Caracterización de la comunidad de hongos endófitos asociados a la raíz de Pleurothallis coriacardia y evaluación de su efecto en el desarrollo de sus semillas

Abstract

The family Orchidaceae is recognized as an important plant-group due to their mutualistic interactions with fungi assembling mycorrhiza interactions. Despite the abundant information about mycorrhizal relationships, the knowledge of diversity patterns of endophytic microorganisms at orchid-roots is poorly understood. Particularly, in the Neotropic, the knowledge on Andean orchids and the diversity of microorganisms that inhabits their roots is very limited. We collected samples of roots in a montane forest in southern Andes of Ecuador and characterize the endophytic communities - cultivable and noncultivable – that colonize Pleurothallis coriacardia roots. We report the isolation of cultivable endophytic fungi, related to Psathryrellaceae, a clade poorly studied as mycorrhizal, with a promotor activity in the post-embryonic development of the seeds of P. coriacardia to a testa rupture stage. The community of endophytic microorganisms characterized by molecular methods reports seventy-seven OTU (Operational Taxonomic Units) phylogenetically close to the Atractiellales and Sebacinales orders, while the community of endophytic bacteria reports the presence of sixty-six OTU, mainly cyanobacteria. This molecular analysis confirms postulates of association of tropical orchids to a wide range of taxa recognized as mycorrhizal and endophytes, opening the possibility to clarify the diversity of ecological roles that these organisms may be fulfilling in the plant. Within this context, our results contribute to the knowledge of the high diversity in composition of the entire endophytic community and to the understanding of complex interactions of Andean orchids and their endophytic hosts.