Mushroom extract induces resistance in passion fruit and in vitro control of Xanthomonas axonopodis pv. Passiflorae

Abstract

In vitro inhibitory capacity of Lentinula edodes and Agaricus blazei extracts on Xanthomonas axonopodis pv. passiflorae and their capacity to induce resistance in passion fruit in a greenhouse are evaluated. Aqueous crude extracts (CEs) were prepared by hydrating the basidiocarp dry powder with distilled water for 24h, at 4 ºC. CEs were added in test tubes at concentrations 10, 20, 30 and 40%, whilst control contained water only. Bacterial suspension (1 mL) was added to each tube (108 cfu.mL-1) and incubated in the dark at 28 °C for 24h. The bacterial suspension was measured by a spectrophotometer at 550 nm. Passion fruit cultivars IAC-275 and Epagri Oval Grande were sown on two substrates in a greenhouse: substrate 1 (SB) - horizon B soil; substrate 2 (SBC) - 40% soil from horizon B + 40% organic compost + 20% roughage (rice husk). A. blazei aqueous crude extract (ACE) treatments were applied at 20% and 40%; L. edodes ACE 20% and 40%; biofertilizer Agromos® 1% and control (without treatment) were started when the plants were in the 4-6 leaf stage. Sprays were done weekly, totaling four applications. Seven days after the first application and seven days after the last spraying, leaves were collected to evaluate chitinase, peroxidase and β-1,3-glucanase activity seven days. In vitro aqueous mushroom extracts inhibited the CFU of X. axonopodis pv. passiflorae and increase in the activity of peroxidase and β-1,3-glucanase was observed in passion fruit plants in the greenhouse.