Successful Tulasnella amonilioides isolation from wild Cattleya intermedia and effectiveness of the mycobiont on in vitro propagation of this threatened Orchidaceae

Abstract

This is the first study that report symbiosis in Cattleya, aiming to isolate and identify mycorrhizal fungi capable of promoting germination of this orchid, and to evaluate the development of symbiotically propagated individuals. We compared seed germination percentage, growth index and morphometric variables of seedlings propagated symbiotically in OMA medium with individuals that were non-symbiotically propagated in MS medium. Fungi isolates were identified by phylogenetic analysis and eight of the nine isolates that were efficient in C. intermedia propagation were identified as Tulasnella amonilioides. The mycobiont improved C. intermedia seed germination and plant development when compared with OMA medium without fungi (negative control). Seedlings propagated by symbiotic culture with T. amonilioides produced more leaves and longer roots, while shoot height and number of roots were lower than for seedlings propagated in MS medium with the addition of activated charcoal. Fresh mass of seedlings propagated by symbiotic and asymbiotic techniques were equal, except when seedlings were grown in MS without activated charcoal. Tulasnella amonilioides enhances the in vitro propagation of C. intermedia and provides plants that facilitate symbiotic processes in reintroduction environments.