The potato cyst nematode Globodera pallida possesses an expanded serotonergic nervous system

The potato cyst nematode Globodera pallida exhibits a sophisticated serotonergic nervous system, according to recent research. Serotonin, a neurotransmitter, plays a crucial role in the parasitic lifestyle of plant parasitic nematodes. By employing serotonin immunochemistry and in situ hybridization for serotonin synthesis genes, Gpa-tph-1 and Gpa-bas-1, scientists mapped the serotonin signaling pathways in G. pallida J2 infective stages.

They discovered fourteen serotonin-immunoreactive cell bodies around the pharyngeal median bulb, with eleven of them expressing both Gpa-tph-1 and Gpa-bas-1, confirming their status as serotonin-synthesizing neurons. Moreover, serotonin immunoreactivity was found in structures likely labeling amphids and sixteen non-neuronal cells in the middle and posterior regions of the nematode.

When serotonin was depleted using reserpine, it reduced immunoreactivity in all fourteen cell bodies, confirming their neuronal identity, but not in non-neuronal tissue. Interestingly, additional, albeit infrequent, expressions of Gpa-tph-1 were identified in two cells, and Gpa-bas-1 in one pair of symmetrically bilateral cells anterior to the median bulb, which lacked serotonin immunoreactivity.

These findings suggest a more complex serotonin signaling system in G. pallida compared to other parasitic nematodes and C. elegans, emphasizing evolutionary divergence in neurotransmitter identity.