Colonization of roots of cultivatedSolanum lycopersicumby dark septate and other ascomycetous endophytes

Abstract

Tomato (Solanum lycopersicum L.) roots from four different crop sites in Colombia were surface sterilized and 51 fungal isolates were obtained and conserved for further analysis. Based on microscopical observations and growth characteristics, 20 fungal isolates corresponded to genus Fusarium, six presented asexual conidia different from Fusarium, eight were sterile mycelia, seven of which had dark septate hyphae and 17 did not continue to grow on plates after being recovered from conservation. Growth on different media, detailed morphological characterization and ITS region sequencing of the six sporulating and eight sterile isolates revealed that they belonged to different orders of Ascomycota and that the sterile dark septate endophytes did not correspond to the well known Phialocephala group. Interactions of nine isolates with tomato plantlets were assessed in vitro. No effect on shoot development was revealed, but three isolates caused brown spots in roots. Colonization patterns as analyzed by confocal microscopy differed among the isolates and ranged from epidermal to cortical penetration. Altogether 11 new isolates from root endophytic fungi were obtained, seven of which showed features of dark septate endophytes. Four known morphotypes were represented by five isolates, while six isolates belonged to five morphotypes of putative new unknown species.

Interactions between dark septate endophytes, ectomycorrhizal fungi and root pathogens in vitro

“…PMI_412, all DSE strains altered H. annosum Han1 colonies (Table S2). Similar results were reported in the literature, with Cadophora, Phialocephala and Leptodontidium decreasing the growth of other phytopathogenic fungi (Andrade-Linares et al 2011;Tellenbach et al 2013;Khastini et al 2014;Terhonen et al 2016). However, except for studies on P. fortinii, no study examined the interaction between other DSE species and the root pathogens P. citricola, H. annosum or P. ultimatum (Rasanayagam and Jeffries 1992;Tellenbach and Sieber 2012;Tellenbach et al 2013;Terhonen et al 2016).…”

Dark Septate Endophyte Improves Drought Tolerance in Sorghum

“…A kind of phytohormones substances (IAA) was identified in culture medium from two DSE strains Helgardia ericae (Gay and Debaud, 1987) and Phialophora sp. (Rommert et al, 2002), Andrade-Linares et al (2011) also found that DSE indirectly improved hormone signal transduction and hormone-regulated gene expression in host plants. Other possible reason was that DSE fungi produced a wide range of enzymatic capabilities, which increased the efficient utilization of organic matter and other available nutrients for host plants (Caldwell et al, 2000).…”

Profundae diversitas: the uncharted genetic diversity in a newly studied group of fungal root endophytes

“…Fungal diversity was also high in a review of the endophytes in grass species, with some assemblage similarity to ours (Sánchez Márquez et al 2012). The only study which specifically focused on characterising fungal root endophytes from a single species (tomato, Solanum lycopersicon ) also revealed the presence of many putative new species (Andrade-Linares et al 2011). The presence of many other unculturable endophytes in many plants is likely, with even relatively new single orders of endophyte found to be ubiquitous (Weiss et al 2011).…”

“…In recent years, DNA-based studies of endophytic organisms isolated from the wild and cultivated plant systems have led to an increasing level of awareness of the high phylogenetic diversity within fungal endophytes (Andrade-Linares et al 2011; Sánchez Márquez et al 2012; Ek-Ramos et al 2013). Some of these endophytes are localised to specific tissue types and some are found systemically.…”