|Wang, Congli - Chinese Academy Of Sciences|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2018
Publication Date: 4/10/2018
Citation: Wang, C., Masler, E.P., Rogers, S.T. 2018. Responses of Heterodera glycines and Meloidogyne incognita infective juveniles to root tissues, root exudates, and root extracts from three plant species. Plant Disease. https://doi.org/10.1094/PDIS-09-17-1445-RE.
DOI: https://doi.org/10.1094/PDIS-09-17-1445-RE Interpretive Summary: Plant-parasitic nematodes attack all crops of agricultural importance, causing over $10 billion in losses annually to U.S. farmers. Because several chemical pesticides used to control nematodes have been withdrawn from use, growers face a critical need for the discovery of environmentally and economically sound nematode control agents. One approach to discovering new means of controlling nematodes is to identify ways to control their behavior and infectivity using naturally derived compounds. We discovered that soybean cyst and root-knot nematodes are repelled and attracted differently by chemical components from plant roots. These discoveries are significant because they reveal that plant derived molecules have significant potential as natural and specific agents to suppress nematode infection since they can target plant-parasitic nematode behaviors needed to survive. Consequently, this information will be used by researchers in the agrochemical and agricultural biotechnology industries who are developing safe, selective methods for nematode control.
Technical Abstract: The infective juvenile (J2) stage of endoparasitic plant nematodes uses plant chemical signals, released from roots, to localize and infect hosts. We examined the behaviors of soybean cyst nematode (Heterodera glycines) and root-knot nematode (Meloidogyne incognita) J2s in the presence of root signals from marigold (Tagetes patula), soybean (Glycine max), and pepper (Capsicum annuum). Signals were obtained from sources commonly used in phytoparasitic nematode chemotaxis studies-root tips, root exudates, and root extracts. Root tips from each plant species attracted M. incognita, but H. glycines was attracted only to soybean. In contrast, root exudates prepared from marigold, pepper, or soybean seedlings were attractive to H. glycines but were repellent to M. incognita. Root extracts had the same effect as exudates. Fractionation of exudates by reversed phase HPLC (CH3CN/0.1%TFA) revealed highly polar and less polar components affecting behaviors. Fractions eluting at 12% CH3CN from all three plants attracted H. glycines and repelled M. incognita. None of the less polar HPLC fractions (> 15% CH3CN) affected H. glycines but those from G. max and T. patula repelled M. incognita. Differences among exudates and effects of fractionation on behavior are discussed.