Persistent fungal root endophytes isolated from a wild barley species suppress seed-borne infections in a barley cultivar

Ten fungal root endophytes were isolated from wild populations of Hordeum murinum ssp. murinum L. and inoculated onto untreated seeds of a barley cultivar using five artificial and one soil-based growth media. A co-inoculant of all ten isolates as well as two individual isolates successfully suppressed the development of seed-borne fungal infections on germinated and ungerminated seed. The two most successful isolates were also the most persistent as re-emergents and may provide real potential for development as crop inoculants. All isolates were more persistent in barley exposed to light after germination. The soil-based compost was associated with the greatest degree of seed-borne infection suppression, and the most successful artificial medium for suppressing seed-borne infections was also the medium with the most similar pH to the soil at the sampling sites. These results suggest a direct antagonistic effect of the fungal isolates on seed-borne pathogens without the induction of plant defences.