Expression levels of AtPP2-A3 and AtPP2-A8 are reduced in syncytia induced by Heterodera schachtii and decline of their expression levels decreases host susceptibility, whereas their overexpression promotes susceptibility to parasite. Plant-parasitic nematodes cause huge crop losses worldwide. Heterodera schachtii is 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 by H. schachtii in Arabidopsis thaliana roots. To investigate the role of two selected Nictaba-related genes in the plant response to beet
cyst nematode parasitism, mutants and plants overexpressing AtPP2-A3 or AtPP2-A8 were infected, and promoter activity and
protein localization were analyzed. In wild-type plants, AtPP2-A3 and AtPP2-A8 were 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 overexpressing AtPP2-A3 or AtPP2-A8 were more susceptible to
nematode infection than wild-type plants, whereas mutants were less susceptible. Based on these results and changes in AtPP2-A3 and AtPP2-A8 expression patterns
after treatments with different stress
phytohormones, we postulate that the AtPP2-A3 and AtPP2-A8 genes play important roles in the defense response to beet
cyst nematode infection.