The Involvement of the Complexes of Photosystems in the Organization of Chloroplast Ultrastructure in Pea Mutants

Abstract

We studied the involvement of pigment-protein complexes of photosystems (PS) in the development and spatial arrangement of thylakoids in chloroplasts of pea (Pisum sativum L.) leaves. The initial line (cv. Torsdag) and its mutants, chlorotica 2004 displaying primary disturbances in the PSI reaction centers and chlorotica 2014 containing only 50% of chlorophyll and, as a sequence, the reduced amount of all pigment-protein complexes. A proportional decrease in the content of PSI and PSII complexes in the chlorotica 2014 mutant resulted in a partial reduction of the whole chloroplast membrane system, whereas grana and stroma thylakoid regions were well developed. In contrast, a loss of only 20% of chlorophyll and destruction of PSI complexes in the chlorotica 2004 mutant by 50% resulted in the destruction of stroma thylakoid regions and disturbed longitudinal thylakoid and grana orientation. It was concluded that protein-protein interactions in pigment-protein complexes played a key role in the structure of thylakoid membranes and their longitudinal orientation.