ABSTRACT
Arbuscular mycorrhizas are the most ancient mycorrhizal association (Taylor 1995) and are found in more than 80% of the plant species (Smith and Read 2008). In a limited number of plant groups, the arbuscular association was replaced by an ectomycorrhizal association (Smith and Read 2008). Certain families such as Pinaceae and Fagaceae exclusively have ectomycorrhizal associations, but there are also several isolated lineages of ectomycorrhization in other families (Brundrett 2002). For instance, in the Nyctaginaceae, only a few ectomycorrhiza forming species are known; these are found in Neea Ruiz & Pav. (Harley and Smith 1983), Guapira Aubl. (syn Torrubia, Harley and Smith 1983) and Pisonia L. (Ashford and Allaway 1982). All three genera belong to the tribe Pisonieae (Bittrich and Kühn
1Institute of Evolution and Ecology, Plant Evolutionary Ecolology, Eberhard-Karls-University Tübingen, Auf der Morgenstelle 1, D-72076 Tübingen, Germany. 2Departamento de Ciencias Naturales, Universidad Técnica Particular de Loja, Loja, Ecuador. *Corresponding author: ingeborg.haug@uni-tuebingen.de
1993). Species of Neea were found to be ectomycorrhizal in the Amazonian rainforest (Singer and Araujo 1979, Janos 1980a,b, Tedersoo et al. 2010) and in Peru (Alexander and Högberg 1986) or ecto-and arbuscular mycorrhizal in an Amazonian lowland rain forest (St. John 1980a,b), in the South of Venezuela (Moyersoen 1993), and in French Guiana (Béreau et al. 1997). Species of Guapira were found to be ecto-and arbuscular mycorrhizal in the South of Venezuela (Moyersoen 1993) and ectomycorrhizal in Western Amazonia (Tedersoo et al. 2010). Ectomycorrhizas of Pisonia grandis R.Br. were described from coral cays in the Great Barrier Reef (Ashford and Allaway 1982, Chambers et al. 2005) and from the Seychelles (Ashford and Allaway 1985, Suvi et al. 2010). The mycorrhizas associated with Pisonia grandis have a unique structure with a hyphal mantle, Hartig net, and transfer cells (Ashford and Allaway 1982, 1985). Arbuscular mycorrhizal infection was detected in other species of Nyctaginaceae, namely Boerhavia repens, Bougainvillea spectabilis, Mirabilis jalapa, Pisonia umbellifera (Koske et al. 1992) and Pisonia seychellarum (Suvi et al. 2010). A low degree of mycorrhization with only vesicles and mycelium was reported for Boerhavia diffusa (Rachel et al. 1989) and no mycorrhization was reported for Mirabilis jalapa, Boerhavia diffusa (Muthukumar and Udaiyan 2000) and Boerhavia coccinea (Khan 1974). Based on these results, the Nyctaginaceae were considered to be a predominantly non-mycorrhizal family with isolated ectomycorrhizal and arbuscular mycorrhizal species (Tester et al. 1987, Brundrett 2002, Wang and Qiu 2006). However, a very small percentage of the ca. 400 species included in the family (Daly and Roberts 2004) have been investigated so far (Wang and Qiu 2006). In summary, the available data of ectomycorrhizas of Nyctaginaceae show typical and unique structures. Only a few fungal partners are identifi ed with molecular methods. In this study we aim to enhance the knowledge of morphological features of ectomycorrhizas in the neotropics and to identify their fungal partners.
