Moustaka Julietta, Tanou Georgia, Adamakis Ioannis-Dimosthenis, Eleftheriou Eleftherios P, Moustakas Michael
Department of Botany, School of Biology, Aristotle University of Thessaloniki, University Campus, 54124 Thessaloniki, Greece.
Faculty of Agriculture, Forestry and Natural Environment, School of Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
Int J Mol Sci. 2015 Jun 18;16(6):13989-4006. doi: 10.3390/ijms160613989.
Exposure of Arabidopsis thaliana young and mature leaves to the herbicide paraquat (Pq) resulted in a localized increase of hydrogen peroxide (H2O2) in the leaf veins and the neighboring mesophyll cells, but this increase was not similar in the two leaf types. Increased H2O2 production was concomitant with closed reaction centers (qP). Thirty min after Pq exposure despite the induction of the photoprotective mechanism of non-photochemical quenching (NPQ) in mature leaves, H2O2 production was lower in young leaves mainly due to the higher increase activity of ascorbate peroxidase (APX). Later, 60 min after Pq exposure, the total antioxidant capacity of young leaves was not sufficient to scavenge the excess reactive oxygen species (ROS) that were formed, and thus, a higher H2O2 accumulation in young leaves occurred. The energy allocation of absorbed light in photosystem II (PSII) suggests the existence of a differential photoprotective regulatory mechanism in the two leaf types to the time-course Pq exposure accompanied by differential antioxidant protection mechanisms. It is concluded that tolerance to Pq-induced oxidative stress is related to the redox state of quinone A (QA).
将拟南芥的幼叶和成熟叶暴露于除草剂百草枯（Pq）中，会导致叶脉和相邻叶肉细胞中过氧化氢（H₂O₂）局部增加，但这种增加在两种叶型中并不相同。H₂O₂产生增加与反应中心关闭（qP）相伴。在Pq暴露30分钟后，尽管成熟叶中诱导了非光化学猝灭（NPQ）的光保护机制，但幼叶中的H₂O₂产生量较低，这主要是由于抗坏血酸过氧化物酶（APX）的活性增加幅度更大。之后，在Pq暴露60分钟后，幼叶的总抗氧化能力不足以清除形成的过量活性氧（ROS），因此，幼叶中出现了更高的H₂O₂积累。光系统II（PSII）中吸收光的能量分配表明，在两种叶型中存在针对Pq暴露时间进程的不同光保护调节机制，同时伴有不同的抗氧化保护机制。得出的结论是，对Pq诱导的氧化应激的耐受性与醌A（QA）的氧化还原状态有关。
