Rhizopines are nodule-specific compounds that confer an intraspecies competitive nodulation advantage to strains that can catabolize them. The rhizopine (3-O-methyl-scyllo-inosamine, 3-O-MSI) catabolic moc gene cluster mocCABRDE(F) in Rhizobium leguminosarum bv. viciae strain 1a is located on the Sym plasmid. MocCABR are homologous to the mocCABR gene products from Sinorhizobium meliloti. MocD ...

In Rhizobium leguminosarum bv. viciae, quorum-sensing is regulated by CinR, which induces the cinIS operon. CinI synthesizes an AHL, whereas CinS inactivates PraR, a repressor. Mutation of praR enhanced biofilms in vitro. We developed a light (lux)-dependent assay of rhizobial attachment to roots and demonstrated that mutation of praR increased biofilms on pea roots. The praR mutant out-compete...

There is a growing need to characterize the effects of environmental stressors at the molecular level on model organisms with the ever increasing number and variety of anthropogenic chemical pollutants. The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), as one of the most widely applied pesticides in the world, is one such example. This herbicide is known to have non-targeted undesirable eff...

Salicylic acid is an important signalling molecule in plant-microbe defence and symbiosis. We analysed the transcriptional responses of the nitrogen fixing plant symbiont, Rhizobium leguminosarum bv viciae 3841 to salicylic acid. Two MFS-type multicomponent efflux systems were induced in response to salicylic acid, rmrAB and the hitherto undescribed system salRAB. Based on sequence similarity s...

Post-translational modification expands the functionality of the proteome beyond genetic encoding, impacting many cellular processes. Cleavage of the carboxyl terminus is one of the many different ways proteins can be modified for functionality. Gel-electrophoresis and mass spectrometric-based techniques were used to identify proteins impacted by deficiency of a C-terminal protease, CtpA, in Rh...

Boron (B) is an essential micronutrient for the development of nitrogen-fixing root nodules in pea (Pisum sativum). By using monoclonal antibodies that recognize specific glycoconjugate components implicated in legume root-nodule development, we investigated the effects of low B on the formation of infection threads and the colonization of pea nodules by Rhizobium leguminosarum bv viciae. In B-...

The symbiotic plasmid (pSym) of Rhizobium leguminosarum bv. trifolii 4S5, which carries Tn5-mob, was successfully transferred into Agrobacterium tumefaciens A136 by using a conjugation method. The resulting transconjugants induced the development of ineffective nitrogen-fixing nodules on the roots of white clover seedlings. Depending on the manner in which the pSym was retained, the transconjug...

In a field experiment conducted during Rabi 2002-03 at Pantnagar, seed inoculation with Rhizobium leguminosarum bv. viceae (LB-4), PSB (Bacillus megaterium) and PGPR LK-786 (Kurthia sp.) alone significantly increased the nodule number at different intervals, nodule dry weight at 45 and 90 DAS, plant dry weight at 70 and 90 DAS and N uptake by grain and straw in lentil over the uninoculated cont...