Plastid Ribosome Biogenesis During the Early Steps of Chloroplast Differentiation
Chloroplast differentiation is accomplished in several steps. In embryonic and meristematic cells, proplastids are present, characterised by their small size and the absence of internal membranes. They contain a low copy number of plastid DNA and few plastid ribosomes. Then, plastid differentiation follows several ways depending on plant organs or tissues. Because of its importance for photosynthesis, differentiation of proplastids into chloroplasts has been studied in details. It involves the co-ordinated expression of the nuclear genome and of the plastid genome. In the course of differentiation two main steps can be distinguished: firstly an early step during which the complexes necessary for plastid gene expression are synthesised and secondly, the formation of the photosynthetic apparatus. We will focus the present study on the expression of nuclear genes encoding plastid ribosomal proteins (r-proteins) that are important for early plastid differentiation.
KeywordsRibosomal Protein Nuclear Gene Ribosomal Protein Gene Plastid Gene Expression Chloroplast Differentiation
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