The developmental transition to flowering represses ascorbate peroxidase activity and induces enzymatic lipid peroxidation in leaf tissue in Arabidopsis thaliana.
The developmental transition to flowering represses ascorbate peroxidase activity and induces enzymatic lipid peroxidation in leaf tissue in Arabidopsis thaliana.
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DOI：
10.1016/s0168-9452(00)00316-2
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发表时间：
2000-09
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影响因子：
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通讯作者：
Zhenzhen Ye;Roxana Rodriguez;Augustine Tran;Hoang Hoang-Hoang;Darryn de los Santos;Shawn Brown;R. Vellanoweth
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文献类型：
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作者：
Zhenzhen Ye;Roxana Rodriguez;Augustine Tran;Hoang Hoang-Hoang;Darryn de los Santos;Shawn Brown;R. Vellanoweth
许多植物物种的叶子衰老与活性氧（ROS）对细胞大分子的氧化损伤增加有关。由于已知许多植物中的活性氧水平及其损伤产物在衰老过程中会增加，因此这些变化可能是由于某些抗氧化酶水平的下降所致。通过特定的测定，我们发现向抽薹和开花的发育转变与抗坏血酸过氧化物酶活性下降多达 5 倍和叶绿体超氧化物歧化酶的增加有关。正如预期的那样，这些变化与脂质过氧化产物的测量增加有关。通过产物的HPLC分离，我们鉴定了不同的位置异构体，并发现在抽苔转变后发生立体特异性脂质过氧化。产品分布表明，通过脂氧合酶介导的酶介导的脂质过氧化是观察到的增加的原因。令人惊讶的是，虽然与已知的过氧化氢诱导抗氧化防御一致，但 APX 的活性随着进一步发育（繁殖和结籽）而反弹，并且这种增加（高达 5 倍）与脂质过氧化的下降和可见衰老症状的出现有关。因此，在拟南芥中，ROS 的增加与开花的发育过渡有关，可能是由于 APX 活性的程序性下降，并且显然导致脂氧合酶的氧化激活和随后的脂质过氧化。尽管衰老程序继续有增无减，但后期 APX 的重新激活似乎有助于降低脂质过氧化率。
Leaf senescence in many plant species is associated with increased oxidative damage to cellular macromolecules by reactive oxygen species (ROS). Since ROS levels and their damage products in many plants are known to increase during senescence, it is possible that these changes are due to a decline in the levels of certain antioxidant enzymes. Using specific assays, we find that the developmental transition to bolting and flowering is associated with up to a 5-fold decline in ascorbate peroxidase activity and an increase in chloroplastid superoxide dismutase. As expected, these changes are associated with a measured increase in lipid peroxidation products. By HPLC separation of the products, we identified the different positional isomers and find that stereospecific lipid peroxidation occurs after the bolting transition. The product distribution suggests that enzyme-mediated lipid peroxidation, via a lipoxygenase, is responsible for the observed increase. Surprisingly, though consistent with the known induction of antioxidant defenses by hydrogen peroxide, the activity of APX rebounds with further development (reproduction and seed setting) and this increase (up to 5-fold) is associated with declines in lipid peroxidation and with the onset of visible senescence symptoms. Thus, in Arabidopsis, ROS increases are associated with the developmental transition to flowering, perhaps due to programmed declines in APX activity, and apparently lead to the oxidative activation of lipoxygenase and subsequent lipid peroxidation. The reactivation of APX at later stages appears to help reduce the lipid peroxidation rate, although the senescence program continues unabated.