Chemotaxis response of Meloidogyne incognita to volatiles and organic acids from root exudates

Chemotaxis plays an important role in food-finding, mate-finding, response to host plants and other aspects of nematode interactions. In this study, chemotaxis responses of Meloidogyne incognita second-stage juveniles (J2) to seven plant hosts were investigated. Chemotaxis volatiles from root exudates were analyzed by gas chromatography-mass spectrometry, from which four attractive compounds were identified as the tridecane, 1-docosene, 1-octadecene and 2-hexyl-1-decanol. 1-docosene was distributed in root exudates of all seven plants, while the other compounds were found only in some root exudates. In addition, organic acids commonly found in plant root exudates were screened. Among the 16 types of organic acids, six organic acids could attract J2 of M. incognita. Malic acid, oxalic acid and lactic acid were found to demonstrate chemotactic effect on M. incognita J2 and were distributed differently in the seven plants. These results indicate that volatiles and organic acids secreted from different plants possess the ability to attract the J2 of M. incognita. This study provides insight into the signaling mechanism between root-knot nematodes and host plants, which may thus help develop more effective biological control methods.