Hideg Eva, Majer Petra
Institute of Plant Biology, Biological Research Center, P.O. Box 521 H-6701 Szeged, Hungary.
Acta Biol Hung. 2010;61 Suppl:49-60. doi: 10.1556/ABiol.61.2010.Suppl.6.
Contributions of preventive and antioxidant (energy dissipating and singlet oxygen neutralizing) processes to tolerating high light stress (photoinhibition) were examined in green-house grown tobacco (Nicotiana tabacum) plants acclimated to high or low light conditions and also in sun and shade leaves collected from a natural grown linden tree (Tilia platyphyllos). Tobacco leaves survived a short (1 h) exposure to photoinhibition by activating non-regulated non-photochemical quenching [Y(NO)] rather than relying on photo-protective, regulated non-photochemical quenching [Y(NPQ)]. Low light acclimated leaves had lower singlet oxygen scavenging ability and activated Y(NO) to a larger extent than high light acclimated ones. Low light grown leaves also suffered singlet oxygen mediated photo-damage, while no singlet oxygen was detected in high light acclimated leaves during photoinhibition. Natural grown linden leaves, however, coped with prolonged daily exposures to high light mainly by activating regulated non-photochemical quenching Y(NPQ), although they also featured very efficient singlet oxygen neutralizing. Our results suggest that high light tolerance is achieved by preventing photoinhibition of photosystem II via efficient photo-protective energy dissipation rather than relying on quenching of stress-induced pro-oxidative agents.
在适应高光或低光条件的温室种植烟草（Nicotiana tabacum）植株以及从天然生长的菩提树（Tilia platyphyllos）采集的向阳叶和遮阴叶中，研究了预防和抗氧化（能量耗散和单线态氧中和）过程对耐受高光胁迫（光抑制）的贡献。烟草叶片通过激活非调节性非光化学猝灭[Y(NO)]而非依赖光保护的调节性非光化学猝灭[Y(NPQ)]，在短时间（1小时）的光抑制处理中存活下来。与高光适应叶片相比，低光适应叶片的单线态氧清除能力较低，且Y(NO)的激活程度更大。低光生长的叶片也遭受单线态氧介导的光损伤，而在光抑制期间高光适应叶片中未检测到单线态氧。然而，天然生长的菩提树叶片主要通过激活调节性非光化学猝灭Y(NPQ)来应对每日长时间的高光照射，尽管它们也具有非常高效的单线态氧中和能力。我们的结果表明，通过有效的光保护能量耗散来防止光系统II的光抑制，而非依赖于淬灭应激诱导的促氧化剂，从而实现高光耐受性。
