Genetic dissection of chloroplast biogenesis and development: an overview.

The chloroplast is essential for photosynthesis and the production of hormones and metabolites. As a consequence, its biogenesis and development needs to be coordinated with seedling growth to ensure optimal rates of photosynthesis without oxidative damage upon seedling emergence. Studies into the processes of biogenesis and development of chloroplasts have shown how important chloroplast development during germination is for plant vitality, seed set, and growth. Indeed, even if chloroplast development is only impaired in cotyledons (the embryonic leaves of germinating seedlings) with normal chloroplast development in true leaves, plant growth and yield can be negatively impacted. Thus, it is necessary to understand the regulation and mechanism of chloroplast development. This reviewwill concentrate on how chloroplasts differentiate, giving emphasis to current insights on the different steps of chloroplast development as well as into regulatory factors and molecular requirements for chloroplast biogenesis and development gained from genetic and mutagenic studies. Given the breadth of the topic, we are restricted to citing examples of recent articles and reviews, with a strong emphasis on Arabidopsis (Arabidopsis thaliana), because the majority of the genetics studies have been performed on this model plant.