Disease relevance of noeI

• A 2-O-methylfucose moiety is present in the lipo-oligosaccharide nodulation signal of Bradyrhizobium japonicum [1].
• We have recently reported that an impaired proline metabolism in rhizobium meliloti leads to a reduced nodulation efficiency and competitiveness on alfalfa roots [2].
• The Azorhizobium caulinodans strain ORS571 nodulation genes nodSUIJ were located downstream from nodABC [3].
• Identification and use of actinomycetes for enhanced nodulation of soybean co-inoculated with Bradyrhizobium japonicum [4].

High impact information on noeI

• The latest work shows that quorum sensing can be linked to various symbiotic phenomena including nodulation efficiency, symbiosome development, exopolysaccharide production, and nitrogen fixation, all of which are important for the establishment of a successful symbiosis [5].
• Population density control of the nodulation genes involves NolA and NodD2, both of which function in tandem to repress nod gene expression [6].
• Several soybean genotypes have been identified which specifically exclude nodulation by members of Bradyrhizobium japonicum serocluster 123 [7].
• The nodulation-complementing region is located approximately 590 base pairs transcriptionally downstream from nodD2 [7].
• Lipopolysaccharide (LPS) purified from Bradyrhizobium japonicum R110d, a Gram-negative bacterium that normally infects and induces nodulation in soybean roots in vivo, inhibits intercellular communication between the soybean cells in a dose-dependent manner [8].

Chemical compound and disease context of noeI

• Isoflavonoid signal molecules from soybean (Glycine max (L.) Merr.) seed and root exudate induce the transcription of nodulation (nod) genes in Bradyrhizobium japonicum [9].
• In this work, we sought to test whether chemical inhibitors of flavonoid-induced nod gene expression in Bradyrhizobium japonicum could be identified and utilized to affect interstrain competition for nodulation of soybeans [10].

Biological context of noeI

• The cosmid clone which complemented R. meliloti ndvB mutants for synthesis of beta-1,2-glucans and effective nodulation of alfalfa was mapped and subcloned [11].
• When IFS was silenced using RNA interference in soybean hairy root composite plants, these plants had severely reduced nodulation [12].
• Mutant strain HS111 exhibits a delayed-nodulation phenotype, a result of its inability to initiate successful nodulation promptly following inoculation of the soybean root [13].
• Competition for nodulation was studied with young cultures of two wild-type strains differing only in their antibiotic resistance, the N-starved cultures being the most competitive [14].
• These genes, present in tandem on a 4.2-kilobase HindIII fragment, appear in one copy each on the symbiotic plasmid and do not hybridize to the Rhizobium meliloti common nodulation region [15].

Anatomical context of noeI

• Wild-type cells pretreated in soybean root exudates or seed lectin did not exhibit a delay in nodulation at this cell concentration [13].

Associations of noeI with chemical compounds

• Microscopic observation of plant roots showed that butanol extract of B. japonicum strain USDA110 cultures induced for nod gene expression elicited root hair deformation, an early event in the nodulation process [1].
• Surprisingly, pre-treatment of B. japonicum or exogenous application to the root system of either of the major soybean isoflavones, daidzein or genistein, failed to restore normal nodulation [12].
• However, use of a genistein-hypersensitive B. japonicum strain or purified B. japonicum Nod signals rescued normal nodulation in IFS-silenced roots, indicating that the ability of isoflavones to modulate auxin transport is not essential to nodulation [12].
• The promoters of two isoflavone synthase genes respond differentially to nodulation and defense signals in transgenic soybean roots [16].
• Nodulation assays revealed that none of the Canarian isolates nodulated Glycine max or Leucaena leucocephala, but all nodulated Acacia pendula, C. proliferus, Macroptilium atropurpureum, and Vigna unguiculata [17].

Analytical, diagnostic and therapeutic context of noeI

• However, nodulation of soybean plants treated 5 days after emergence with chlorimuron-ethyl at standard application rates was impaired: a 38% decrease in the number of nodules per plant was observed four weeks after treatment [18].

References