title: Rice carotenoid β-ring hydroxylase CYP97A4 is involved in lutein biosynthesis.
abstract: Lutein is the most abundant plant carotenoid and plays essential roles in photosystem assembly and stabilization, as well as protection against photostress. To date, only a few lutein biosynthesis genes have been identified in crop plants. In this study, the rice Cyt P450 gene CYP97A4 encoding a carotenoid β-ring hydroxylase was shown to be involved in lutein biosynthesis. The results revealed that CYP97A4 was preferentially expressed in leaf compared with spikelet, sheath, stalk and root, and encoded a protein localized at the subcellular level to the chloroplasts. Compared with the wild type, the three allelic mutants of CYP97A4 displayed lutein reductions of 12-24% with substantially increased α-carotene, while Chl a/b levels were unaltered. The increased α-carotene in the mutants led to greater sensitivity under high light stress. Similarly, reactive oxygen species (ROS) imaging of leaves treated with intense light showed that the mutants generally accumulated greater levels of ROS compared with wild-type plants, which probably caused detrimental effects to the plant photosystem. In conclusion, this study demonstrated the important role of CYP97A4 in α-carotene hydroxylation in rice, and knock-out of the gene reduced lutein and increased α-carotene, contributing to sensitivity to intense light.
authors.affiliation: National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, PR China.
authors.forename: Ming-Zhu
authors.initials: MZ
authors.lastname: Lv
authors.forename: Dai-Yin
authors.initials: DY
authors.lastname: Chao
authors.forename: Jun-Xiang
authors.initials: JX
authors.lastname: Shan
authors.forename: Mei-Zhen
authors.initials: MZ
authors.lastname: Zhu
authors.forename: Min
authors.initials: M
authors.lastname: Shi
authors.forename: Ji-Ping
authors.initials: JP
authors.lastname: Gao
authors.forename: Hong-Xuan
authors.initials: HX
authors.lastname: Lin
mesh_terms: D000595:Amino Acid Sequence; D002338:Carotenoids / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D017343:Genes, Plant; D006900:Hydroxylation; D007425:Intracellular Membranes / Q000378:metabolism; D008027:Light; D014975:Lutein / Q000096:biosynthesis* / Q000235:genetics; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D010788:Photosynthesis; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000528:radiation effects; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D011523:Protoplasts / Q000166:cytology / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D016415:Sequence Alignment; D013312:Stress, Physiological; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D017382:Reactive Oxygen Species; D002338:Carotenoids; C041635:alpha-carotene; D003577:Cytochrome P-450 Enzyme System; D014975:Lutein