Table 1. Bacterial strains, plasmids and DNA fragments.

	Relevant characteristics	Reference or source
Rhizobium
8401	Rhizobium leguminosarum bv. viciae cured of its symbiotic plasmid, Strr	(44)
Escherichia coli
S17-1	294 recA, chrom, RP4 derivative	(24)
Plasmids
pKT230	IncQ broad-host-range plasmid; Strr, Kanr	(45)
pIJ1518	1.8 kb BclI fragment with nodD in pKT230; Kanr	(4)
pMP220	lacZ downstream of a multi-cloning site; IncP broad-host-range plasmid; Tcr	(9)
pMP221	Opposite multi-cloning site in pMP220	Stored in this laboratory
pUW	nodA promoter (–75 to +57) cloned into the EcoRI–PstI sites of pUC119	This study
pUO13	nodA promoter (–75 to +57) with the O13 D-half cloned into the EcoRI–PstI sites of pUC119	This study
pMP221O13	EcoRI–PstI fragment cloned from pUO13 into pMP221	This study
Fragments
TnodboxT	5′-TTGAATATCCATTCCATAGATGATTGCCATCCAAACAATCAATTTTACCAATCTTTCGG-3′	This study
	3′-CTTATAGGTAAGGTATCTACTAACGGTAGGTTTGTTAGTTAAAATGGTTAGAAAGCCTT-5′
TDhalfT	5′-TTGAATATCCATTCCATAGATGATTGCCATACTGACTGACTGACTGACTGACTGACTGA-3′	This study
	3′-CTTATAGGTAAGGTATCTACTAACGGTATGACTGACTGACTGACTGACTGACTGACTTT-5′
TPhalfT	5′-TTTGCATGCATGCATGCATGCATGCATGATCCAAACAATCAATTTTACCAATCTTTCGG-3′	This study
	3′-ACGTACGTACGTACGTACGTACGTACTAGGTTTGTTAGTTAAAATGGTTAGAAAGCCTT-3′