title: Salicylic acid inhibits indeterminate-type nodulation but not determinate-type nodulation.
abstract: LCOs (lipochitin oligosaccharides, Nod factors) produced by the rhizobial symbiote of Vicia sativa subsp. nigra (vetch, an indeterminate-type nodulating plant) are mitogenic when carrying an 18:4 acyl chain but not when carrying an 18:1 acyl chain. This suggests that the 18:4 acyl chain specifically contributes to signaling in indeterminate-type nodulation. In a working hypothesis, we speculated that the 18:4 acyl chain is involved in oxylipin signaling comparable to, for example, signaling by derivatives of the 18:3 fatty acid linolenic acid (the octadecanoid pathway). Because salicylic acid (SA) is known to interfere with oxylipin signaling, we tested whether nodulation of vetch could be affected by addition of 10(-4) M SA. This concentration completely blocked nodulation of vetch by Rhizobium leguminosarum bv. viciae and inhibited the mitogenic effect of 18:4 LCOs but did not affect LCO-induced root-hair deformation. SA did not act systemically, and only biologically active SA derivatives were capable of inhibiting nodule formation. SA also inhibited R. leguminosarum bv. viciae association with vetch roots. In contrast, addition of SA to Lotus japonicus (a determinate-type nodulating plant responding to 18:1 LCOs) did not inhibit nodulation by Mesorhizobium loti. Other indeterminate-type nodulating plants showed the same inhibiting response toward SA, whereas SA did not inhibit the nodulation of other determinate-type nodulating plants. SA may be a useful tool for studying fundamental differences between signal transduction pathways of indeterminate- and determinate-type nodulating plants.
authors.affiliation: Institute of Molecular Plant Sciences, Clusius Laboratory, Leiden University, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands. spronsen@rulbim.leidenuniv.nl
authors.forename: Paulina C
authors.initials: PC
authors.lastname: van Spronsen
authors.forename: Teun
authors.initials: T
authors.lastname: Tak
authors.forename: Anita M M
authors.initials: AM
authors.lastname: Rood
authors.forename: Anton A N
authors.initials: AA
authors.lastname: van Brussel
authors.forename: Jan W
authors.initials: JW
authors.lastname: Kijne
authors.forename: Kees J M
authors.initials: KJ
authors.lastname: Boot
mesh_terms: D007887:Fabaceae / Q000382:microbiology*; D008070:Lipopolysaccharides / Q000378:metabolism; D000070116:Lotus / Q000382:microbiology; D000455:Medicago sativa / Q000382:microbiology; D018532:Pisum sativum / Q000382:microbiology; D027805:Phaseolus / Q000382:microbiology; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology*; D016961:Rhizobium leguminosarum / Q000254:growth & development; D020156:Salicylic Acid / Q000378:metabolism / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D016962:Sinorhizobium meliloti / Q000254:growth & development; D013025:Glycine max / Q000382:microbiology; D013045:Species Specificity; D013559:Symbiosis / Q000187:drug effects* / Q000502:physiology; D029921:Trifolium / Q000382:microbiology; D033022:Vicia sativa / Q000382:microbiology
chemical_list: D008070:Lipopolysaccharides; C092736:Nod factor, Rhizobium leguminosarum; D020156:Salicylic Acid