The requirement for exopolysaccharide precedes the requirement for flavolan-binding polysaccharide in nodulation of Leucaena leucocephala by Rhizobium loti.
Rhizobium loti strain PN4115 (NZP2213 str-1) ineffectively nodulates Leucaena leucocephala, i.e., strain PN4115 induces nodulation (Nod+) and is able to invade these nodules (Inv+), but fails to fix nitrogen (Fix-). Strain PN4115 does not synthesize a flavolan-binding polysaccharide (FBP), which is synthesized by the fully effective (Nod+Inv+Fix+) R. loti strain PN184 (NZP2037 str-1). The FBP may offer protection from prodelphinidin-rich flavolans synthesized by Lc. leucocephala. In this work, we show that exopolysaccharide (EPS)-negative mutants derived from strain PN4115 have a more severe ineffective phenotype (Nod+Inv-Fix-) on Lc. leucocephala than strain PN4115. This suggests that EPS from strain PN4115 is functional during invasion of Lc. leucocephala and that the requirement for EPS precedes the requirement for FBP.
Hotter
G S
GS
Molecular Genetics Unit, Department of Microbiology and Genetics, Massey University, Palmerston North, New Zealand. g.s.hotter@massey.ac.nz
Scott
D B
DB
D002852:Chromatography, Ion Exchange; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D007887:Fabaceae / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial; D016296:Mutagenesis; D009586:Nitrogen Fixation; D010946:Plants, Medicinal; D011134:Polysaccharides / Q000235:genetics / Q000378:metabolism*; D012231:Rhizobium / Q000235:genetics / Q000378:metabolism*
D004269:DNA, Bacterial; D011134:Polysaccharides