Colonization of roots of cultivated Solanum lycopersicum by dark septate and other ascomycetous endophytes.
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 the 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 characterisation and ITS region sequencing of the six sporulating and eight sterile isolates revealed that they belong to different orders of Ascomycota and that the sterile dark septate endophytes did not correspond to the well-known Phialocephala group. Interaction of nine isolates with tomato plantlets were assessed in vitro. No impact on shoot development was revealed, but three isolates caused brown spots in roots. Colonization patterns as analyzed by confocal microscopy differed between the isolates and ranged from epidermal to cortical penetration. Altogether, eleven 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.
Andrade-Linares, D. R.; Grosch, R.; Franken P.; Rexer, K. H.; Kost, G.; Restrepo, S.; Cepero de Garcia, M. C.; Maximova, E. 2011. Colonization of roots of cultivated Solanum lycopersicum by dark septate and other ascomycetous endophytes. Mycologia 103 (4), 710-721.