Type B strains of induce severe foliar chlorosis when applied at planting to seeds of symbiotic host and non-host dicotyledonous plants. A Tn5-induced mutant, designated CT4812, of strain CIAT899 that was unable to induce chlorosis was isolated. Cloning and sequencing of the DNA flanking the transposon in CT4812 revealed that the Tn5 insertion is located in a gene similar to which encodes uridylyltransferase/uridylyl-removing enzyme in enteric bacteria. Two marker-exchange mutants with insertions in also failed to induce chlorosis in bean plants. The 5′-most insertion in (in mutant strain ME330) abolished the ability of to utilize nitrate as a sole carbon source, whereas a mutation in further downstream (in mutant strain ME245) did not have an obvious effect on nitrate utilization. A gene similar to the virulence gene overlaps the 3′ end of the homologue. A mutation in had no effect on the ability of CIAT899 to induce chlorosis in bean plants. Therefore the homologue, but not appears to be required for induction of chlorosis in plants by strain CIAT899. A high nitrogen:carbon ratio in the rhizosphere of bean plants also prevented from inducing chlorosis in bean plants. Mutations in either the homologue or had no significant effect on root nodule formation or acetylene reduction activity. A mutation in eliminated motility in The sequence data, the inability of the mutant to utilize nitrate, and the role of the gene in chlorosis induction in plants,a process that is nitrogen regulated, suggest that plays a role in nitrogen sensing in as its homologues do in other organisms.


Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error