Characterization of mycorrhiza associating with Encyclia tampensis and its effect on plant health

Abstract

Starting in the late 1800’s orchids were heavily poached, leaving many species to reach critically low numbers. Coupled with habitat loss and urbanization many orchid populations were extirpated in southern Florida. Due to lack of endosperm, orchid seeds are reliant on specific mycorrhizal fungi to obtain nutrients to enable embryo development resulting in very low germination rates in nature. This obligatory relationship with mycorrhizal fungi complicates orchid re-establishment. The research project aims are (1) to evaluate the correlation between phenotypic traits and optimal growing conditions in various micro-climate conditions, and (2) to assess the range of mycorrhizal diversity in urban and botanic garden settings. The native orchid, Encyclia tampensis, was sampled from naturally occurring and lab propagated orchids at Fairchild Tropical Botanic Garden (FTBG), Naples Botanical Garden (NBG), and Downtown Doral Park (DDP) on oak, cypress, and palm trees. Phenotypic measurements (chlorophyll content, light intensity, height on the tree, number of leaves, root and shoot lengths) and root sampling (fungal isolations, DNA identification) were conducted. Increased SPAD and NDVI values measuring chlorophyll content as a plant health parameter were observed at FTBG, while DDP and NBG had comparable values indicating the suitability of botanic gardens and urban spaces as reintroduction sites for orchid. Across all 3 sites and host trees, two distinct clades of mycorrhizal fungi within the genus Tulasnella were recovered. The results of this study will help maximize current conservation and reintroduction programs within developed urban areas and botanical gardens for best management practices on orchids.