Function and evolution of plastid sigma factors

Chloroplasts are plant-specific organelles that perform photosynthesis and responsible for the world's primary productively. Using light energy, chloroplasts produce many important products, including starch, amino acids, lipids, pigments and various secondary products. Therefore, chloroplasts are essential to the lives of all plants and animals alike. Chloroplast transformation is a unique technology to produce huge amount of valuable materials in chloroplasts using photosynthetic energy. In order to control chloroplasts at will, we need more information on molecular basis of chloroplast gene expression and communication between the chloroplast and nucleus. Chloroplast sigma factors are key regulators of the chloroplast gene expression and chloroplast differentiation. This review summarized recent findings on roles of chloroplast sigma factors in the chloroplast differentiation and environmental responses.