Volatile compounds produced by Fusarium spp. isolated from Meloidogyne paranaensis egg masses and corticous root tissues from coffee crops are toxic to Meloidogyne incognita

Abstract

Meloidogyne species produce egg masses containing nutrients which may serve as feeding substrate for rhizospheric fungi. In the present work we isolated fungi form Meloidogyne paranaensis egg masses. Amongst the fungi isolated 67% belonged to the genus Fusarium and, within those, 52% of the isolates were of the species F. oxysporum. Isolates from F. oxysporum and F. solani significantly reduced M. incognita infectivity and reproduction in tomato when J2 were exposed to fungal volatiles, causing up to 100% immobility in in vitro tests. Water exposed to the volatile compounds produced by fungi and mixed to the J2 suspension caused toxicity in M. incognita J2 and reduced infectivity and reproduction of nematodes inoculated in tomato, when compared to the control. Using gas chromatography-mass spectrometry (GC-MS), the volatile compounds produced by F. oxysporum and F. solani were identified and gathered in six main categories: esters, alcohols, phenols, aldehydes, carboxylic acids and sesquiterpenes, making up a total of 23 molecules. For the first time, 12 molecules from various chemical groups were identified in the water exposed to the volatiles from F. oxysporum and F. solani. A lower number of molecules were detected in the toxic water when compared with the vapors produced by fungi. Within these molecules, various have been already reported as having high nematicidal activity. Thus, F. oxysporum and F. solani fungi from M. paranaensis egg masses produce volatile compounds with antagonistic activity to M. incognita.