Mycorrhizal specificity of the invasive orchid Oeceoclades maculata in Puerto Rico

Abstract

The terrestrial orchid Oeceoclades maculata is found throughout Puerto Rico. Originally from Africa, it has been called the most widespread orchid around the world. This success has been attributed to its tendency for self-pollination, but may also be due to its relationship with mycorrhizal fungi. Mycorrhizae contribute to plant success by absorbing nutrients and water from the soil. The fungi invade the cells of the root and make globular structures known as pelotons which are digested by the plant. To study this relationship and determine their level of specificity we focus on two techniques: identification of the mycorrhizal fungi present in mature roots by DNA sequencing, and measuring success of seed germination with different fungi. We asked: does O. maculata associate with a wide variety of mycorrhizal fungi or does it specialize? Does specificity vary within stages in development? Low specificity would help the orchid colonize new areas because it would not depend on a single group of fungi. High specificity could contribute to invasiveness if the fungal partner is very widely distributed.