Carotenoid involvement in the regulation of Spirodela polyrhiza (L.) Schleid resistance to cold shock

Effect of short-time (15 sec, 5, 15, 30 min) cold stress (0,1-0,2°C) at 0,1 umol photons м-2 s-1 over the Spirodela polyrhiza (L.) Schleid carotenoid composition cultivated under the laboratory conditions has been studied. It is found that the sum of carotenoid pigments of Spirodela polyrhiza (L.) does not change and averages 206,9 ± 11,5 mkg/g in fresh weight. Pool increase of lutein+zeaxanthin (by 5-8%) has been observed in response to a short-time Spirodela polyrhiza cooling with simultaneous decrease of violaxanthin content (by 16%). Violaxanthin de-epoxidation occurs in the minute time spans and the depth of conversion does not depend on the cold shock duration. The data obtained indicate that pigments of the violaxanthin cycle may participate in realization of transitory emergency protection systems of photosynthetic apparatus by increasing the share of thermal energy dissipation of the absorbed light and preventing singlet oxygen formation.