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The multi-protein complex photosystem II (PS II) harvests photons and transfers their energy through its bound pigments to its reaction center, and ultimately to photosystem I (PSI) through the electron transport chain. The pigments responsible for caputirng the light energy in photosystems include chlorophyll a, chlorophyll b, and carotenoids.
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Quantitative Analysis of Dietary Vitamin A Metabolites in Murine Ocular and Non-Ocular Tissues Using High-Performance Liquid Chromatography

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Tocopherol functions in photosynthetic organisms.

Hiroshi Maeda¹, Dean DellaPenna

¹Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA.

Current Opinion in Plant Biology

|April 17, 2007

Summary

Tocopherols (vitamin E) are vital for plant defense during germination and seed dormancy. Surprisingly, tocopherol deficiency mainly impacts phloem loading in mature leaves under cold conditions, not light stress.

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Published on: March 21, 2016

Area of Science:

Plant biochemistry
Photosynthetic organism physiology
Molecular genetics

Background:

Genes for tocopherol (vitamin E) synthesis in plants and cyanobacteria are identified.
Mutants with disrupted tocopherol synthesis pathways offer insights into vitamin E functions.
Tocopherols are crucial antioxidants, preventing lipid peroxidation during seed and seedling stages.

Purpose of the Study:

To investigate the specific roles of tocopherols in plant physiology, particularly under stress conditions.
To understand the consequences of tocopherol deficiency in mature plant leaves.
To elucidate the function of tocopherols in plant adaptation to environmental factors like cold and light stress.

Main Methods:

Generation and analysis of plant mutants deficient in tocopherol synthesis.
Assessment of tocopherol levels and their impact on lipid peroxidation markers (malondialdehyde, phytoprostanes).
Evaluation of plant defense responses and physiological adaptations under various abiotic stresses (e.g., high light, cold).

Main Results:

Tocopherol deficiency leads to increased lipid peroxidation and inappropriate defense responses during seed dormancy and germination.
Mature leaves of tocopherol-deficient mutants show limited negative effects under most abiotic stresses, including high light.
Cell wall development in phloem transfer cells is severely impaired in tocopherol-deficient mutants under cold conditions.

Conclusions:

Tocopherols play a critical role in protecting against oxidative damage during early plant development.
Tocopherol deficiency has specific, rather than general, impacts on mature plant physiology under stress.
Tocopherols are essential for the proper adaptation of phloem loading to low temperatures, highlighting a specific role in cold stress response.