Paraquat 유도 산화스트레스하의 배추 잎에서 Ascorbate-Glutathione 회로 효소의 활성도에 대한 산화질소 (Nitric oxide)의 효과

초록

Pretreatment of chinese cabbage leaves with 100 μM sodium nitroprusside (SNP), a nitric oxide (NO) donor,effectively improved their tolerance to subsequent 2 μMparaquat (PQ)-induced oxidative damage. The fresh weight,and chlorophyll and protein contents in primary leavestreated with PQ alone were noticeably reduced over 24 hlight incubation. However, these leaf injury symptoms weresignificantly alleviated with 100 μM SNP pretreatment for 3h prior to PQ exposure. In additions, the increase of thecontents of malondialdehyde (MDA) and H2O2 due to PQexposure were significantly inhibited by SNP pretreatment. Together with the protective effects of SNP against PQtoxicity in leaves, the changes of ascorbate-glutathione cycleenzymes activities were examined. In the PQ alone treatment,the activities of APX, DHAR, and GR after 6 h incubationwere rapidly reduced and showed 19%, 50% and 39%respectively, compared with those of the control. However,the decreases in these enzyme activities were significantlyinhibited by SNP pretreatment. As a result, their activitieswere higher than those of PQ alone treatment by 5 times, 2times, and 1.5 times, respectively, at 6 h incubation. Thereafter,these enzymes decrease their activities gradually showinghigh levels than those of PQ alone. Based on the aboveresults, it can be assumed that the activation of ascorbateglutathionecycle by SNP pretreatment in chinese cabbageleaves exposed to PQ can prevent H2O2 accumulation, therebyleading to protection against PQ-induced oxidative stress. Also, these results indicate that NO acts as an protectantagainst PQ stress in the leaves of chinese cabbage.

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