Caracterização e identificação de um fungo micorrízico antártico

Abstract

The biota of Antarctica, more than other continents, is dominated by microorganisms, such as fungi. The distribution of fungi in the Antarctic continent relates to substrates such as soils, rocks and plants. The species Colobanthus quitensis (Kunth) Bartl is the only dicot that colonized the Antarctic ecosystem and has mechanisms to survive in harsh conditions, with a favorable substrate colonization of fungi. This study aimed to characterize morphologically and physiologically the fungus isolated from the rhizosphere samples of C. quitensis. To this end, samples were taken during the Brazilian Antarctic Expedition XXXI (2012-2013), samples of C. quitensis roots that grew in the fields of melting of King George Island, located in the Maritime Antarctic. Inoculant (9 mm diameter), obtained from C. quitensis roots and preserved among Capelani were used for the activation of the mycelium, the culture medium for potato dextrose agar (PDA) maintained at pH 4 and photoperiod chamber at a temperature of 26 ° C ± 1 in the absence of light. For better visualization of the reproductive structures and hyphae of the fungus culture slide was performed using 5 Petri dishes containing PDA medium and maintained in Photoperiod camera on 10ºC ± 1 temperature for 30 days in the dark. From this technique, staining nucleus was performed and established that the isolated has chambered hyphae, hyphae and mononuclear. As the basis of morphological analyzes the fungus was identified belonging to the genus Geomyces Traaen. Phylogenetic and molecular analysis using ITS regions of the subunit 5.8S rRNA demonstrated the identity of this isolated as belonging to class Eurotiomycetes OE Erikss. & Winka and species Geomyces vinaceus Dal Vesco and Pseudogymnoascus roseus Raillo. Different temperatures (5, 10, 15, 25 and 30 ± 1 ° C), were tested to verify the relationship of various temperatures with the production of isolated biomass. Comparing the average of these five temperatures, was obtained as a result of weighing the wet and dry mycelia those after 33 days of growth, where the fungus was not able to grow at a temperature of 30 ± 1 ° C, and showed better growth mycelial weighing in wet and dry at a temperature of 15 ± 1 ° C, thus a psicrófilo fungus. In determining the pathogenicity where Lolium multiflorum Lam was treated with the isolated fungus extract in two treatments 1.0ml and 2.0ml, L. multiflorum showed a better growth in air treatment with 1.0ml, statistically however the fungus showed no effect on plant.