Wang Hui, Ou Cheng-Gang, Zhuang Fei-Yun, Ma Zhen-Guo
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.
Mol Breed. 2014;34(4):2065-2079. doi: 10.1007/s11032-014-0163-7.
Carrot ( L.) 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 duplicated genes in root carotenogenesis. Promoter analysis showed that genes have diverged substantially in their regulatory sequences after gene duplication. Expression levels of and were generally positively correlated with carotenoid content during root development. In mature leaves, total carotenoid content was higher than that in the roots, expression increased extremely higher than expression compared with roots, and was more sensitive than during leaf de-etiolation under sunlight. These results suggest that seems 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.
胡萝卜（L.）是一种重要的粮食作物，由于其根部类胡萝卜素的数量和多样性，对研究类胡萝卜素生成很有帮助。八氢番茄红素合酶催化类胡萝卜素生物合成途径中的第一个关键步骤，其过表达是橙色表型的主要驱动力。目前，我们对这些基因的作用及其对叶片中类胡萝卜素积累的影响缺乏基础知识。在本研究中，利用橙色自交系（Af）与相关野生种杂交产生的三个具有不同颜色根部的回交自交系（BC2S4）来研究重复基因在根部类胡萝卜素生成中的作用。启动子分析表明，基因复制后，这些基因的调控序列发生了很大分化。在根部发育过程中，和的表达水平通常与类胡萝卜素含量呈正相关。在成熟叶片中，总类胡萝卜素含量高于根部，与根部相比，表达增加的幅度远高于表达，并且在阳光下叶片脱黄化过程中比更敏感。这些结果表明，似乎对叶片中的类胡萝卜素积累做出了重要贡献，对光合作用和光保护很重要，但它们不是根部颜色的决定因素。这扩展了我们对胡萝卜中类胡萝卜素生物合成调控的理解。
