1Department of Molecular Biology, Agricultural University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands; 2Albrecht von Haller Institute for Plant Sciences, Plant Biochemistry, Göttingen University, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany; 3Department of Biology, Ithaca College, 953 Danby Road, Ithaca, NY 14850, U.S.A.; 4Department of Environmental Horticulture, University of California, Davis 95616, U.S.A.
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Accepted 2 June 2003.
Phylogenetic analyses suggest that, among the members of the Eurosid I clade, nitrogen-fixing root nodule symbioses developed multiple times independently, four times with rhizobia and four times with the genus Frankia. In order to understand the degree of similarity between symbiotic systems of different phylogenetic subgroups, gene expression patterns were analyzed in root nodules of Datisca glomerata and compared with those in nodules of another actinorhizal plant, Alnus glutinosa, and with the expression patterns of homologous genes in legumes. In parallel, the phylogeny of actinorhizal plants was examined more closely. The results suggest that, although relationships between major groups are difficult to resolve using molecular phylogenetic analysis, the comparison of gene expression patterns can be used to inform evolutionary relationships. In this case, stronger similarities were found between legumes and intracellularly infected actinorhizal plants (Alnus) than between actinorhizal plants of two different phylogenetic subgroups (Alnus/Datisca).
major latex protein,
© 2003 The American Phytopathological Society