Histological Observation on the Symbiotic Relationships Between Gastrodia elata and Rhizomorph of Armillaria mellea

The histological studies were conducted to investigate the symbiotic relationships between Gastrodia elata and Armillaria mellea by using light and electron microscopes. The fungus, A. mellea, penetrated into the cortex of G. elata, in which endomycorrhizal mycelia in the cortical cells appeared to be dissolved and digested, and seemed to be consequently used as nutritional sources for G. elata growth. Staining of infected tissues revealed that protein- and fat-like substances were localized in the cells. The nuclei of cells infected by the fungal mycelia were hypertrophied 1.5 to 2 times as those without the fungal infection.