Truncated hemoglobins in actinorhizal nodules of Datisca glomerata

K. Pawlowski, K.R. Jacobsen, N. Alloisio, R.F. Denison, M. Klein, J.D. Tjepkema, T. Winzer, A. Sirrenberg, C. Guan, A.M. Berry

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23 Citations (Scopus)


Three types of hemoglobins exist in higher plants, symbiotic, non-symbiotic, and truncated hemoglobins. Symbiotic (class II) hemoglobins play a role in oxygen supply to intracellular nitrogen-fixing symbionts in legume root nodules, and in one case ( Parasponia Sp.), a non-symbiotic (class I) hemoglobin has been recruited for this function. Here we report the induction of a host gene, dgtrHB1, encoding a truncated hemoglobin in Frankia-induced nodules of the actinorhizal plant Datisca glomerata. Induction takes place specifically in cells infected by the microsymbiont, prior to the onset of bacterial nitrogen fixation. A bacterial gene (Frankia trHBO) encoding a truncated hemoglobin with O (2)-binding kinetics suitable for the facilitation of O (2) diffusion ( ) is also expressed in symbiosis. Nodule oximetry confirms the presence of a molecule that binds oxygen reversibly in D. glomerata nodules, but indicates a low overall hemoglobin concentration suggesting a local function. Frankia trHbO is likely to be responsible for this activity. The function of the D. glomerata truncated hemoglobin is unknown; a possible role in nitric oxide detoxification is suggested.
Original languageEnglish
Pages (from-to)776-785
JournalPlant Biology
Issue number6
Publication statusPublished - 2007


  • soybean root-nodules
  • nitric-oxide
  • nitrogenase activity
  • oxygen diffusion
  • mycobacterium-tuberculosis
  • bradyrhizobium-japonicum
  • casuarina-actinorhizae
  • sinorhizobium-meliloti
  • symbiotic hemoglobin
  • arabidopsis-thaliana


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