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KMID : 0903519680090010001
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Journal of the Korean Society of Agricultural Chemistry and Biotechnology
1968 Volume.9 No. 1 p.1 ~ p.7
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Action Spectra for Light - Induced De - Epoxidation and Epoxidation of Xanthophylls in Spinach Leaf
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Abstract
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The action Spectra for violaxanthin de-epoxidation and zeaxanthin expoxidation in New Zealand spinach leaf segments Tetragonia expansa, were determined at equal incident quanta of 2.0×10^(15) quanta ㎝^(-2) second^(-1). The action spectrum for de-epoxidation had major peaks at approximately 180 and 648 ㎚. Blue light was slightly more effective than red light and little activity was observed beyond 700 ㎚. The action spectrum for epoxidation showed major peaks at around 441 and 670 ㎚. Blue light was more effective than red light and light beyond 700 ㎚ showed definite activity.
The net result of de-epoxidation and epoxidation is a cyclic scheme, the violaxanthin cycle, which consumes O₂ and photoproducts. The action spectra indicate that the violaxanthin cycle is more active m clue than in red light and therefore could accout for O₂ uptake stimulated by blue light. The differences between the action spectra for de-epoxidation suggest that possibly two photosynthetic systems are involved. It was suggested that the violaxanthin cycle may functional a pathway for the consumption of excess photoproducts generated in blue light or the conversion of these photoproducts to other forms of energy.
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