Evaluation of oyster mushroom strains for resistance to Pseudomonas tolaasii by inoculation in spawned substrates

Bacterial brown blotch disease, caused by Pseudomonas tolaasii, has been one of the most serious bacterial diseases of the oyster mushroom. Resistance to disease has been a priority in breeding programs for the oyster mushroom. In this study, a set of 37 Pleurotus ostreatus strains was tested for resistance to the pathogen P. tolaasii by two methods, with inoculations on pileus and spawned substrate under controlled environmental conditions. The results showed that the protocol with inoculation on spawned substrate was sensitive and adequate for testing resistance of oyster mushroom to brown blotch disease. According to the disease severity of fruiting bodies with inoculation on spawned substrates, strain ACCC50618 was resistant; ACCC50236 was moderate resistant; and the others were susceptible to the pathogen P. tolaasii (ACCC 01267). However, it was difficult to differentiate the resistance of P. ostreatus strains to P. tolaasii by inoculation on the pileus. This is the first report about resistance evaluation of P. ostreatus to brown blotch disease.