Autoradiographische und cytochemische Untersuchungen zum Assimilattransfer in der ektotrophen Mykorrhiza

2001

S. 108-120

40 Lit. Ang.

Unselbständiges Werk

200084588

Autoradiographic and cytochemical investigations were carried out to examine the carbohydrate transfer after hoch 14 CO2 assimilation and the localization of the H+-ATPase in mycorrhizal pine roots inoculated with the basidiomycete Suillus bovinus (L. ex Fr.) Kuntze. The experiments showed that in mycorrhizal systems the fungal symbiotic partner has a strong sink strength for carbohydrates and that a high portion of photosynthates are translocated via the stele to the mycobiont. In median parts of the longitudinal axis of a mycorrhizal root a zone with a strong labelling can be seen, where the Harting net is well differentiated and where obviously the main transfer of carbohydrates to the fungus takes place. In contrast, in basal or apical zones of the mycorrhizal root lower exchange activities were observed. In this main exchange zone also the highest activity of the H +-ATPase of the fungal and plant plasma membrane in the mycorrhizal interface was localized indicating (1) that both membranes are capable for active uptake processes and (2) that in ectomycorrhizal association a bidrectional trnasfer of carbohydrates and nutrient across the same interface structure is realized. The results are discussed with respect to the differentiation of the Hartig net and the exchange processes occuring acros this mycorrhizal interface.