Plant Science

Not Like Peas in a Pod

Science's STKE  05 Jun 2007:
Vol. 2007, Issue 389, pp. tw199
DOI: 10.1126/stke.3892007tw199

Legumes, such as peas and beans, have residing within nodules in their roots symbiotic bacteria that fix atmospheric nitrogen. The rhizobial symbiont produces signaling molecules, the so-called Nod factors, that are recognized by the plant. Giraud et al. (see the Perspective by Downie) report the complete genomic sequences of two photosynthetic Bradyrhizobium strains that produce nodules in their host plant roots but lack the nodABC genes and Nod factors. Instead, during this atypical symbiosis, a purine derivative may act as a signal molecule to trigger root nodule organogenesis.

E. Giraud, L. Moulin, D. Vallenet, V. Barbe, E. Cytryn, J.-C. Avarre, M. Jaubert, D. Simon, F. Cartieaux, Y. Prin, G. Bena, L. Hannibal, J. Fardoux, M. Kojadinovic, L. Vuillet, A. Lajus, S. Cruveiller, Z. Rouy, S. Mangenot, B. Segurens, C. Dossat, W. L. Franck, W.-S. Chang, E. Saunders, D. Bruce, P. Richardson, P. Normand, B. Dreyfus, D. Pignol, G. Stacey, D. Emerich, A. Verm├ęglio, C. M├ędigue, M. Sadowsky, Legumes symbioses: Absence of Nod genes in photosynthetic Bradyrhizobia. Science 316, 1307-1312 (2007). [Abstract] [Full Text]

J. A. Downie, Infectious heresy. Science 316, 1296-1297 (2007). [Summary] [Full Text]