Cyclic [beta]-1,6 -1,3 Glucans Are Synthesized by Bradyrhizobium japonicum Bacteroids within Soybean (Glycine max) Root Nodules

Abstract

We have previously reported that free-living cultures of Bradyrhizobium species produce nove1 oligosaccharides that are cyclic, contain between 10 and 13 glucose residues, and are linked by 8-

Cyclic [beta]-1,6-1,3-Glucans of Bradyrhizobium japonicum USDA 110 Elicit Isoflavonoid Production in the Soybean (Glycine max) Host

“…The cyclic /3-1,2-glucans of Rhizobium are believed to provide functions Recently, we showed that bacteroids of B. japonicum USDA 110 isolated from mature soybean nodules (i.e. 6 to 9 weeks after inoculation) also contain high levels of cyclic /3-1,6-1,3-glucans (Gore and Miller, 1993). This result suggests that the cyclic /3-1,6-1,3-glucans may provide functions during the later stages of nodule development.…”

“…Next, the neutral cyclic P-glucan fractions were isolated using a DEAE-cellulose column. These chromatography procedures have been previously described (Miller et al, 1990;Gore and Miller, 1993). Finally, the purified neutral cyclic P-glucan fractions were desalted on a Sephadex G15 column using 7% (v/v) I-propanol as previously described (Gore and Miller, 1993).…”

Isolation of salt-sensitive mutants of Sinorhizobium meliloti strain Rm1021

“…Although it is unlikely that the concentration of salt in the rhizosphere is equivalent to that which was used to screen for mutants, it is pertinent to consider that elevated concentrations of salt also increase the osmotic stress encountered by the bacteria. It has been suggested that bacteria may need to adapt to changes in osmolarity during symbiosis (Gore & Miller, 1993;Spaink, 2000;Vedam et al, 2003). Therefore, the use of this screen, followed by assaying the mutants for a subtle phenotype (competition for nodule occupancy), has the potential to unveil not only genes that affect salt sensitivity but also those that affect growth in the rhizosphere or during symbiosome development.…”

Soyabean glyceollins: biological effects and relevance to human health

“…Typical biotic elicitors causing glyceollin production in soyabean include b-1,3-1,6-oligoglucoside, b-1,3-glucan and cyclic b-1,6-1,3-glucan, which are cell wall components of pathogenic or mutualistic symbiotic micro-organisms (32) . For instance, cyclic b-1,6-1,3-glucans synthesised by both free-living cells and bacteroids of B. japonicum are active elicitors of glyceollins in soyabean (33,34) . Glyceollin synthesis is also induced by abiotic elicitors including iodoacetate, UV, Tx-100, and metal ions such as Fe, Cu, Hg and Ag (21) as well as during fungal infection.…”