Mild Reductions in Mitochondrial NAD- Dependent Isocitrate Dehydrogenase Activity Result in Altered Nitrate Assimilation and Piqmentation But Do Not Impact Growth  

作　　者：Agata Sienkiewicz-Porzucek Ronan Sulpice Sonia Osorio Ina Krahnert Andrea Leisse Ewa Urbanczyk-Wochniak Michael Hodges Alisdair R. Fernie Adriano Nunes-Nesi 

机构地区：[1]Max-Planck-lnstitut for Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany [2]Institute de Biotechnologie des Plantes, Unite Mixte de Recherche 8618, Centre National de la Recherche Scientifique, Universite de Paris-Sud 11, 91405Orsay Cedex, France

出　　处：《Molecular Plant》2010年第1期156-173,共18页分子植物（英文版）

摘　　要：Transgenic tomato （Solanum lycopersicum） plants were generated expressing a fragment of the mitochon- drial NAD-dependent isocitrate dehydrogenase gene （SIIDH1） in the antisense orientation. The transgenic plants displayed a mild reduction in the activity of the target enzyme in the leaves but essentially no visible alteration in growth from the wild-type. Fruit size and yield were, however, reduced. These plants were characterized by relatively few changes in pho- tosynthetic parameters, but they displayed a minor decrease in maximum photosynthetic efficiency （Fv/Fm）. Furthermore, a clear reduction in flux through the tricarboxylic acid （TCA） cycle was observed in the transformants. Additionally, bio- chemical analyses revealed that the transgenic lines exhibited considerably altered metabolism, being characterized by slight decreases in the levels of amino acids, intermediates of the TCA cycle, photosynthetic pigments, starch, and NAD（P）H levels, but increased levels of nitrate and protein. Results from these studies show that even small changes in mitochon- drial NAD-dependent isocitrate dehydrogenase activity lead to noticeable alterations in nitrate assimilation and suggest the presence of different strategies by which metabolism is reprogrammed to compensate for this deficiency.Transgenic tomato （Solanum lycopersicum） plants were generated expressing a fragment of the mitochon- drial NAD-dependent isocitrate dehydrogenase gene （SIIDH1） in the antisense orientation. The transgenic plants displayed a mild reduction in the activity of the target enzyme in the leaves but essentially no visible alteration in growth from the wild-type. Fruit size and yield were, however, reduced. These plants were characterized by relatively few changes in pho- tosynthetic parameters, but they displayed a minor decrease in maximum photosynthetic efficiency （Fv/Fm）. Furthermore, a clear reduction in flux through the tricarboxylic acid （TCA） cycle was observed in the transformants. Additionally, bio- chemical analyses revealed that the transgenic lines exhibited considerably altered metabolism, being characterized by slight decreases in the levels of amino acids, intermediates of the TCA cycle, photosynthetic pigments, starch, and NAD（P）H levels, but increased levels of nitrate and protein. Results from these studies show that even small changes in mitochon- drial NAD-dependent isocitrate dehydrogenase activity lead to noticeable alterations in nitrate assimilation and suggest the presence of different strategies by which metabolism is reprogrammed to compensate for this deficiency.

关 键 词：Carbon metabolism nitrogen metabolism PHOTORESPIRATION photosynthesis mitochondria tomato. 

分 类 号：S828.5[农业科学—畜牧学] S63[农业科学—畜牧兽医]