Effect of abiotic stress on the endophytic fungal community in Brassica napus L. (winter canola) leaves

Winter canola is an oleaginous plant whose seeds are used in the food and biodiesel industries. Fungal endophytes are found in asymptomatic tissues of almost all plant lineages, promoting positive responses to stress situations. This study aims to characterize the fungal endophytic community of canola leaves (var. Hornet) grown under abiotic stress, comparing them with those plants with no apparent stress signs. Our results showed that canola has a community of endophytic fungi distributed in the Phylum Ascomycota, with members of Alternaria and Stemphylium as dominant groups. We found 231 endophytic fungi strains, belonging to 2 genera and 29 fungal morphotypes. A greater diversity and richness of endophytic fungi were found in canola populations grown on saline soil (14 species, SSP) and waterlogged soil (11 species, WSP). Conversely, the canola population with no apparent abiotic stress (NASP) had only 3 endophytic species. The highest estimated species richness was found in the SSP (17.2), followed by the WSP (12.6), and the NASP (3.4). We also observed NASP showed very low endophyte colonization compared to stressed plants, being 6 and 4 times higher on WSP and SSP, respectively. Additionally, plant parameter analyses showed that canola leaves of SSP and WSP accumulated more water than canola leaves of NASP. The results obtained contribute to the knowledge on the dynamics of the endophytic fungal community associated with canola cultivation in the field, allow estimation of mycodiversity, and might be useful in research aimed at crop growth promotion.