Abstract
It is generally believed that plastid evolved from the endosymbiosis of a unicellular photosynthetic bacterium into an ancient eukaryotic cell. In the present-day plastid genome encodes fewer than 100 ORFs, and most genes that were encoded by the bacterial ancestor have been moved to host nuclear genome. Therefore, the nucleus controls most aspects of plastid gene expression. On the other hand, it has been known that plastid send signals to the nucleus to control nuclear gene expression. However, little is known about the signaling components that regulate the expression of nuclear genes. To elucidate the signaling pathway from plastid to the nucleus, we took advantage of a mutant defective in the major protein import receptor. In this mutant, ppi2, the expression of nuclear genes encoding plastid proteins is compromised. We performed detailed expression analysis using ppi2 mutant. We show that a specific pathway was affected in the ppi2 mutant.
