Soluble Carbohydrates in Mycorrhized and Non-Mycorrhized Fine Roots of Spruce Seedlings

Sugar for my honey: Carbohydrate partitioning in ectomycorrhizal symbiosis

“…While there are some indications in literature that some fungi might have sucrolytic activity, others clearly do not (Willard et al, 1987;Salzer and Hager, 1991;Schaeffer et al, 1995). It is thus commonly accepted that sucrose, which is excreted by plant root cells into the common apoplast of the plant/fungus interface, is hydrolyzed by a plantderived invertase in ectomycorrhizal symbiosis (Lewis and Harley, 1965a;Salzer and Hager, 1991;Rieger et al, 1992;Hampp and Schaeffer, 1995;Nehls, 2004). The lack of an invertase in (at least many) ectomycorrhizal fungi is a profound difference to phytopathogenic (e.g.…”

“…In contrast, the glycogen content was stable during the whole period of investigation (Wallenda, 1996). Longitudinal dissection of single ectomycorrhizas showed that in the presumably most intense interaction zone the fungus-specific disaccharide trehalose dominates, indicating a conversion of glucose into this storage compound in functional mycorrhizas (Rieger et al, 1992). In Lactarius the glycogen content was high during winter, declined until summer (strong fungal propagation), and was restored during autumn (Genet et al, 2000).…”

Amanita

“…The total amount of sucrose + glucose + fructose is about 30% higher in non-ECM fine roots, sucrose being the dominant sugar in both ECM and non-ECM fine roots (Rieger et al 1992). A histochemical quantification of metabolite pools in different sections of mycorrhized root tips (P. abies/ A. muscaria) exhibited a distinct gradient.…”

“…Using freeze-dried material and dissecting techniques (see Rieger et al 1992), four zones from tip to base of controls and infected fine roots were distinguished and compared. In this case, the ratio of ATP : ADP of zones involved in mutual interaction between both partners (Hartig net region) was higher compared to non-infected samples.…”

Eucalypt NADP-Dependent Isocitrate Dehydrogenase1

“…These changes affect enzymes of the N-assimilation pathways, such as NADP-dependent glutamate dehydrogenase (Martin and Botton, 1993), glycolysis, and the pentose phosphate pathway (Bilger et al, 1989;Schaeffer et al, 1996). As a consequence, the amino acid and carbohydrate contents of mycorrhizal roots are drastically modified (Rieger et al, 1992;Martin and Botton, 1993;Turnbull et al, 1995;Ek, 1997). Knowledge of the regulation of the fungal and root biochemical pathways and comparison of these with those operating in ectomycorrhizae might help in understanding how the symbiosis metabolism is regulated.…”