Identification and characterisation of serotonin signalling in the potato cyst nematode Globodera pallida reveals new targets for crop protection

Abstract

Plant parasitic nematodes are microscopic pathogens that invade plant roots and cause extensive damage to crops. We have used a chemical biology approach to define mechanisms underpinning their parasitic behaviour: We discovered that reserpine, a plant alkaloid that inhibits the vesicular monoamine transporter (VMAT), potently impairs the ability of the potato cyst nematode Globodera pallida to enter the host plant root. We show this is due to an inhibition of serotonergic signalling that is essential for activation of the stylet which is used to access the host root. Prompted by this we identified core molecular components of G . pallida serotonin signalling encompassing the target of reserpine, VMAT; the synthetic enzyme for serotonin, tryptophan hydroxylase; the G protein coupled receptor SER-7 and the serotonin-gated chloride channel MOD-1. We cloned each of these molecular components and confirmed their functional identity by complementation of the corresponding C . elegans mutant thus mapping out serotonergic signalling in G . pallida . Complementary approaches testing the effect of chemical inhibitors of each of these signalling elements on discrete sub-behaviours required for parasitism and root invasion reinforce the critical role of serotonin. Thus, targeting the serotonin signalling pathway presents a promising new route to control plant parasitic nematodes.

Deficiency in RCAT-1 Function Causes Dopamine Metabolism Related Behavioral Disorders in Caenorhabditis elegans

“…This phenotype differed from the phenotypes of the wellknown dopamine metabolism-deficient mutants cat-1(ok411) and cat-2(e1112) (Figure 3A), which usually exhibit a lower turning frequency than N2 wild-type animals [7]. cat-1(ok411) and cat-2(e1112) are null mutants for the corresponding gene, like their other mutant alleles, cat-1(e1111) and cat-2(n4547) [12,[28][29][30]. Instead, the phenotype of R02D3.7(ok1745) mutants was similar to the phenotype seen after treatment with exogenous dopamine, which results in more frequent turning behavior (Figure 3B) [2].…”

Co-Silencing of the Voltage-Gated Calcium Channel β Subunit and High-Voltage Activated α1 Subunit by dsRNA Soaking Resulted in Enhanced Defects in Locomotion, Stylet Thrusting, Chemotaxis, Protein Secretion, and Reproduction in Ditylenchus destructor

“…The neurotransmitter serotonin is a conserved regulator of various behaviors in animals. The application of serotonin induces stylet thrusting in some plant-parasitic nematode species in the absence of a host [ 20 , 21 , 22 ]. To evaluate the effect of knockdown of the α 1 and β subunits on the stylet thrusting of D. destructor , dsRNA-treated nematodes were soaked in serotonin (5 mM/L) for 20 min and the frequency of stylet thrusting per minute was observed under a microscope.…”