Effects of culture filtrates from the nematophagous fungus Verticillium leptobactrum on viability of the root-knot nematode Meloidogyne incognita

Abstract

Filtrates of three isolates of the nematophagous fungus Verticillium leptobactrum were evaluated for their nematicidal activity against the root-knot nematode Meloidogyne incognita. The filtrates inhibited egg hatching, with maximum toxicity observed for isolate HR21 at 50% (v:v) dilution, after 7 days exposure. Filtrates also inactivated second-stage juveniles (J2) at 10-50% dilutions. A scanning electron microscopy study of treated eggs showed severe alterations caused by the filtrate of isolate HR43 on M. incognita eggs, which appeared collapsed and not viable, suggesting the production of chitin-degrading enzymes or other active compounds.

Influence of egg parasitic fungus, Engyodontium aranearum against root knot nematode, Meloidogyne incognita

“…In the present study, the culture filtrate of the egg parasitic fungus E. aranearum significantly suppressed the hatching of root knot nematode eggs. Similar effects on hatching and juvenile mortality of cyst and root Shinya et al (2008) and Regaieg et al (2010).A number of nematophagous fungi are known to have proteolytic and chitinolytic activities which cause alteration in eggs cuticular structure, changes in egg shell permeability or cause perforations in the cuticle which allows seepage of toxic metabolites into the eggs and cause physiological disorders (Webb et al, 1972;Jatala et al, 1985;Lopez -Llorca, 1990). These factors may have important role in the inhibition of egg hatching of root knot nematode.…”

“…Similarly, toxin-producing fungi affect nematodes by the production of nematicidal compounds (Dong et al, 2006). A scanning electron microscopy study of treated eggs showed severe alterations caused by the filtrate of isolate HR43 (P. chlamydosporia) on M. incognita eggs, which appeared collapsed and not viable, suggesting the production of chitin-degrading enzymes or other active compounds (Regaieg et al, 2010).…”

“…In the present study, the culture filtrate of the egg parasitic fungus E. aranearum significantly caused high juvenile mortality. Reddi Kumar et al (2008a), Shinya et al (2008) and Regaieg et al (2010) revealed that lower number of root knot nematode and cyst nematode eggs hatched and higher juvenile mortality was observed using egg parasitic fungi. Effect of culture filtrate of E. aranearum on attraction of M. incognita juveniles: The isolate E. aranearum reduced juveniles attraction towards tomato root by 79.29 per cent over control and it was followed by P. Dababat (2007) and Dababat and Sikoro (2007) who reported that the endophytes inoculated plants exudates reduced the total number of nematodes attracted to the inoculation area by upto 80 per cent over uninoculated control.…”

Detection and biocontrol potential of Verticillium leptobactrum parasitizing Meloidogyne spp.

“…Previous finding showed that culture filtrate from the same V. leptobactrum isolates induced juvenile mortality and inhibited M. incognita egg hatching. A scanning electron microscopy (SEM) study of treated eggs showed severe alterations caused by the filtrate of isolate HR43 on M. incognita eggs suggesting that enzyme or toxin-based strategies, are part of the V. leptobactrum nematocidal behavior (Regaieg et al 2010). In this study it was possible to quantify the antagonist DNA over the RKN egg masses with nested Real-time PCR.…”

“…Morgan-Jones and Rodriguez-Kabana (1981) and Godoy et al (1982) showed that V. leptobactrum species isolated from cysts of Heterodera glycines can parasitize eggs of both H. glycines and M. arenaria. Recently it has been reported that culture filtrates of three Tunisian V. leptobactrum strains exhibited an important nematicidal activity against eggs and second-stage juveniles of M. incognita (Regaieg et al 2010). In the present work we developed assay and diagnostic procedure to detect the fungus on egg masses, evaluating its efficacy as a RKN biocontrol agent in comparison with other NFs, and the results are herein exposed.…”