Transgenic potato plants with altered expression levels of chloroplast NADP-malate dehydrogenase:: interactions between photosynthetic electron transport and malate metabolism in leaves and in isolated intact chloroplasts
Transgenic potato plants with altered expression levels of chloroplast NADP-malate dehydrogenase:: interactions between photosynthetic electron transport and malate metabolism in leaves and in isolated intact chloroplasts
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DOI：
10.1007/s004250050461
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发表时间：
1998-12-01
期刊：
影响因子：
4.3
通讯作者：
Scheibe, R
中科院分区：
文献类型：
--
作者：
Backhausen, JE;Emmerlich, A;Scheibe, R
以转基因马铃薯（Solanum tuberosum L.）为材料，研究了苹果酸阀在稳态光合作用调控中的作用。cv Desiree）植物，其质体NADP依赖性苹果酸脱氢酶（NADP-MDH; EC 1.1.1.82）的表达改变。在感官取向上。选择了总共9个稳定的正义和反义系，其具有10%或30%以及400%的野生型NADP-MDH能力。从野生型和突变体植物的叶中分离完整的叶绿体。在叶绿体中的正义转化体的酶量增加被激活，在野生型叶绿体，但草酰乙酸依赖的苹果酸形成的速率增加，只测量部分解偶联。相反，从反义转化体的叶绿体产生草酰乙酸除了后，只有很少的苹果酸。在稳态光合作用与完整叶片的测量产生气体交换参数和叶绿素荧光没有差异。NADP-MDH表达不足的叶片苹果酸含量没有变化，但在过表达的植物高两倍。NADP-MDH表达的改变明显影响铁氧还蛋白的氧化还原状态，特别是在弱光下。此外，苹果酸阀可以成功地与循环电子流竞争电子，但发生这种情况的条件是相当人为的。
The contribution of the malate valve in the regulation of steady-state photosynthesis was studied in transgenic potato (Solanum tuberosum L. cv Desiree) plants with altered expression of plastidic NADP-dependent malate dehydrogenase (NADP-MDH; EC 1.1.1.82), Mutant plants were obtained after transformation with the homologous Nmdh gene in antisense orientation, or with the Nmdh gene from pea (Pisum sativum L.) in sense orientation. A total number of nine stable sense and antisense lines with 10% or 30%, and 400% of wild-type NADP-MDH capacity were selected. Intact chloroplasts were isolated from leaves of wildtype and mutant plants. In chloroplasts from sense transformants the increased enzyme amount was activated as in wild-type chloroplasts, but increased rates of oxaloacetate-dependent malate formation were only measured upon partial uncoupling. In contrast, chloroplasts from antisense transformants produced only little malate upon oxaloacetate addition. Measurements with intact leaves during steady-state photosynthesis yielded no differences in gas-exchange parameters and chlorophyll fluorescence. The leaf malate content was unchanged in NADP-MDH underexpressors, but twice as high in overexpressing plants. The altered NADP-MDH expression clearly influences the redox state of ferredoxin, especially in low light. Furthermore, the malate valve can successfully compete for electrons with cyclic electron flow, but the conditions under which this occurs are quite artificial.