Mild reductions in mitochondrial NAD-dependent isocitrate dehydrogenase activity result in altered nitrate assimilation and pigmentation but do not impact growth

Mol Plant. 2010 Jan;3(1):156-73. doi: 10.1093/mp/ssp101. Epub 2009 Dec 24.

Abstract

Transgenic tomato (Solanum lycopersicum) plants were generated expressing a fragment of the mitochondrial NAD-dependent isocitrate dehydrogenase gene (SlIDH1) 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 photosynthetic 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, biochemical 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 mitochondrial 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Citric Acid Cycle / genetics
  • Citric Acid Cycle / physiology
  • Isocitrate Dehydrogenase / classification
  • Isocitrate Dehydrogenase / genetics
  • Isocitrate Dehydrogenase / metabolism*
  • Lycopersicon esculentum / enzymology*
  • Lycopersicon esculentum / genetics
  • Lycopersicon esculentum / growth & development
  • Lycopersicon esculentum / metabolism*
  • Mitochondria / enzymology*
  • Nitrates / metabolism*
  • Oligonucleotide Array Sequence Analysis
  • Photosynthesis / genetics
  • Photosynthesis / physiology
  • Phylogeny
  • Pigmentation / genetics
  • Pigmentation / physiology
  • Plant Proteins / classification
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Plants, Genetically Modified / enzymology
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / growth & development
  • Plants, Genetically Modified / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • Nitrates
  • Plant Proteins
  • Isocitrate Dehydrogenase