Structural identification of the iipo-chitin oligosaccharide nodulation signals of Rhizobium loti |
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| Authors: | Isabel M López-Lara Jorrit D J van den Berg Jane E Thomas-Oates John Glushka Ben J J Lugtenberg Herman P Spaink |
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| Institution: | Institute of Molecular Plant Sciences, Leiden University, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands.;Bijvoet Center for Biomolecular Research. Department of Mass Spectrometry, Utrecht University, Sorbonnnelaan 16, 3584 CA Utrecht, The Netherlands.;Complex Carbohydrate Research Center, 220 Riverbend Road, Athens, Georgia 30602, USA. |
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| Abstract: | Rhizobium loti is a fast-growing Rhizobium species that has been described as a microsymbiont of plants of the genus Lotus. Nodulation studies show that Lotus plants are nodulated by R loti, but not by most other Rhizobium strains, indicating that R. loti produces specific lipo-chitin oligosaccharides (LCOs) which are necessary for the nodulation of Lotus plants. The LCOs produced by five different Rhizobium ioti strains have been purified and were shown to be N-acetylglucosamine pentasaccharides of which the non-reducing residue is N-methylated and N-acylated with c/s-vaccenic acid (C18:1) or stearic acid (C18:O) and carries a carbamoyl group. In one R. loti strain, NZP2037, an additional carbamoyl group is present on the non-reducing terminal residue. The major class of LCO molecules is substituted on the reducing terminal residue with 4-O-acetylfucose. Addition of LCOs to the roots of Lotus plants results in abundant distortion, swelling and branching of the root hairs, whereas spot inoculation leads to the formation of nodule primordia. |
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