Herrera Hector, Valadares Rafael, Contreras Domingo, Bashan Yoav, Arriagada Cesar
Departamento de Ciencias Forestales, Laboratorio de Biorremediación, Facultad de Ciencias Agropecuarias y Forestales, Universidad de La Frontera, Av. Francisco Salazar, 01145, Temuco, Chile.
Vale Institute of Technology - Sustainable Development, Rua Boaventura da silva 955, Cep 66050-090, Belém, PA, Brazil.
Mycorrhiza. 2017 Apr;27(3):175-188. doi: 10.1007/s00572-016-0733-0. Epub 2016 Oct 29.
Little is known about Orchidaceae plants in Chile and their mycorrhizal associations, a key issue for designing protective actions for endangered species. We investigated root fungi from seven terrestrial orchid species to identify potential mycorrhizal fungi. The main characteristics of Rhizoctonia-like fungi were observed under light microscopy, and isolates were identified through PCR-ITS sequencing. Molecular identification of fungal sequences showed a high diversity of fungi colonizing roots. Fungal ability to germinate seeds of different orchids was determined in symbiotic germination tests; 24 fungal groups were isolated, belonging to the genera Tulasnella, Ceratobasidium, and Thanatephorus. Furthermore, dark septate and other endophytic fungi were identified. The high number of Rhizoctonia-like fungi obtained from adult orchids from the Coastal mountain range suggests that, after germination, these orchids may complement their nutritional demands through mycoheterotrophy. Nonetheless, beneficial associations with other endophytic fungi may also co-exist. In this study, isolated mycorrhizal fungi had the ability to induce seed germination at different efficiencies and with low specificity. Germin ation rates were low, but protocorms continued to develop for 60 days. A Tulasnella sp. isolated from Chloraea gavilu was most effective to induce seed germination of different species. The dark septate endophytic (DSE) fungi did not show any effect on seed development; however, their widespread occurrence in some orchids suggests a putative role in plant establishment.
智利的兰科植物及其菌根共生关系鲜为人知，而这是为濒危物种设计保护行动的关键问题。我们调查了七种陆生兰花物种的根真菌，以确定潜在的菌根真菌。在光学显微镜下观察了类丝核菌真菌的主要特征，并通过PCR-ITS测序对分离株进行了鉴定。真菌序列的分子鉴定表明，定殖于根部的真菌具有高度多样性。在共生萌发试验中测定了真菌使不同兰花种子萌发的能力；分离出24个真菌类群，属于土赤壳属、角担菌属和丝核菌属。此外，还鉴定出了暗隔内生真菌和其他内生真菌。从沿海山脉的成年兰花中获得的类丝核菌真菌数量众多，这表明这些兰花在萌发后可能通过菌根异养来补充其营养需求。尽管如此，与其他内生真菌的有益共生关系也可能同时存在。在本研究中，分离出的菌根真菌具有以不同效率和低特异性诱导种子萌发的能力。萌发率较低，但原球茎持续发育了60天。从加维卢绿花兰中分离出的一种土赤壳菌对诱导不同物种的种子萌发最有效。暗隔内生真菌对种子发育没有任何影响；然而，它们在一些兰花中广泛存在，表明在植物定植中可能发挥作用。
