TABLE 5.

Effects of apigenin, nodD1, and nodSU on Nod factor production and nodulation of L. leucocephala by strains NGR234 and USDA257

Straina	Nod factor productionb		Nodulation of L. leucocephala
	− Apigenin	+ Apigenin
NGR234	0.4 ± 0.2	61.8 ± 9.7	Nod+ Fix+
NGRΔnodD1	0.4 ± 0.3	0.3 ± 0.2	Nod−
NGRΔnodSU	0.3 ± 0.3	5.7 ± 2.5	Nod−
USDA257	0.2 ± 0.2	1.5 ± 1.1	Nod−
USDA257(nodSU)	0.1 ± 0.1	38.3 ± 9.8	Nod+ Fix+

^aNGRΔnodD1, nodD1 mutant of Rhizobium sp. strain NGR234; NGRΔnodSU, nodSU mutant of strain NGR234; USDA257 (nodSU), R. fredii USDA257 transconjugant containing the functional nodSU genes of NGR234. 

^bNod factors were quantified using the tomato cell suspension assay (259). The results are expressed in nanomoles per milliliter of culture corrected to an absorbance at 700 nm of 1 and were taken from references 144, 158, and 214.