THYLAKOID MEMBRANE REORGANIZATION DURING ZANTEDESCHIA-AETHIOPICA SPATHE REGREENING - CONSEQUENCE OF THE ABSENCE OF DELTA(3)-TRANS-HEXADECENOIC ACID IN PHOTOCHEMICAL ACTIVITY

Soon after its formation the fruiting spathe of Zantedeschia aethiopic a undergoes senescence which is characterized by the loss of its photo synthetic activity. During fruiting, spathe senescence is inhibited an d regreening takes place. The amyloplasts present in the white spathe turn to functional chloroplasts and the spathe acquires photosynthetic capacity. In this work, thylakoid membranes were isolated from three distinct stages of spathe development (floral bud, white and regreened spathes)and used for the study of pigment-protein complexes, as well as for the determination of PSI and PSII activities and photophosphory lation rates. Our results indicate that, besides their ultrastructural similarity to leaf chloroplasts, regreened spathe chloroplasts showed values of photochemical and photophosphorylation rates lower than tho se found in leaf chloroplasts. These results are discussed in relation to the absence of the fatty acid Delta(3)-trans-hexadecenoic acid fro m regreened spathe thylakoid membranes, and we suggest that this fatty acid could be an important factor for optimal photochemical and photo phosforylation activities. (C) 1998 Elsevier Science Ltd, All rights r eserved.