Molecular and cultural characterization of Morchella spp. from disturbed environments of central-southern Chile

Abstract

In Northwestern Patagonia (Chile), three species of Morchella from undisturbed environments have been identified to date: Morchella tridentina, Morchella andinensis and Morchella aysenina, all belonging to the Elata clade and associated mainly with Nothofagus forests. In this study, the search for Morchella specimens was extended to disturbed environments in Central-Southern Chile, to further explore Morchella species diversity in the country, which is still very limited. The Morchella specimens were identified through multilocus sequences analysis, and the mycelial cultures were characterized, establishing comparisons with specimens from undisturbed environments. To the best of our knowledge, these results reveal for the first time in Chile the presence of the species Morchella eximia and Morchella importuna, and in the case of the last one also the first record in South America. These species were found associated almost exclusively with harvested or burned coniferous plantations. The in vitro mycelial characterization revealed certain inter- and intra-specific patterns of the morphology, such as pigmentation, mycelium type, and development and formation of sclerotia, which varied according to growth media and incubation temperature. The growth rates (mm/day) and mycelial biomass (mg) were significantly influenced by the temperature (p < 0.05), with maximum rates (>10 mm/day) and biomass (approx. 20 mg) between 20 and 24 °C, while a significant growth reduction (70-90%) was observed at 28 °C, mainly in the species from undisturbed environments. Potato-dextrose (PDA) medium stimulated the greatest mycelial density and sclerotia formation in most of the isolates, mainly in M. eximia (UDEC-LAF 236 isolate) which recorded the best mycelial growth performance. Among isolates, UDEC-LAF 236 also showed the best performance in sclerotia production (>350 sclerotia/dish) in 10 days of growth. This study contributes to the knowledge of the diversity of Morchella species in Chile by broadening the species range to those from disturbed environments. It also provides molecular and morphological characterization of the in vitro cultures of different Morchella species. The report on M. eximia and M. importuna, species known as cultivable, adapted to local climatic and edaphic conditions could represent the first step to developing artificial Morchella cultivation methods in Chile.

Keywords: Chilean morel diversity; Elata clade; Morchella eximia; Morchella importuna; Mycelial characterization.