Low-light-induced violaxanthin de-epoxidation in shortly preheated leaves: uncoupling from Delta pH-dependent nonphotochemical quenching.
Plants protect themselves against excessive light by the induction of Delta pH-dependent nonphotochemical quenching (qE) that is associated with de-epoxidation of violaxanthin (V) to zeaxanthin (Z) in thylakoid membranes. In this work, we report that low light (12 micromol photons m(-2) s(-1)) is sufficient for a marked stimulation of the V to Z conversion in shortly preheated wheat leaves (5 min, 40 degrees C), but without a substantial increase in qE. Re-irradiation of these leaves with high light led to a rapid induction of nonphotochemical quenching, implying a potential photoprotective role of low-light-induced Z in preheated leaves. On the contrary to low light conditions, preheated leaves exposed to high light behaved similar to nonheated leaves with respect to the V to Z conversion and qE induction. The obtained results indicate that low-light-induced lumen acidification in preheated leaves is high enough to activate V de-epoxidation, but not sufficiently high to induce the formation of quenching centers.
Ilík
Petr
P
Laboratory of Biophysics, Faculty of Science, Palacký University, Olomouc, Czech Republic. ilik@prfnw.upol.cz
Kotabová
Eva
E
Spundová
Martina
M
Novák
Ondrej
O
Kana
Radek
R
Strzałka
Kazimierz
K
D004852:Epoxy Compounds; D006358:Hot Temperature; D045342:Light-Harvesting Protein Complexes; D055668:Photochemical Processes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects*; D018521:Plant Physiological Phenomena / Q000528:radiation effects*; D036226:Seedlings; D020524:Thylakoids / Q000378:metabolism; D014908:Triticum; D024341:Xanthophylls / Q000096:biosynthesis / Q000378:metabolism / Q000528:radiation effects; D065146:Zeaxanthins
D004852:Epoxy Compounds; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D024341:Xanthophylls; D065146:Zeaxanthins; C005613:violaxanthin