Interactive network between nucleus and plastid

Abstract

A large number of nuclear genes are embedded into complex regulatory networks, which control the biogenesis and functions of the chloroplast at many levels. They contribute to a coordinated and adaptive expression of plastid and corresponding nuclear genes in a tissue-specific and developmentally dependent way and play a substantial role in establishing photosynthesis. They often reveal homologies to prokaryotic genes even if the pathways and the functions have not always been conserved in eukaryotes. During evolution, the plant genome was generated by post-endosymbiotic loss and gain of function, gene transfers and duplications. This extensive genome restructurations resulted in a specific co-evolution of the three genetic compartments of the plant cell. This implies as well that regulation of gene expression has been phylogenetically integrated into different signal transduction pathways. In order to develop a comprehensive concept of these evolutionary established regulatory processes we are focussing on both a genetic approach in Arabidospis thaliana by analysing mutants defective in different steps of plastid gene expression and genome-plastome incompatibility by generating new combinations of genetic compartments in different organisms (cybrids and hybrids). Several new genes have been identified by high resolution mapping and T-DNA tagging and a comprehensive analysis of these new functions will be presented.