期刊
JOURNAL OF EXPERIMENTAL BOTANY
卷 69, 期 20, 页码 4921-4933出版社
OXFORD UNIV PRESS
DOI: 10.1093/jxb/ery242
关键词
Isoprenoids; MEP pathway; UV-B damage; violaxanthin; xanthophylls; zeaxanthin
资金
- Argentina FONCyT [PICT 2016-141, 2015-157]
- MINECO [BIO2015-71703-REDT, BIO2014-59092-P]
- AGAUR [2014SGR-1434]
- EMBO Short-Term Fellowship
Plastidial isoprenoids, such as carotenoids and tocopherols, are important anti-oxidant metabolites synthesized in plastids from precursors generated by the methylerythritol 4-phosphate (MEP) pathway. In this study, we found that irradiation of Arabidopsis thaliana plants with UV-B caused a strong increase in the accumulation of the photoprotective xanthophyll zeaxanthin but also resulted in slightly higher levels of gamma-tocopherol. Plants deficient in the MEP enzymes 1-deoxy-D-xylulose 5-phosphate synthase and 1-hydroxy-2-methyl-2-butenyl 4-diphosphate synthase showed a general reduction in both carotenoids and tocopherols and this was associated with increased DNA damage and decreased photosynthesis after exposure to UV-B. Genetic blockage of tocopherol biosynthesis did not affect DNA damage accumulation. In contrast, lut2 mutants that accumulate beta,beta-xanthophylls showed decreased DNA damage when irradiated with UV-B. Analysis of aba2 mutants showed that UV-B protection was not mediated by ABA (a hormone derived from beta,beta-xanthophylls). Plants accumulating beta,beta-xanthophylls also showed decreased oxidative damage and increased expression of DNA-repair enzymes, suggesting that this may be a mechanism for these plants to decrease DNA damage. In addition, in vitro experiments also provided evidence that pft-xanthophylls can directly protect against DNA damage by absorbing radiation. Together, our results suggest that xanthophyll-cycle carotenoids that protect against excess illumination may also contribute to protection against UV-B.
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