UV-B, which was accentuated in mature leaves. Also the levels of the sesquiterpenic stress-related hormone abscisic acid (ABA) increased under high UV-B, although 24 h post irradiation ABA concentrations decreased. Such increments of antioxidant terpenes along with ABA suggest elicitation of mechanism of defense. The adaptative responses induced by relatively low UV-B irradiations as suggested by synthesis of terpenes related with membrane stability correlated with augments in terpene synthase activity.

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