Isoenzyme replacement of glucose-6-phosphate dehydrogenase in the cytosol improves stress tolerance in plants
Isoenzyme replacement of glucose-6-phosphate dehydrogenase in the cytosol improves stress tolerance in plants
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DOI：
10.1073/pnas.0812902106
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发表时间：
2009-05-12
影响因子：
11.1
通讯作者：
von Schaewen, Antje
中科院分区：
文献类型：
--
作者：
Scharte, Judith;Schoen, Hardy;von Schaewen, Antje
在抗性烟草源叶中，通过抑制葡萄糖-6-磷酸脱氢酶（G6PDH）或NADPH氧化酶，可以防止烟草疫霉侵染后的氧化破裂和随后形成的超敏病变。这一观察结果表明，由于细胞质中G6PDH活性的增加，NADPH利用率的提高可能有利于植物防御。g6pdh编码基因G6PD具有高NADPH耐受性，通过胞质表达（cP2）工程改造，将其导入一个敏感品种。感染后，过表达cP2的转基因（先前易感）株系表现出早期氧化爆发、胼胝质沉积和代谢参数的变化。这些反应导致与抗性植物相似的超敏损伤及时形成，尽管其程度在不同转基因系之间差异很大。额外的RNAi抑制内源性胞质G6PD异构体导致高度均匀的防御反应，也增强了耐旱性和开花。细胞质G6PDH似乎是植物防御反应结果的关键因素；因此，代表了一个重要的目标调制的抗逆性。由于细胞质中G6PDH的同工酶替代在各种线索下都是有益的，因此我们提出这种策略作为一种增强胁迫耐受性的工具。
In source leaves of resistant tobacco, oxidative burst and subsequent formation of hypersensitive lesions after infection with Phytophthora nicotianae was prevented by inhibition of glucose-6-phosphate dehydrogenase (G6PDH) or NADPH oxidases. This observation indicated that plant defense could benefit from improved NADPH availability due to increased G6PDH activity in the cytosol. A plastidic isoform of the G6PDH-encoding gene, G6PD, displaying high NADPH tolerance was engineered for cytosolic expression (cP2), and introduced into a susceptible cultivar. After infection, transgenic (previously susceptible) lines overexpressing cP2 showed early oxidative bursts, callose deposition, and changes in metabolic parameters. These responses resulted in timely formation of hypersensitive lesions similar to resistant plants, although their extent varied considerably between different transgenic lines. Additional RNAi suppression of endogenous cytosolic G6PD isoforms resulted in highly uniform defense responses and also enhanced drought tolerance and flowering. Cytosolic G6PDH seems to be a crucial factor for the outcome of plant defense responses; thus, representing an important target for modulation of stress resistance. Because isoenzyme replacement of G6PDH in the cytosol was beneficial under various kinds of cues, we propose this strategy as a tool to enhance stress tolerance in general.