Microorganismos involucrados en la absorción de fósforo en la Isla Rey Jorge, Antártida

Deschampsia antarctica is one of the two plant species that have successfully to colonized and adapted to Antarctica. The interaction with microorganisms adapted to the Antarctic environment could partly explain its presence, so this work focused on studying the interactions of D. antarctica with groups of endophytic fungi and bacteria associated with the phosphorus (P) cycle. The objectives were: to evaluate the potential for mycorrhizal and DSE colonization of Antarctic soils; to determine the presence of arbuscular mycorrhizae (MA) and dark septate endophytic fungi (DSE) in roots of D. antarctica; to quantify the presence of glomalin associated proteins in Antarctic soils and to determine the number of rhizospheric bacteria solubilizing P. On King George Island, during the summers of 2019,2020 and 2021, soil and root samples of D. Antarctica were taken at two sites with contrasting contents of available P: Drake (high P) and Suffield Point (low P). Mycorrhizal and DSE colonization and easily removable glomalin (GFE) were quantified. Total aerobic heterotrophic bacteria (BHTA) and P-solubilizing bacteria (BSP) were counted from the rhizosphere of D. antarctica. The mycorrhizal potential was studied in trap culture using soil from both sites, at the Faculty of Agronomy. The presence of mycorrhizae in D. antarctica was high, 46 and 52% and that of DSE 19 and 30% in Drake and Punta Suffield, respectively, with not significant differences between sites, except in DSE. The results obtained in terms of the glomalin fraction GFE show small differences to favor of Drake (1,34 and 1,46 mg glomalin /g soil) and 1,28 and 1,13 mg at Suffield Point in 2020 and 2021 respectively. A higher BSP/BHTA ratio was found in Drake, indicating a positive relationship between P content and the presence of BSP. The presence of bacteria and fungi linked to the P cycle in Antarctica represents a possible strategy for plants to acquire this nutrient and survive in these extreme conditions.