title: Mutation of Arabidopsis HY1 causes UV-C hypersensitivity by impairing carotenoid and flavonoid biosynthesis and the down-regulation of antioxidant defence.
abstract: Previous pharmacological results confirmed that haem oxygenase-1 (HO-1) is involved in protection of cells against ultraviolet (UV)-induced oxidative damage in soybean [Glycine max (L.) Merr.] seedlings, but there remains a lack of genetic evidence. In this study, the link between Arabidopsis thaliana HO-1 (HY1) and UV-C tolerance was investigated at the genetic and molecular levels. The maximum inducible expression of HY1 in wild-type Arabidopsis was observed following UV-C irradiation. UV-C sensitivity was not observed in ho2, ho3, and ho4 single and double mutants. However, the HY1 mutant exhibited UV-C hypersensitivity, consistent with the observed decreases in chlorophyll content, and carotenoid and flavonoid metabolism, as well as the down-regulation of antioxidant defences, thereby resulting in severe oxidative damage. The addition of the carbon monoxide donor carbon monoxide-releasing molecule-2 (CORM-2), in particular, and bilirubin (BR), two catalytic by-products of HY1, partially rescued the UV-C hypersensitivity, and other responses appeared in the hy1 mutant. Transcription factors involved in the synthesis of flavonoid or UV responses were induced by UV-C, but reduced in the hy1 mutant. Overall, the findings showed that mutation of HY1 triggered UV-C hypersensitivity, by impairing carotenoid and flavonoid synthesis and antioxidant defences.
authors.affiliation: College of Life Sciences, Co. Laboratory of Nanjing Agricultural University and Carl Zeiss Far East, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Yanjie
authors.initials: Y
authors.lastname: Xie
authors.forename: Daokun
authors.initials: D
authors.lastname: Xu
authors.forename: Weiti
authors.initials: W
authors.lastname: Cui
authors.forename: Wenbiao
authors.initials: W
authors.lastname: Shen
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D053898:Biosynthetic Pathways / Q000528:radiation effects; D002338:Carotenoids / Q000096:biosynthesis*; D002734:Chlorophyll / Q000378:metabolism; D015536:Down-Regulation / Q000528:radiation effects; D005419:Flavonoids / Q000378:metabolism*; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D018384:Oxidative Stress; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants; D029681:Arabidopsis Proteins; D005419:Flavonoids; D002734:Chlorophyll; D002338:Carotenoids; D006419:Heme Oxygenase (Decyclizing)