Journal
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES
Volume 355, Issue 1402, Pages 1395-1403Publisher
ROYAL SOC LONDON
DOI: 10.1098/rstb.2000.0701
Keywords
carotenoid; lutein; xanthophyll cycle; photoprotection; non-photochemical quenching (NPQ)
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There are multiple complementary and redundant mechanisms to provide protection against photo-oxidative damage, including non-photochemical quenching (NPQ). NPQ dissipates excess excitation energy as heat by using xanthophylls in combination with changes to the light-harvesting complex (LHC) antenna. The xanthophylls are oxygenated carotenoids that in addition to contributing to NPQ can quench singlet or triplet chlorophyll and are necessary for the assembly and stability of the antenna. We have genetically manipulated the expression of the epsilon -cyclase and beta -carotene hydroxylase carotenoid biosynthetic enzymes in Arabidopsis thaliana. The epsilon -cyclase overexpression confirmed that lut2 (lutein deficient) is a mutation in the epsilon -cyclase gene and demonstrated that lutein content carl be altered at the level of mRNA abundance with levels ranging from 0 to 180% of wild-type. Also, it is clear that lutein affects the induction and extent of NPQ, The deleterious effects of lutein deficiency on NPQ in Arabidopsis and Chlamydomonas are additive, no matter what the genetic background, whether npq1 (zeaxanthin deficient), aba1 or antisense beta -hydroxylase (xanthophyll cycle pool decreased). Additionally, increasing lutein content causes a marginal, but significant, increase in the rate of induction of NPQ despite a reduction in the xanthophyll cycle pool size.
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