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Novel Aspects of Symbiotic Nitrogen Fixation Uncovered by Transcript Profiling with cDNA Arrays

May 2002 , Volume 15 , Number  5
Pages  411 - 420

Gillian Colebatch , 1 Sebastian Kloska , 2 Ben Trevaskis , 1 Susanne Freund , 1 Thomas Altmann , 1 and Michael K. Udvardi 1

1Max Planck Institute for Molecular Plant Physiology, Am Mühlenberg 1, 14476 Golm, Germany; 2Scienion AG, Volmerstr. 7a, 12489 Berlin, Germany

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Accepted 14 February 2002.

An array of 2,304 cDNA clones derived from nitrogen-fixing nodules of Lotus japonicus was produced and used to detect differences in relative gene transcript abundance between nodules and uninfected roots. Transcripts of 83 different genes were found to be more abundant in nodules than in roots. More than 50 of these have never before been identified as nodule-induced in any species. Expression of 36 genes was detected in nodules but not in roots. Several known nodulin genes were included among the nodule-induced genes. Also included were genes involved in sucrose breakdown and glycolysis, CO2 recycling, and amino acid synthesis, processes that are known to be accelerated in nodules compared with roots. Genes involved in membrane transport, hormone metabolism, cell wall and protein synthesis, and signal transduction and regulation of transcription were also induced in nodules. Genes that may subvert normal plant defense responses, including two encoding enzymes involved in detoxification of active oxygen species and one that may prohibit phytoalexin synthesis, were also identified. The data represent a rich source of information for hypothesis building and future exploration of symbiotic nitrogen fixation.

© 2002 The American Phytopathological Society