High light‐induced hydrogen peroxide production in Chlamydomonas reinhardtii is increased by high CO2 availability. (March 2015)

• Record Type: Journal Article
• Authors: Roach, Thomas; Na, Chae Sun; Krieger‐Liszkay, Anja
• Is Part Of: Plant journal. Volume 81:Number 5(2015:Mar.)
• Page Start: 759
• Page End: 766
• Publication Date: 2015-03
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12768
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12768-abs-0001"> <title>Summary</title> <p>The production of reactive oxygen species (ROS) is an unavoidable part of photosynthesis. Stress that accompanies high light levels and low CO<sub>2</sub> availability putatively includes enhanced ROS production in the so‐called Mehler reaction. Such conditions are thought to encourage O<sub>2</sub> to become an electron acceptor at photosystem I, producing the ROS superoxide anion radical (<inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj1xqn4pp" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:09607412:media:tpj12768:tpj12768-math-0001" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn><mml:mrow><mml:mo>·</mml:mo><mml:mo>−</mml:mo></mml:mrow></mml:msubsup></mml:math></alternatives></inline-formula>) and hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>). In contrast, here it is shown in <italic>Chlamydomonas reinhardtii</italic> that CO<sub>2</sub> depletion under high light levels lowered cellular H<sub>2</sub>O<sub>2</sub> production, and that elevated CO<sub>2</sub> levels increased H<sub>2</sub>O<sub>2</sub> production. Using various photosynthetic and mitochondrial mutants of <italic>C. reinhardtii</italic>, the chloroplast was identified as the main source of elevated H<sub>2</sub>O<sub>2</sub> production under high CO<sub>2</sub> availability. High light levels under low CO<sub>2</sub> availability induced photoprotective mechanisms called non‐photochemical quenching, or NPQ, including state transitions (qT) and high energy state quenching (qE). The qE‐deficient mutant <italic>npq4</italic> produced more H<sub>2</sub>O<sub>2</sub> than wild‐type cells under high light levels, although less so under high CO<sub>2</sub> availability, whereas it demonstrated equal or greater enzymatic H<sub>2</sub>O<sub>2</sub>‐degrading capacity. The qT‐deficient mutant <italic>stt7‐9</italic> produced the same H<sub>2</sub>O<sub>2</sub> as wild‐type cells under high CO<sub>2</sub> availability. Physiological levels of H<sub>2</sub>O<sub>2</sub> were able to hinder qT and the induction of state 2, providing an explanation for why under high light levels and high CO<sub>2</sub> availability wild‐type cells behaved like <italic>stt7‐9</italic> cells stuck in state 1.</p> </abstract>