Responses ofHeterodera glycinesandMeloidogyne incognitaInfective Juveniles to Root Tissues, Root Exudates, and Root Extracts from Three Plant Species

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) J2 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 high-performance liquid chromatography (HPLC) (acetonitrile [CHCN] and 0.1% trifluoroacetic acid) revealed highly polar and less polar components affecting behaviors. Fractions eluting at 12% CHCN from all three plants attracted H. glycines and repelled M. incognita. None of the less polar HPLC fractions (>15% CHCN) 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.

Cyst nematode bio‐communication with plants: implications for novel management approaches

“…11,48,49 Bulb extracts of Narcissus tazetta significantly reduced H. glycines J2 motility and attraction to soybean root tip, 50 while root diffusates and extracts from marigold, soybean, and pepper were attractive. 48,51 However, the identities of the mediating compounds remain unknown. Identification of these compounds can provide opportunities for genetic manipulation to reduce J2 attraction and infection.…”

“…For instance, as reported in a recent review G. pallida is attracted to root phytochemicals including α‐solanine, linalool, indole acetic acid, ethephon, salicylic acid, methyl jasmonate and mannitol (Table S1). 11,48,49 Bulb extracts of Narcissus tazetta significantly reduced H. glycines J2 motility and attraction to soybean root tip, 50 while root diffusates and extracts from marigold, soybean, and pepper were attractive 48,51 . However, the identities of the mediating compounds remain unknown.…”

Constituents Leached by Tomato Seeds Regulate the Behavior of Root-Knot Nematodes and Their Antifungal Effects against Seed-Borne Fungi

“…For example, phenolics and terpenoids released by roots can show strong external antibacterial and antifungal activies . More recently, it has been demonstrated that small lipophilic molecules from the root exudates exhibited nematotoxic and/or repellent effects on Meloidogyne incognita and Myrmecina graminicola, suggesting that compounds of root exudates may have the potential for protecting plants against the damage of nematodes …”

Molecular Host-Nematode Interactions and Tuber Development

“…Sucrose, glucose, arabinose, galactose, and mannitol are chemo-attractants of Meloidogyne incognita, and signal transduction may involve Mi-odr-1, Mi-odr-3, Mi-tax-4 and Mi-tax-2genes [34][35][36]. Vanillic acid, lauric acid (signal transduction may require Mi-odr-1, Mi-odr-3, Mi-tax-2 and Mi-tax-4 genes) [34][35][36][37], arginine, lysine [34][35][36] and calcium chloride [35,38], Mi-odr-3, Mi-tax-2, Mi-tax-4 genes are chemotactic genes involve in Meloidogyne incognita and predicted functions are membrane-bound guanylyl cyclase that produces secondary messenger, α protein that regulates cyclic nucleotide metabolism, subunits of cyclic nucleotide-gated cation channel involved in G-protein-mediated signalling, respectively [35,36]. Carbon dioxide (CO2) is an important attractant released by roots for RKNs [39], and lauric acid controls the chemotaxis of root-knot nematodes [37].…”