Decline in leaf photooxidative-stress tolerance with age in tobacco
Decline in leaf photooxidative-stress tolerance with age in tobacco
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DOI：
10.1016/j.plantsci.2005.01.020
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发表时间：
2005-06
期刊：
影响因子：
5.2
通讯作者：
M. Ohe;Madhusudhan Rapolu;Takahiro Mieda;Y. Miyagawa;Y. Yabuta;K. Yoshimura;S. Shigeoka
中科院分区：
文献类型：
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作者：
M. Ohe;Madhusudhan Rapolu;Takahiro Mieda;Y. Miyagawa;Y. Yabuta;K. Yoshimura;S. Shigeoka
为了阐明叶片衰老过程中抗氧化胁迫能力下降的机制，研究了不同叶龄叶片中各种抗氧化剂和抗氧化酶水平的差异。在8周龄的烟草植株中，尽管叶绿素含量没有变化，但与年轻叶片相比，老叶中的蛋白质含量和光合能力显著降低。老叶有组成性较高的H2 O2水平。活性氧清除系统的成分分析表明，老叶抗坏血酸，谷胱甘肽和大多数抗氧化酶，特别是过氧化氢酶，铜/锌-超氧化物歧化酶，抗坏血酸过氧化物酶（APX）的水平显着降低。当不同叶龄的叶片用0.5μM甲基紫精在150μmol photons m-2s-1的中等光强下处理时，老叶损失更多的叶绿素和持续的离子泄漏。在诱导的光氧化胁迫，叶绿体APX，水-水循环的关键组成部分，特别是在老叶被破坏。这些研究结果表明，与叶片衰老相关的抗氧化剂和抗氧化酶水平的下降导致光氧化胁迫耐受性降低，这可能反过来加速衰老的传播。
To clarify the mechanism of the decline in oxidative stress tolerance of leaves during the course of senescence, we studied the differences in the levels of various antioxidants and antioxidant enzymes in leaves of different ages. In 8-week-old tobacco plants, even though the chlorophyll content had not changed, the protein content and the photosynthetic capacity were significantly decreased in the older leaves compared to the younger leaves. The older leaves had constitutively higher levels of H2O2. Analyses of the components of the active oxygen species-scavenging system revealed that older leaves had significantly lower levels of ascorbate, glutathione and most of the antioxidant enzymes, especially catalase, Cu/Zn-superoxide dismutase, and ascorbate peroxidase (APX). When leaves of different ages were treated with 0.5μM methylviologen under moderate light intensity at 150μmol photons m−2s−1, the older leaves lost more chlorophyll and sustained ion leakage. During the induced photooxidative stress, chloroplastic APX, a key component of the water–water cycle, was particularly destroyed in the older leaves. These findings suggest that the decline in the levels of antioxidants and antioxidant enzymes associated with leaf senescence lead to lower photooxidative-stress tolerance, which might in turn accelerate the propagation of senescence.