Dehydroascorbate reductase affects leaf growth, development, and function
Dehydroascorbate reductase affects leaf growth, development, and function
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DOI：
10.1104/pp.106.085506
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发表时间：
2006-10-01
期刊：
影响因子：
7.4
通讯作者：
Gallie, Daniel R.
中科院分区：
文献类型：
--
作者：
Chen, Zhong;Gallie, Daniel R.
抗坏血酸（Asc）是植物中一种主要的抗氧化剂，具有解毒活性氧（ROS）和维持光合功能的作用。脱氢抗坏血酸还原酶（DHAR）的表达，负责从氧化状态再生Asc，调节细胞Asc氧化还原状态，进而影响细胞对环境ROS的反应性和耐受性。由于DHAR在Asc循环中的作用，我们研究了DHAR对植物生长是否重要。DHAR表达的抑制导致叶绿素a的优先损失，Rubisco （RbcL）大亚基量测量的Rubisco稳态降低，CO2同化速率降低。结果，观察到叶片膨胀速度减慢和叶片干重减少。此外，成熟叶片中叶绿素、RbcL、光收集复合物II和光合功能的丧失速度加快，导致叶片早衰。以株高和叶数衡量的生长速率降低与dhara介导的光合功能降低一致。增加DHAR表达可维持较高水平的叶绿素、RbcL、光收集复合物II和光合功能，导致叶片老化延迟。DHAR表达对叶片衰老的影响与脂质过氧化水平呈负相关，表明DHAR对ros介导的损伤有保护作用。这些观察结果支持这样的结论，即DHAR通过其Asc循环功能，影响叶片发育过程中叶片ROS水平和光合活性，从而影响植物生长和叶片老化的速度。
Ascorbic acid (Asc) is a major antioxidant in plants that detoxifies reactive oxygen species (ROS) and maintains photosynthetic function. Expression of dehydroascorbate reductase (DHAR), responsible for regenerating Asc from an oxidized state, regulates the cellular Asc redox state, which in turn affects cell responsiveness and tolerance to environmental ROS. Because of its role in Asc recycling, we examined whether DHAR is important for plant growth. Suppression of DHAR expression resulted in a preferential loss of chlorophyll a, a lower steady state of Rubisco as measured by the amount of the large subunit of Rubisco (RbcL), and a lower rate of CO2 assimilation. As a consequence, a slower rate of leaf expansion and reduced foliar dry weight were observed. In addition, an accelerated rate of loss of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning was observed in mature leaves, resulting in premature leaf aging. Reduced growth rate as measured by plant height and leaf number was consistent with the DHAR-mediated reduction of photosynthetic function. Increasing DHAR expression maintained higher levels of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning, resulting in delayed leaf aging. The effect of DHAR expression on leaf aging inversely correlated with the level of lipid peroxidation, indicating that DHAR functions to protect against ROS-mediated damage. These observations support the conclusion that through its Asc recycling function, DHAR affects the level of foliar ROS and photosynthetic activity during leaf development and as a consequence, influences the rate of plant growth and leaf aging.