Suppression of rice blast disease by autoclaved water extract from the spent mushroom substrate of Lyophyllum decastes

Abstract

Rice blast causes significant crop losses worldwide. To manage this blight, we investigated the protective effects of an autoclaved water extract of fresh spent mushroom substrate (AWESMS) of hatakeshimeji (Lyophyllum decastes Sing.) on rice blast development. When rice plants at the four-leaf stage were sprayed with AWESMS, followed by inoculation with a spore suspension of the rice blast fungus Magnaporthe oryzae at 2, 4, 6, 8, 10, and 14 days after treatment, blast lesion formation in leaves was markedly inhibited compared to those plants pretreated with either distilled water alone or autoclaved water extract from substrate not inoculated with the mushroom (AWEMS). Spore germination, appressorial formation, and mycelial growth of M. oryzae were not inhibited in the presence of AWEMS or AWESMS, suggesting that inhibition of lesion formation is due to the induction of host resistance. A protective effect of AWESMS was systemically observed, suggesting that AWESMS may be a useful source of novel plant activators for rice blast. The use of spent mushroom substrate for plant disease control may offer a new method for the recycling and management of waste from mushroom cultivation.