Ksas Brigitte, Becuwe Noëlle, Chevalier Anne, Havaux Michel
CEA, IBEB, Laboratoire d'Ecophysiologie Moléculaire des Plantes, F-13108 Saint-Paul-lez-Durance, France.
CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, F-13108 Saint-Paul-lez-Durance, France.
Sci Rep. 2015 Jun 3;5:10919. doi: 10.1038/srep10919.
Plastoquinone-9 is known as a photosynthetic electron carrier to which has also been attributed a role in the regulation of gene expression and enzyme activities via its redox state. Here, we show that it acts also as an antioxidant in plant leaves, playing a central photoprotective role. When Arabidopsis plants were suddenly exposed to excess light energy, a rapid consumption of plastoquinone-9 occurred, followed by a progressive increase in concentration during the acclimation phase. By overexpressing the plastoquinone-9 biosynthesis gene SPS1 (solanesyl diphosphate synthase 1) in Arabidopsis, we succeeded in generating plants that specifically accumulate plastoquinone-9 and its derivative plastochromanol-8. The SPS1-overexpressing lines were much more resistant to photooxidative stress than the wild type, showing marked decreases in leaf bleaching, lipid peroxidation and PSII photoinhibition under excess light. Comparison of the SPS1 overexpressors with other prenyl quinone mutants indicated that the enhanced phototolerance of the former plants is directly related to their increased capacities for plastoquinone-9 biosynthesis.
质体醌-9是一种光合电子载体，其氧化还原状态在基因表达调控和酶活性调节中也发挥着作用。在此，我们表明它在植物叶片中还作为一种抗氧化剂，发挥着核心的光保护作用。当拟南芥植株突然暴露于过量光能时，质体醌-9会迅速消耗，随后在适应阶段其浓度逐渐增加。通过在拟南芥中过表达质体醌-9生物合成基因SPS1（茄尼基二磷酸合酶1），我们成功培育出了特异性积累质体醌-9及其衍生物质体色素醇-8的植株。与野生型相比，过表达SPS1的株系对光氧化胁迫具有更强的抗性，在过量光照下叶片漂白、脂质过氧化和PSII光抑制均显著降低。将过表达SPS1的植株与其他异戊二烯醌突变体进行比较表明，前者植株增强的光耐受性与其增加的质体醌-9生物合成能力直接相关。
