Ferretti Ursula, Ciura Joanna, Ksas Brigitte, Rác Marek, Sedlářová Michaela, Kruk Jerzy, Havaux Michel, Pospíšil Pavel
Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, Olomouc, 783 71, Czech Republic.
Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, 30-387, Poland.
Plant J. 2018 Jun 14. doi: 10.1111/tpj.13993.
Prenylquinols (tocochromanols and plastoquinols) serve as efficient physical and chemical quenchers of singlet oxygen ( O ) formed during high light stress in higher plants. Although quenching of O by prenylquinols has been previously studied, direct evidence for chemical quenching of O by plastoquinols and their oxidation products is limited in vivo. In the present study, the role of plastoquinol-9 (PQH -9) in chemical quenching of O was studied in Arabidopsis thaliana lines overexpressing the SOLANESYL DIPHOSPHATE SYNTHASE 1 gene (SPS1oex) involved in PQH -9 and plastochromanol-8 biosynthesis. In this work, direct evidence for chemical quenching of O by plastoquinols and their oxidation products is presented, which is obtained by microscopic techniques in vivo. Chemical quenching of O was associated with consumption of PQH -9 and formation of its various oxidized forms. Oxidation of PQH -9 by O leads to plastoquinone-9 (PQ-9), which is subsequently oxidized to hydroxyplastoquinone-9 [PQ(OH)-9]. We provide here evidence that oxidation of PQ(OH)-9 by O results in the formation of trihydroxyplastoquinone-9 [PQ(OH) -9]. It is concluded here that PQH -9 serves as an efficient O chemical quencher in Arabidopsis, and PQ(OH) -9 can be considered as a natural product of O reaction with PQ(OH)-9. The understanding of the mechanisms underlying O chemical quenching provides information on the role of plastoquinols and their oxidation products in the response of plants to photooxidative stress.
异戊二烯基喹醇（生育三烯酚和质体醌醇）是高等植物在高光胁迫期间形成的单线态氧（¹O₂）的有效物理和化学猝灭剂。尽管此前已对异戊二烯基喹醇对¹O₂的猝灭进行了研究，但质体醌醇及其氧化产物对¹O₂的化学猝灭在体内的直接证据有限。在本研究中，在过表达参与质体醌醇-9（PQH₂-9）和质体色素酚-8生物合成的法尼基二磷酸合酶1基因（SPS1oex）的拟南芥品系中，研究了PQH₂-9在¹O₂化学猝灭中的作用。在这项工作中，展示了质体醌醇及其氧化产物对¹O₂化学猝灭的直接证据，这是通过体内显微镜技术获得的。¹O₂的化学猝灭与PQH₂-9的消耗及其各种氧化形式的形成有关。¹O₂将PQH₂-9氧化生成质体醌-9（PQ-9），随后PQ-9被氧化为羟基质体醌-9 [PQ(OH)-9]。我们在此提供证据表明，¹O₂将PQ(OH)-9氧化导致生成三羟基质体醌-9 [PQ(OH)₃-9]。本文得出结论，PQH₂-9是拟南芥中一种有效的¹O₂化学猝灭剂，PQ(OH)₃-9可被视为¹O₂与PQ(OH)-9反应的天然产物。对¹O₂化学猝灭潜在机制的理解为质体醌醇及其氧化产物在植物对光氧化胁迫反应中的作用提供了信息。
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