Abstract
In order to study the mechanism of light adaptation, we determined the chloroplast pigment composition and photosynthetic properties of Begonia semperflorens plants cultivated under16 h light/8h dark photoperiod, and either low light (LL) or high light (HL) conditions. Regarding the composition of photosynthetic pigments, even though an increase of xanthophylls cycle pigments was observed, both LL and HL plants had very low Chla/Chlb ratio value, 0.6 and 1.2, respectively. Based on these results, we analyzed the pigment-protein complex composition of the thylakoids by non-denaturating electrophoresis, and found that the Photosystem I band was very weak. We were almost unable to detect the PsaA even when thylakoidal proteins were analyzed by SDS-PAGE. On the other hand, the Photosystem II protein level of Begonia was comparable with those from other plants such as tobacco similar to that other plants, which suggest that the Photosystem I/Photosystem II ratio is lower in B. semperflorens.
