Main conclusionExpression levels ofAtPP2-A3andAtPP2-A8are reduced in syncytia induced byHeterodera schachtiiand decline of their expression levels decreases host susceptibility, whereas their overexpression promotes susceptibility to parasite.AbstractPlant-parasitic nematodes cause huge crop losses worldwide.Heterodera schachtiiis a sedentary cyst-forming nematode that induces a feeding site called a syncytium via the delivery of secreted chemical substances (effectors) to host cells, which modulate host genes expression and phytohormone regulation patterns. Genes encoding the Nictaba-related lectin domain have been found among the plant genes with downregulated expression during the development of syncytia induced byH. schachtiiinArabidopsis thalianaroots. To investigate the role of two selected Nictaba-related genes in the plant response to beet cyst nematode parasitism, mutants and plants overexpressingAtPP2-A3orAtPP2-A8were infected, and promoter activity and protein localization were analyzed. In wild-type plants,AtPP2-A3andAtPP2-A8were expressed only in roots, especially in the cortex and rhizodermis. After nematode infection, their expression was switched off in regions surrounding a developing syncytium. Astonishingly, plants overexpressingAtPP2-A3orAtPP2-A8were more susceptible to nematode infection than wild-type plants, whereas mutants were less susceptible. Based on these results and changes inAtPP2-A3andAtPP2-A8expression patterns after treatments with different stress phytohormones, we postulate that theAtPP2-A3andAtPP2-A8genes play important roles in the defense response to beet cyst nematode infection.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00425-023-04196-y.