Wood-associated fungi produce volatile organic compounds toxic to root-knot nematode

Abstract

Since volatiles do not leave residues in food and cause low toxicity to humans, they can act as a skeleton for new nematicidal molecules, once they have demonstrated activity against phytonematodes. The aim of this study was to evaluate the effect of volatile organic compounds (VOCs) released by wood-associated fungi on controling second-stage juveniles (J2) of Meloidogyne incognita. All 28 wood-associated fungi isolates produced VOCs which caused in excess of 76 % immobility in exposed J2 of M. incognita. The fungus isolate VOCs also caused significant mortality compared to control when J2 were exposed to them. After 6 h of exposure, the fungus species Epicoccum nigrum and Schizophyllum commune produced VOCs that immobilized exposed J2 compounds, in relation to the control. When J2 were inoculated into tomato under greenhouse conditions, the M. incognita infectivity and reproduction were reduced by exposure to the VOCs. Volatiles produced by most of the fungi isolates and analyzed by gas chromatograph coupled to a mass spectrometer (CG-MS), included alcohols, esters, terpenes, and ketones. Certain compounds appeared only in S. commune or in E. nigrum suggesting their involvement in the high level of damage caused to nematode reproduction on tomato. Volatiles emitted by wood fungi demonstrated another mode of action of these microorganisms in nature.

Nematicidal screening of essential oils and potent toxicity of Dysphania ambrosioides essential oil against Meloidogyne incognita in vitro and in vivo

“…A similar result was observed with essential oil from Cinnamomum cassia (L.) J.Presl, reducing the number of galls and eggs caused by M. incognita in soya bean (Jardim et al, 2017). However, in the current study a greater reduction in the number of eggs compared with the number of galls was observed, an effect encountered in other studies (Barros, Campos, Silva, Lopez, et al, 2014;López, Campos, Júnior, et al, 2017;Pimenta, Ferreira, Pedroso, & Campos, 2017). Barros, Campos, Silva, Lopez, et al (2014) suggest that the drastic reduction in egg numbers compared with galls may be due to inability of the feeding site to provide enough nutrients for the female, with resulting poor egg production.…”

Annulohypoxylon sp. FPYF3050 produces volatile organic compounds against the pine wood nematode, Bursaphelenchus xylophilus

“…Nematode-endoparasite fungi produce numerous lunate conidia that adhere to nematodes, killing them (Shih & Tzean, 1999). Other fungi produce toxic secondary metabolites that immobilise and kill nematodes (Freire et al, 2012;Yang et al, 2012;Pimenta et al, 2017).…”

“…Some studies suggested that the VOCs of some endophytic fungi were able to inhibit the growth of plant pathogens by augmenting host defence responses against pathogens (Macías-Rubalcava et al, 2010). A series of endophytic fungi were recently found to produce VOCs that inhibited nematodes (Freire et al, 2012;Yang et al, 2012;Pimenta et al, 2017). Pimenta et al (2017) reported that VOCs of 28 endophytic fungal isolates immobilised more than 76% of secondstage juveniles (J2) of Meloidogyne incognita.…”

“…A series of endophytic fungi were recently found to produce VOCs that inhibited nematodes (Freire et al, 2012;Yang et al, 2012;Pimenta et al, 2017). Pimenta et al (2017) reported that VOCs of 28 endophytic fungal isolates immobilised more than 76% of secondstage juveniles (J2) of Meloidogyne incognita. The fungal species Epicoccum nigrum and Schizophyllum commune produced VOCs that immobilised J2 after 6 h exposure.…”

“…The fungal species Epicoccum nigrum and Schizophyllum commune produced VOCs that immobilised J2 after 6 h exposure. VOCs emitted by 13 fungi isolated from coffee roots caused more than 40% immobility of J2 M. incognita (Pimenta et al, 2017). However, there is no information on the action of volatile gases from endophytic fungi on pine wood nematodes.…”