In higher plants,etioplast,which is characterized by prolamellar bodies(PLBs),is a specific phase of plastids ready for turning into chloroplast upon illumination.The coordination of the metabolism of carotenoids and chlorophylls and the development of membrane structures is critical for etioplast development.Although ORANGE(OR) has been demonstrated to regulate carotenoid accumulation and PLB development,the molecular mechanism of OR action remains largely unclear.