Secreted venom allergen-like proteins of plant-parasitic nematodes modulate defence responses in host plants

The venom allergen-like proteins form a family of effectors that seems to be conserved among all parasitic nematodes of plants and animals studied to date. Recently, we have shown that the venom allergen-like protein of the potato cyst nematode Globodera rostochiensis Gr-VAP1 interacts with the apoplastic cysteine papain-like proteases Rcr3pim of Solanum pimpinellifolium. Gr-VAP1 and Rcr3pim are both required to activate defencerelated programmed cell death and resistance to nematodes mediated by the extracellular plant immune receptor Cf-2 in tomato. Thus, Gr-VAP1 is able to trigger defence responses in a host plant of G. rostochiensis, but the virulence function of Gr-VAP1 or of any other venom allergen-like protein of an animal- and plant-parasitic nematode is not known. A specific knock-down of Gr-VAP1 expression in G. rostochiensis showed that the effector is indeed important for virulence of infective juveniles in host plants. Similarly, the ectopic expression of venom allergen-like proteins in transgenic plants alters their response to nematodes and other plant pathogens. RNAseq analysis of these transgenic plants has shed light on the molecular mechanisms underlying the virulence function of venom allergen-like protein of plant-parasitic nematodes in plants.