Chloroplasts are essential for plant photosynthesis and growth. Many genes have been identified that regulate plant chloroplast development. However, it is not known at a molecular level how these genes regulate chloroplast biogenesis. In this study, we isolated a mutant ygl2 (yellow-green leaf2) that exhibited a pigment-defective phenotype. YGL2 encodes a geranylgeranyl reductase, and in mutant ygl2, there was a single base change (T1361G) located in the third exon of YGL2 that resulted in a missense mutation (L454R) in the encoded product. Transmission electron microscopy revealed that chloroplast development was impaired in the ygl2 mutant. The expression levels of plastid-encoded genes were significantly altered in the ygl2 mutant. Furthermore, in a yeast two-hybrid assay, we found that YGL2 interacted with the RNA editing factor MORF8.