SPATIAL AND TEMPORAL VARIATION OF ENDOPHYTIC COMMUNITIES ASSOCIATED TO THE PHYLLOSPHERE OF OLIVE CULTIVARS

Abstract

Fungal endophytes are micro-organisms that colonize healthy plant tissues without causing disease symptoms. They are described as plant growth and disease resistance promoters and have shown antimicrobial activity through the production of antagonistic bioactive substances. Studies combining spatial and temporal distribution of endophytic communities in terms of abundance and diversity in the phyllosphere of olive cultivars have been poorly explored. Thus, this study aims to investigate the abundance and diversity of endophytic communities at three sampling seasons and sites, in the Alentejo region south of Portugal. Additionally and because the impact of some pathogenic fungi (e.g. Colletotrichum spp.) vary according to olive cultivars; Galega vulgar, Cobrançosa and Azeiteira, with different degree of susceptibility, were sampled. The 1868 fungal isolates obtained belong to 48 OTUs representing 31 fungal genera. Autumn season and cultivar Galega vulgar showed the significant highest values in terms of endophytic abundances and diversities, the mainly dominant factors that shaped the communities. At the site level a low variability was found in terms of diversity and abundance of the endophytic communities. This study reinforces the importance of exploring the combined spatio-temporal distribution of the endophytic biodiversity in different olive cultivars, highlighting the limited information on isolation and characterization of endophytes from important cultivars and the need for more detailed analyses in this field. Knowledge about endophytic communities may help to better understand their functions in plants hosts, such as the ecological dynamics between pathogenic fungi and beneficial colonizers, which could be explored as biocontrol agents in the future.