Photosynthetic apparatus in Selaginella. II. Changes in plastid ultrastructure and pigment content under different light and temperature regimes

Abstract

The ultrastructural details of the chloroplasts of Selaginella are identical with those of higher vascular plants. During bleaching there is an "unstacking" of grana, but the integrity of the grana and connecting fretwork is maintained. Osmiophilic droplets, containing a red pigment identified as rhodoxanthin, increase during chromoplast formation. The other carotenoids and chlorophyll decrease during bleaching. Once plastids contain swollen grana, regreening is not possible. The results of this paper and the preceding one are combined to present a hypothetical scheme of events in the bleaching–regreening process in Selaginella.