Understanding Fungus-Nematode Interactions to Control the Meloidogyne Javanica Species |

ABSTRACT:

This study was aimed at elucidating the parasiticcapabilities of Trichoderma isolates on the RKN, M. javanica and theirbiocontrol activities against the nematode. Parasitism is probably an importantmode of action and one of the initial steps of this process is attachment. Thenematode’s gm enabled fungal attachment and enhanced parasitic capabilities ofthe isolates (except T. harzianum), which could also utilize gm as a nutrientsource. It has also been found to trigger proteolytic and chitinolytic enzymeproduction by the fungus (Sharon et al. unpubl.). This combination of enzymesis required to disrupt the eggshell, although chitinolytic capacity is probablythe most important activity on the eggshells. Trichoderma asperellum GH-11exhibited lower parasitic capabilities that might be related to insufficientproteolytic activity of this isolate, while T. atroviride presented thegreatest efficiency for parasitism of J2s, probably because of its highproteolytic activities (Sharon et al. unpubl.). Production of proteinase Prb1in this isolate has been studied and its involvement in fungal parasitism hasbeen shown. A transgenic T. atroviride line (P2) containing multiple copies ofthe prb1 gene also exhibited improved biocontrol activity of M. javanica insoil experiments and in parasitism assays on agar in vitro.The gm alsotriggered an immobilization effect on J2s produced by T. atroviride and T.asperellum isolates 203 and 44. This effect might be the result of enzymes andmetabolites, such as peptaibols, the activities of which may actsynergistically.