Changes in the polyamine content of plastidal membranes in light- and dark-grown wildtype and pigment mutants of the unicellular green alga Scenedesmus obliquus and their possible role in chloroplast photodevelopment

Polyamines are involved in a great variety of developmental processes in plant cells, however, in many cases the mechanism and the place of action are unknown. In the present paper attempts are made to elucidate, in part, the physiological role of putrescine, spermidine, spermine and norspermidine in chloroplast development. It is shown that cultures of the unicellular green alga Scenedesmus obliquus and its pigment mutants C-2A' and C-6D, grown heterotrophically in darkness, exhibit, when exposed to light, an immediate and continuing decrease of the intracellular putrescine lever, whereas the polyamines spermidine, spermine and norspermidine present only slight changes. Additionally, a considerable redistribution of the bound polyamines in the isolated plastid membranes from various chloroplast developmental stages is observed. The fluctuation of the bound polyamines in the plastid membranes during darkness and illumination was determined and correlated to different ways of chloroplast development represented by the three types of Scenedesmus cultures (wildtype, mutants C-2A' and C-6D). A possible role of polyamines in the assembly of the various photosynthetic complexes during the formation of the photosynthetic apparatus is discussed.