The assembly of a syncytium, a multi-nucleate and physiologically active aggregation of fused root cells induced by a symbiotic nematode in a plant host. The syncytium exclusively provides the nematode with nourishment during its sedentary life, for the purpose of obtaining nutrients from its host organism. The host is defined as the larger of the organisms involved in a symbiotic interaction.
formation by symbiont of syncytium involving giant cell for nutrient acquisition from host