Araucaria araucana (Molina) K. Koch is a conifer distributed in the Andean-Patagonian forests in the south of Argentina and Chile. The main objective of this work was to relate the different root classes appearing in A. araucana to mycorrhizal behavior. Samples were collected in three different sites in the Lanín National Park (NW Patagonia, Argentina). Two different root classes were present in A. araucana: longitudinal fine roots (LFR) and globular short roots (GSR). Both had extensive

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... izal arbuscular symbiosis (AM) and presented abundant hyphae and coils in root cells, a characteristic of the anatomical Paris-type. Dark septate fungal endophytes were also observed. Values of total AM colonization were high, with similar partial AM% values for each root class. Seasonal differences were found for total and partial colonization, with higher values in spring compared to autumn. Regarding the percentage of fungal structures between root classes, values were similar for vesicles and arbuscules, but higher coil percentages were observed in GSR compared to LFR. The percentages of vesicles increased in autumn, whereas the arbuscule percentages increased in spring, coinciding with the plant growth peak. Results show that both root classes of A. araucana in Andean-Patagonian forests are associated with AM fungi, which may have ecological relevance in terms of the importance of this symbiosis, in response to soil nutrient-deficiencies, especially high P-retention.La conífera Araucaria araucana (Molina) K. Koch se encuentra distribuida en los bosques Andino-Patagónicos de Argentina y Chile. En este trabajo se relacionaron las diferentes clases morfológicas de raíces presentes en la especie con el comportamiento micorrícico. Las muestras fueron tomadas en tres sitios del Parque Nacional Lanín (NO de Patagonia, Argentina). Se observaron dos clases diferentes de raíces: raíces finas longitudinales (RFL) y raíces cortas globulares (RCG). Ambas clases presentaron una importante simbiosis micorrícico-arbuscular (MA), [...]