ABSTRACT
Conditions required for the combined culture of either Glomus caledonium (Nicol. &Gerd.) Trappe &Gerdemann or Glomus mosseae (Nicol. &Gerd.) Gerdemann &Trappe with suspension-cultured plant cells have been investigated. Sucrose levels (0.05 to 0.5%, w/v) lower than those used for growth of plant cells were optimal for hyphal growth of both G. caledonium and G. mosseae. In vitro hyphal growth from chlamydospores of G. caledonium was stimulated by addition of cells of wheat (Triticum aestivum L. cv. Maris Butler), lucerne (Medicago sativa L. cv. Europ) and potato (Solanum tuberosum L. cv. Maris Piper). The presence of wheat cells similarly stimulated hyphal growth from chlamydospores of G. mosseae. Further tests on the effect of lucerne cells on G. caledonium indicated that a volatile substance was involved in the improvement of hyphal growth.
Subject(s)
Polysaccharides, Bacterial/analysis , Rhizobium/analysis , Acetates/analysis , Chromatography, Paper , Galactose/analysis , Glucose/analysis , Nitrogen Fixation , Plants , Polysaccharides, Bacterial/isolation & purification , Pyruvates/analysis , Rhizobium/growth & development , Rhizobium/metabolism , Species Specificity , Symbiosis , Uronic Acids/analysisABSTRACT
1. beta-Hydroxy-beta-methyl[3-(14)C]glutaryl-CoA is efficiently incorporated into rubber on incubation with Hevea brasiliensis latex, and the incorporation is diminished in the presence of unlabelled mevalonate. beta-Hydroxy-beta-methylglutaric acid is not utilized for rubber synthesis, but inhibits the formation of rubber from beta-hydroxy-beta-methylglutaryl-CoA. 2. The incorporation of beta-hydroxy-beta-methylglutaryl-CoA into rubber is stimulated equally by NADP(+) and NADPH and less so by NAD(+) and NADH. ATP is slightly stimulatory and CoA is inhibitory. 3. beta-Hydroxy-beta-methylglutaryl-CoA reductase is concentrated in the sediment (bottom fraction) formed by centrifuging latex at low speed and the enzyme is unstable in the absence of cysteine or GSH. The formation of NADPH takes place in the latex serum. 4. There is a marked seasonal variation in the extent of beta-hydroxy-beta-methylglutaryl-CoA incorporation into rubber in latex, but mevalonate incorporation is relatively constant. This observation, together with the finding that beta-hydroxy-beta-methylglutaryl-CoA reduction is the rate-limiting step in the formation of rubber from beta-hydroxy-beta-methylglutaryl-CoA, suggests that the conversion of beta-hydroxy-beta-methylglutaryl-CoA into mevalonate is of importance in the regulation of rubber synthesis. 5. Evidence suggesting that beta-hydroxy-beta-methylglutaryl-CoA lyase is present in H. brasiliensis latex has been obtained.
