Identification and Characterization of the nodD Gene in Rhizobium leguminosarum strain 1001. Andrea Squartini. Dipartimento di Biotecnologie Agrarie, Università di Padova, via Gradenigo 6, 35131 Padova, Italy. Ron J. M. Van Veen(2), Tonny Regensburg-Tuink(2), Paul J. J. Hooykaas(2), and Marco P. Nuti(1). (1) Dipartimento di Biotecnologie Agrarie, Università di Padova, via Gradenigo 6, 35131 Padova, Italy, and (2) Department of Plant Molecular Biology, University of Leiden, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands.. MPMI 1:145-149. Accepted 21 March 1988. Copyright 1988 The American Phytopathological Society.

A gene library of the symbiotic 240-kb plasmid of Rhizobium leguminosarum strain 1001 was constructed in pUC18. The clones showing homology with a 6.6-kb fragment containing nodEFDABC from the Sym plasmid pRL1JI were detected by colony hybridization. Additional probes from the symbiotic region of pRL1JI were used to localize the corresponding genes on the map of pRle1001a. The relative positions of nod and nif gene clusters are different than those of pRL1JI. A comparison of the amino acid sequence for NodD from pRle1001a with NodD proteins from other Rhizobium species showed a high degree of sequence conservation at the amino terminus of the protein.