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Updated: 09-12-10

DOES LUTEIN PLAY A KEY ROLE IN THE PROTECTION OF PHOTOSYNTHETIC APPARATUS IN ARABIDOPSIS UNDER SEVERE OXIDATIVE STRESS?
 

HONG-YING HUANG^{1, 2, §}, QIANG ZHANG^{1, §}, LI-PING ZHAO², JI-NAN FENG² AND CHANG-LIAN PENG¹* 

Abstract: Many environmental stresses result in increased generation of reactive oxygen species (ROS), such as superoxide (·O₂^-), hydrogen peroxide (H₂O₂), and hydroxyl radical (·OH), in plant cells. A mild or moderate stress induces a significant increase in the generation of ·O₂^- and H₂O₂ and a severe stress induces a significant increase in the generation of ·OH. The three ROS: ·O₂^-, H₂O₂ and ·OH were used to treat leaf discs of the wild type (WT), the npq1 mutant lacking zeaxanthin and the lut2 mutant lacking lutein in Arabidopsis by chlorophyll fluorescence imaging to test our previous hypothesis that lutein might play an important photoprotective role under severe stress. During the ·O₂^- and H₂O₂-treatment under light, F_v/F_m, Ф_PSII, ETR, qP and NPQ exhibited the sequence of sensitivity to ROS in the leaves of the three phenotypes: npq1 > lut2 > WT. However, during the ·OH-treatment under light, these chlorophyll parameters exhibited another different sequence: lut2 > npq1 > WT. Thus, it can be concluded that xanthophyll cycle plays a key role under mild and moderate stress but lutein plays a key role under severe stress. These results provided more experimental evidence to support our previous hypothesis.

Abbreviations: ·O₂^-– superoxide; ·OH– hydroxyl radical; ETR– apparent electron rate; F_m– maximum fluorescence yield of a dark-adapted leaf disc; F_m′– maximum fluorescence yield of a light-adapted leaf disc; F_o– minimum fluorescence yield of a dark-adapted leaf disc; F_v/F_m– maximal PSII quantum yield; H₂O₂– hydrogen peroxide; NPQ– nonphotochemical quenching; qE– △pH-dependent component of nonphotochemical quenching; qP– coefficient of photochemical quenching; ROS– reactive oxygen species; Ф_PSII– effective PSII quantum yield.

¹Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, College of Life Sciences, South China Normal University, Guangzhou 510631, China

²Department of Chemistry and Life Science, Xiangnan College, Chenzhou, Hunan 423000, China

*Corresponding author: E-mail: pengchl@scib.ac.cn; Tel: + 86-20-85217612, Fax: + 86-20-85217612,

^§ These authors contributed equally to this work

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