Nod Genes and Nod Factors of Rhizobium Species NGR234

High‐resolution transcriptional analysis of the symbiotic plasmid of Rhizobium sp. NGR234

“…In contrast to nod genes, most nif and fix homologues are grouped into a single 55 kb cluster ( fixU to y4xE), which has been spared disruption by insertion (IS) or transposon‐like sequences (Freiberg et al ., 1997). So far, only four of the 24 putative regulators of transcription encoded by pNGR234 a have been the subject of detailed investigations: nodD 1 (Relić et al ., 1993a), nodD 2 (Fellay et al ., 1998), syrM 1 (Hanin et al ., 1998) and y4sM (Perret et al ., 1994).…”

nodD2 of Rhizobium sp. NGR234 is involved in the repression of the nodABC operon

“…Part of this broad host range can be explained by the ability of the NodD1 protein to interact with a wide variety of flavonoids and related compounds, such as vanillin (Le Strange et al ., 1990). NGR234 possesses three other nodD homologues: nodD 2, syrM 1 and syrM 2, but a nodD 1 mutant is unable to initiate nodulation on any plant tested (Relić et al ., 1993). In this work, we show that the nodD 2 gene of NGR234 is required for the formation of nitrogen‐fixing nodules and is involved in the repression of the nodABC operon.…”

Flavonoid-Inducible Modifications to Rhamnan O Antigens Are Necessary for Rhizobium sp. Strain NGR234-Legume Symbioses

“…The microbiological techniques used have been described by Lewin et al (34). Analysis of DNA and cloning and sequencing procedures have been published (19,46). Various mutants of Rhizobium sp.…”

“…Although it is clear that Nod factors allow rhizobia to penetrate the legume root (6,46,47), other carbohydrates as well as proteins are needed for infection thread development and subsequent steps in nodule formation. Among these, cell surface polysaccharides of rhizobia are believed to be involved in infection thread initiation, nodule invasion, and host specificity.…”