Isolation, identification, and pathogenic effects of Trichoderma spp. from Auricularia auricula

Auricularia auricula, one of the most important edible mushrooms, is affected heavily by Trichoderma. We collected the diseased samples from the main A. auricula cultivation regions to characterize the pathogen and study the effect of Trichoderma spp. on A. auricula species. We identified one Trichoderma species, T. pleuroticola, based on the internal transcribed spacer and morphology characteristics, and two types of A. auricula strains, Heiwei 15 (HW 15) and Hei 29 (H 29), were tested in this work. The growth rate of T. pleuroticola was 3.26–3.52 times higher than that of A. auricula and advantageously competed for living space and nutrients. In confrontation culture, T. pleuroticola completely inhibited the mycelium growth of A. auricula and grew on it, resulting in a diverse impact on HW 15 and H 29. In addition, T. pleuroticola can produce metabolites with antibacterial activity. The inhibition rate of volatile metabolites to H-29 and HW 15 was 13.46% and 10.44%, and the inhibition rate of nonvolatile metabolites to H-29 and HW 15 was 36.04% and 31.49%, respectively. Further analysis showed that these antifungal activities inhibiting Auricularia auricula growth were mainly attributed to the organic compounds from T. pleuroticola, nonanal, tyrosine, beta-sitosterol, and wortmannin. In short, T. pleuroticola was a highly pathogenic fungi in the production of A. auricula. T. pleuroticola can affect the normal growth of A. auricula hypha, and its metabolites also have inhibitory effects on A. auricula hypha.