title: The dual role of phytoene synthase genes in carotenogenesis in carrot roots and leaves.
abstract: Carrot (Daucus carotaL.) is an important food crop and is useful for studying carotenogenesis due to the quantity and diversity of carotenoids in its roots. Phytoene synthase catalyzes the first committed step in the carotenoid biosynthesis pathway, and its overexpression is the main driving force in the orange phenotype. At present, we lack fundamental knowledge of the role of these genes and their effects on carotenoid accumulation in leaves. In the present study, three backcross inbred lines (BC2S4) with different colored roots derived from a cross between the orange inbred line (Af) and related wild species were used to investigate the role of the duplicatedDcPSYgenes in root carotenogenesis. Promoter analysis showed thatDcPSYgenes have diverged substantially in their regulatory sequences after gene duplication. Expression levels ofDcPSY1andDcPSY2were generally positively correlated with carotenoid content during root development. In mature leaves, total carotenoid content was higher than that in the roots,DcPSY1expression increased extremely higher thanDcPSY2expression compared with roots, andDcPSY1was more sensitive thanDcPSY2during leaf de-etiolation under sunlight. These results suggest thatDcPSY1seems to make an important contribution to carotenoid accumulation in the leaves and is important for photosynthesis and photoprotection, but they are not the determining factors of root color. This expands our understanding of the regulation of carotenoid biosynthesis in carrot.
authors: Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Ministry of Agriculture, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Science, No. 12 Nanda Street, Zhongguan Cun, Haidian District, Beijing, 100081 China.
authors: Hui
authors: H
authors: Wang
authors: Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Ministry of Agriculture, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Science, No. 12 Nanda Street, Zhongguan Cun, Haidian District, Beijing, 100081 China.
authors: Cheng-Gang
authors: CG
authors: Ou
authors: Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Ministry of Agriculture, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Science, No. 12 Nanda Street, Zhongguan Cun, Haidian District, Beijing, 100081 China.
authors: Fei-Yun
authors: FY
authors: Zhuang
authors: Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Ministry of Agriculture, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Science, No. 12 Nanda Street, Zhongguan Cun, Haidian District, Beijing, 100081 China.
authors: Zhen-Guo
authors: ZG
authors: Ma
keywords: Backcross inbred lines (BILs); Carotenoids accumulation; Carrot; De-etiolation; Phytoene synthase gene