Responses of Heterodera glycines and Meloidogyne incognita to exogenously applied biogenic amines

Abstract

Hatching and head movement behaviours of second-stage juvenile (J2) of two agriculturally important plant-parasitic nematodes were affected by the in vitro application of biogenic amines. The behavioural responses of Heterodera glycines and Meloidogyne incognita to treatments of serotonin, octopamine and dopamine were qualitatively similar, but significant quantitative differences between the species were revealed. The frequency of J2 head movement was decreased by as little as 250 μM serotonin in H. glycines and 500 μM serotonin in M. incognita, with effective doses (ED 50 ) of 0.73 mM for H. glycines and 1.72 mM for M. incognita. Octopamine had the opposite effect of serotonin, increasing J2 head movement frequency at thresholds of 2 mM in H. glycines and 1 mM in M. incognita. Octopamine ED 50 values were 32.35 mM and 1.91 mM, respectively. Dopamine had no effect on head movement in either species up to concentrations of 20 mM. Serotonin inhibited hatch in both species but was more potent against H. glycines (90% inhibition at 1 mM) than M. incognita (40% inhibition at 5 mM). Octopamine reduced hatch equally in both species with over 95% inhibition at 80 mM. Dopamine had no effect on hatch in M. incognita but did inhibit H. glycines hatch over 60% at 40 mM. The value of detailed quantitative analyses of plant-parasitic nematode responses to biogenic amines for studies on nematode control is discussed.

Comparative analysis of pre- and post-parasitic transcriptomes and mining pioneer effectors of Heterodera avenae

“…For instance, octopamine is used to stimulate ingestion of dsRNA in invitro RNAi experiments by increasing the pharyngeal pumping of plant nematodes [ 65 ]. On the other hand, since octopamine displays roles in inhibition of egg laying in C. elegans , investigators have adopted octopamine as an effect approach in the control of phytonematodes [ 66 , 67 ]. Our greater understanding of the available target molecules will considerably help in the rational design of new biological nematicide, as well as in the development of next-generation chemical nematicide with minimal adverse effects.…”

Elicitation of Differential Responses in the Root-Knot Nematode Meloidogyne incognita to Tomato Root Exudate Cytokinin, Flavonoids, and Alkaloids

“…This result is in agreement with a study where exogenously applied neuromodulators had differing effects on soybean cyst nematode, Heterodera glycines, and M. incognita J2 behavior. 23 For example, serotonin a known activator of stylet thrusting elicited a concentrationand time-dependent stylet thrusting, which reached a plateau at a high concentration. 23,24 Similarly, in the chemotaxis assays, attractiveness of J2s to the root exudate was concentrationdependent and significantly higher (77.2%; χ 2 = 26.1; df = 1; and p < 0.001) than the negative control.…”

“…23 For example, serotonin a known activator of stylet thrusting elicited a concentrationand time-dependent stylet thrusting, which reached a plateau at a high concentration. 23,24 Similarly, in the chemotaxis assays, attractiveness of J2s to the root exudate was concentrationdependent and significantly higher (77.2%; χ 2 = 26.1; df = 1; and p < 0.001) than the negative control. For instance, at 10 μg/g of sand, the attractiveness of the root exudate compared favorably to the positive control, MeSA, at 20 ng/g of sand (73.4%; χ 2 = 21.94; df = 1; and p < 0.001) (Figure 3B).…”

Neurobiology of plant parasitic nematodes

“…In a separate study using Heterodera schachtii, 5-HT, 10 mM, stimulated stylet thrusting and eversion of spicules and extrusion of materials from the reproductive tract of males (Jonz et al 2001). In a second study, Masler (2008) studied the effects of biogenic amines on hatching and head movement behaviours of J2 M. incognita and H. glycines. The frequency of head movement was reduced by high micromolar concentrations of 5-HT in both species with ED 50 values for M. incognita and H. glycines of 1.72 and 0.73 mM, respectively.…”