RESUMO
Shoots of Eucalyptus globulus Labill. cultured on shoot multiplication media containing, on alternate subcultures, 6-benzylaminopurine (BAP) or 6-furfurylaminopurine (kinetin), showed better growth than cultures in which either of the cytokinins was used continuously, or both were used in an equimolar mixture. When BAP was used continuously in the medium (i.e. in every subculture), shoots multiplied but remained stunted and leaves became red and abscised. Kinetin or 6-dimethylallyaminopurine (2iP) used continuously in the medium induced very low multiplication but the shoots did not become red nor did the leaves abscise. Shoots taken from multiplication medium containing BAP and placed on rooting medium with 10 microM indole butyric acid (IBA) produced few roots and often died while on the rooting medium. In contrast, shoots from the multiplication medium containing kinetin produced more roots and remained healthy during the passage on the rooting medium.
RESUMO
Eucalyptus marginata Donn ex Sm. and Pisolithus tinctorius (Pers.) Cok and Couch were co-cultured to obtain ectomycorrhizal formation in vitro. One isolate of P. tinctorius formed mycorrhizas with aseptic seedlings of a juvenile clone derived from a 4-month-old seedling, and four clones derived from crowns of mature trees. A second P. tinctorius isolate formed mycorrhizas with only the clones from mature trees. Successful combinations resulted in formation of a mantle followed by a Hartig net and epidermal cell elongation. The fungal/seedlings or fungal/seedling clone combinations which did not produce ectomycorrhizal roots, were characterized by a mantle but lacked a Hartig net, and formed an abundance of polyphenols throughout the root. Genotype, maturity and fungal specificity are key factors influencing successful ectomycorrhizal formation on E. marginata by P. tinctorius in vitro.
