Correlation between persistent forms of zeaxanthin-dependent energy dissipation and thylakoid protein phosphorylation

Area of Science:

• Plant Physiology
• Photosynthesis Research
• Molecular Biology

Background:

• High light stress impacts plant energy dissipation and protein phosphorylation.
• The xanthophyll cycle is crucial for energy dissipation, while protein phosphorylation regulates various cellular processes.

Purpose of the Study:

• To investigate the role of protein dephosphorylation in sustained energy dissipation and photoprotection.
• To examine the correlation between thylakoid protein phosphorylation patterns and zeaxanthin retention under high light stress.

Main Methods:

• Leaf discs of *Parthenocissus quinquefolia* were treated with protein phosphatase inhibitors.
• Whole plants of *Monstera deliciosa* and spinach were exposed to high light.
• Thylakoid protein phosphorylation was assessed using anti-phosphothreonine antibody.
• Pigment content and chlorophyll fluorescence were measured.

Main Results:

• Inhibition of dephosphorylation led to zeaxanthin retention and sustained energy dissipation (NPQ).
• A correlation was found between dark-sustained D1/D2 phosphorylation, zeaxanthin retention, and photosystem II priming for energy dissipation.
• *Monstera deliciosa* exhibited more pronounced sustained phosphorylation and unusual Lhcb protein phosphorylation patterns compared to spinach.

Conclusions:

• Dark-sustained D1/D2 protein phosphorylation is associated with sustained zeaxanthin retention and energy dissipation in light-stressed leaves.
• Protein phosphorylation patterns of D1/D2 and Lhcb proteins vary among species and are linked to photoprotective mechanisms.
• These findings highlight the complex regulation of photoprotection in plants under high light stress.