Plays a role in the differentiation or division of feeding cells (syncytia) induced in plant roots during infection. Promotes host root growth. Secreted into host root cells via the nematode stylet to transform the recipient cells into enlarged multinucleate feeding cells called giant-cells or syncytia. Highly expressed exclusively within the subventral esophageal gland cell during syncytium formation in host plants. Belongs to the CLV3/ESR signal peptide family.