Yuan Hui, Owsiany Katherine, Sheeja T E, Zhou Xiangjun, Rodriguez Caroline, Li Yongxi, Welsch Ralf, Chayut Noam, Yang Yong, Thannhauser Theodore W, Parthasarathy Mandayam V, Xu Qiang, Deng Xiuxin, Fei Zhangjun, Schaffer Ari, Katzir Nurit, Burger Joseph, Tadmor Yaakov, Li Li
Robert W. Holley Center for Agriculture and Health, U.S. Department of Agriculture-Agricultural Research Service (H.Y., X.Z., Y.Y., T.W.T., L.L.), Plant Breeding and Genetics Section, School of Integrative Plant Science (H.Y., K.O., T.E.S., X.Z., C.R., L.L.), Plant Biology Section, School of Integrative Plant Science (M.V.P.), and Boyce Thompson Institute for Plant Research (Z.F.), Cornell University, Ithaca, New York 14853;Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., Q.X., X.D.);University of Freiburg, Faculty of Biology II, D79104 Freiburg, Germany (R.W.); andNewe Ya'ar Research Center, Agricultural Research Organization, Ramat Yishay 30095, Israel (N.C., A.S., N.K., J.B., Y.T.).
Robert W. Holley Center for Agriculture and Health, U.S. Department of Agriculture-Agricultural Research Service (H.Y., X.Z., Y.Y., T.W.T., L.L.), Plant Breeding and Genetics Section, School of Integrative Plant Science (H.Y., K.O., T.E.S., X.Z., C.R., L.L.), Plant Biology Section, School of Integrative Plant Science (M.V.P.), and Boyce Thompson Institute for Plant Research (Z.F.), Cornell University, Ithaca, New York 14853;Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., Q.X., X.D.);University of Freiburg, Faculty of Biology II, D79104 Freiburg, Germany (R.W.); andNewe Ya'ar Research Center, Agricultural Research Organization, Ramat Yishay 30095, Israel (N.C., A.S., N.K., J.B., Y.T.)
Plant Physiol. 2015 Sep;169(1):421-31. doi: 10.1104/pp.15.00971. Epub 2015 Jul 29.
Carotenoids are crucial for plant growth and human health. The finding of ORANGE (OR) protein as a pivotal regulator of carotenogenesis offers a unique opportunity to comprehensively understand the regulatory mechanisms of carotenoid accumulation and develop crops with enhanced nutritional quality. Here, we demonstrated that alteration of a single amino acid in a wild-type OR greatly enhanced its ability to promote carotenoid accumulation. Whereas overexpression of OR from Arabidopsis (Arabidopsis thaliana; AtOR) or from the agronomically important crop sorghum (Sorghum bicolor; SbOR) increased carotenoid levels up to 2-fold, expression of AtOR(His) (R90H) or SbOR(His) (R104H) variants dramatically enhanced carotenoid accumulation by up to 7-fold in the Arabidopsis calli. Moreover, we found that AtOR(Ala) (R90A) functioned similarly to AtOR(His) to promote carotenoid overproduction. Neither AtOR nor AtOR(His) greatly affected carotenogenic gene expression. AtOR(His) exhibited similar interactions with phytoene synthase (PSY) as AtOR in posttranscriptionally regulating PSY protein abundance. AtOR(His) triggered biogenesis of membranous chromoplasts in the Arabidopsis calli, which shared structures similar to chromoplasts found in the curd of the orange cauliflower (Brassica oleracea) mutant. By contrast, AtOR did not cause plastid-type changes in comparison with the controls, but produced plastids containing larger and electron-dense plastoglobuli. The unique ability of AtOR(His) in mediating chromoplast biogenesis is responsible for its induced carotenoid overproduction. Our study demonstrates OR(His/Ala) as powerful tools for carotenoid enrichment in plants, and provides insights into the mechanisms underlying OR(His)-regulated carotenoid accumulation.
类胡萝卜素对植物生长和人类健康至关重要。橙色（OR）蛋白作为类胡萝卜素合成的关键调节因子的发现，为全面了解类胡萝卜素积累的调控机制以及培育营养品质更高的作物提供了独特的机会。在此，我们证明了野生型OR中单个氨基酸的改变极大地增强了其促进类胡萝卜素积累的能力。拟南芥（Arabidopsis thaliana；AtOR）或重要农作物高粱（Sorghum bicolor；SbOR）中OR的过表达使类胡萝卜素水平提高了2倍，而AtOR(His)（R90H）或SbOR(His)（R104H）变体的表达在拟南芥愈伤组织中显著增强了类胡萝卜素积累，增幅高达7倍。此外，我们发现AtOR(Ala)（R90A）促进类胡萝卜素过量产生的功能与AtOR(His)相似。AtOR和AtOR(His)均未对类胡萝卜素合成基因的表达产生重大影响。AtOR(His)在转录后调节八氢番茄红素合酶（PSY）蛋白丰度方面与AtOR表现出相似的与PSY的相互作用。AtOR(His)引发了拟南芥愈伤组织中膜状有色体的生物发生，其结构与橙色花椰菜（Brassica oleracea）突变体花球中发现的有色体相似。相比之下，与对照相比，AtOR并未引起质体类型的变化，但产生了含有更大且电子致密质体小球的质体。AtOR(His)介导有色体生物发生的独特能力是其诱导类胡萝卜素过量产生的原因。我们的研究证明OR(His/Ala)是植物中类胡萝卜素富集的有力工具，并为OR(His)调节类胡萝卜素积累的潜在机制提供了见解。
