Natural forest succession after a volcanic eruption: mycorrhizal and fungal communities related to seedling regeneration

MOGUILEVSKY, D.; PUNTIERI, J.; FERNÁNDEZ, N.V.; FONTENLA, S.; CARRON, AYELEN INÉS; CORNEJO, P.

S.C. de Bariloche

Simposio; II International Symposium Mycorrhizal Symbiosis in South America; 2019

Natural forest succession after a volcanic eruption: mycorrhizal and fungal communities related to seedling regenerationD. Moguilevsky1,2,*, A. Carron1,2, N.V. Fernández1,2, J. Puntieri2,3, P. Cornejo4 and S.B. Fontenla1 1 Laboratorio de Microbiología Aplicada, Centro Regional Universitario Bariloche, UNComahue - IPATEC, Bariloche, Río Negro, Argentina2 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina3 Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural (IRNAD), Universidad Nacional de Río Negro, Bariloche, Argentina4 Centro de Investigación en Micorrizas y Sustentabilidad Agroambiental, CIMYSA, Facultad de Ingeniería y Ciencias, Universidad de La Frontera, Temuco, Chile5 Scientifc and Technological Bioresource Nucleus, BIOREN-UFRO, Universidad de La Frontera, Temuco, Chile* Email: dmoguile@gmail.comThe 2011 Puyehue Cordón Caulle´s eruption affected large areas of Nothofagus pumilio (lenga) forests. In some places, the tephra layer is 50 cm thick, buried the understory vegetation and formed a brand new substrate for plants and microorganisms. After the eruption, the natural regeneration of N. pumilio started, but there is no information about its ectomycorrhizal behaviour and the importance of this symbiosis for this natural process. Ectomycorrhizas (EM) are present in all Nothofagus species, and in mature N. pumilio trees colonization rates are in general ≥70%. Our objective was to analyse how tephra influenced N. pumlio´s EM colonization, seedling development and root fungal communities over time. In 2013, in a forest with high tephra deposition (50 cm), we buried 15 pots into the tephra layer, which were filled with soil obtained from under the tephra. Two six-months-old seedlings (growing in the tephra) were transplanted into each pot (?soil seedlings?, SS) and nearby seedlings remained growing in the tephra (?tephra seedlings?, TS). One, four and five years after the experiment was established (2014, 2017 and 2018) we collected seedlings from both substrates (SS and TS) in addition to roots from adult trees. We analysed several morphometric measures of the seedlings and EM abundance in seedlings and adults. For studying the composition of different rhizosphere fungal communities we performed several Denaturing Gradient Gel Electrophoresis (DGGE). Total DNA was extracted from the rhizosphere and nested PCRs were carried out, using different sets of primers for analysing Total Fungi (ITS1F-ITS4), Ascomycetes (ITS1F-ITS4A) and Basidiomycetes (ITS1F-ITS4B). All the individuals had EM. The first year (2014), EM colonization was lower in TS (49%) than in SS and adults (75% and 70%, respectively). In 2017 and 2018 the EM colonization was similar between all the samples (63-86%). For the morphometric measures, in the first year, no differences were found between TS and SS, but in 2017 SS were bigger than the TS and in 2018 SS seedlings were smaller than TS. For the three fungal communities analyzed, in 2014 there was a clear separation between TS and SS, but in 2017 they were more similar to each other. All this results suggest that the tephra is becoming an appropriate substrate for N. pumilio development. The tephra allows the germination and survival of seedlings, has EM infective capacity, and root colonization increases over time. After a high impact disturbance, the re-establishment of the native inoculum in the tephra and the occurrence of EM in N. pumilio seedlings seems to be important factors for the forest regeneration process.