Thylakoid membrane reorganization during Zantedeschia aethiopica spathe regreening: Consequence of the absence of Δ 3- trans-hexadecenoic acid in photochemical activity

Abstract

Soon after its formation the fruiting spathe of Zantedeschia aethiopica undergoes senescence which is characterized by the loss of its photosynthetic activity. During fruiting, spathe senescence is inhibited and 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 (flora 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 photophosphorylation rates. Our results indicate that, besides their ultrastructural similarity to leaf chloroplasts, regreened spathe chloroplasts showed values of photochemical and photophosphorylation rates lower than those found in leaf chloroplasts. These results are discussed in relation to the absence of the fatty acid Δ 3- trans-hexadecenoic acid from regreened spathe thylakoid membranes, and we suggest that this fatty acid could be an important factor for optimal photochemical and photophosforylation activities.