flp-32 Ligand/Receptor Silencing Phenocopy Faster Plant Pathogenic Nematodes

Abstract

Restrictions on nematicide usage underscore the need for novel control strategies for plant pathogenic nematodes such as Globodera pallida (potato cyst nematode) that impose a significant economic burden on plant cultivation activities. The nematode neuropeptide signalling system is an attractive resource for novel control targets as it plays a critical role in sensory and motor functions. The FMRFamide-like peptides (FLPs) form the largest and most diverse family of neuropeptides in invertebrates, and are structurally conserved across nematode species, highlighting the utility of the FLPergic system as a broad-spectrum control target. flp-32 is expressed widely across nematode species. This study investigates the role of flp-32 in G. pallida and shows that: (i) Gp-flp-32 encodes the peptide AMRNALVRFamide; (ii) Gp-flp-32 is expressed in the brain and ventral nerve cord of G. pallida; (iii) migration rate increases in Gp-flp-32-silenced worms; (iv) the ability of G. pallida to infect potato plant root systems is enhanced in Gp-flp-32-silenced worms; (v) a novel putative Gp-flp-32 receptor (Gp-flp-32R) is expressed in G. pallida; and, (vi) Gp-flp-32R-silenced worms also display an increase in migration rate. This work demonstrates that Gp-flp-32 plays an intrinsic role in the modulation of locomotory behaviour in G. pallida and putatively interacts with at least one novel G-protein coupled receptor (Gp-flp-32R). This is the first functional characterisation of a parasitic nematode FLP-GPCR.

Family of FLP Peptides in Caenorhabditis elegans and Related Nematodes

“…In a sand column motility assay, knockdown of Gp - flp-1 and 18 and flp-6, 12 , and 14 inhibited motility of second-stage juvenile (J2) Globodera pallida animals by 70–100% after 24 h of dsRNA soaking; the effects were transitory and by 6 days post-treatment, 27.1% of the animals recovered 39.4% of their normal activity ( 133 ). By contrast, when Gp - flp-32 was knocked down, G. pallida and Meloidogyne incognita juveniles became more mobile, which translated to an enhanced ability to infect potato plant and other plant roots ( 135 ).…”

Combinatorial in vitro RNAi of two neuropeptide genes and a pharyngeal gland gene on Meloidogyne incognita

“…Urwin et al (2002) demonstrated that octopamine, a neuro active stimulant, could stimulate the oral uptake of dsRNA. Following this approach, investigation of FLP gene function through RNAi has been well documented for some key plant-parasitic nematodes (Urwin et al, 2002;Kimber et al, 2007;Dalzell et al, 2009;Atkinson et al, 2013). In vitro RNAi silencing of the two neuropeptide genes, flp-12 and flp-18, reduced the migration of J2 of M. incognita in a sand column (Dalzell et al, 2010).…”

Targeting internal processes of plant-parasitic nematodes in the pursuit of novel agents for their control

“…One application of com parative genomic analysis has already revealed that the ge netic bases of developmental arrest in C. elegans and H. glycines differ significantly (Elling et al, 2007), provid ing important guidance for analysis of development. The area of nematode neuropeptides and their application for nematode control has flourished with a foundation in C. elegans genetics (Li, 2005;Li & Kim, 2010) and the co operation amongst those investigating the genetics, phys iology and biochemistry of these regulatory molecules in free-living, plant-parasitic and animal-parasitic nema todes (McVeigh et al, 2008(McVeigh et al, ,2012Holden-Dye & Walker, 2011;Maule & Curtis, 2011;Atkinson et al, 2013).…”