Quinone oxidoreductase 2 is involved in haustorium development of the parasitic plant Phtheirospermum japonicum

The family Orobanchaceae includes many parasitic plant species. Parasitic plants invade host vascular tissues and form organs called haustoria, which are used to obtain water and nutrients. Haustorium formation is initiated by host-derived chemicals including quinones and flavonoids. Two types of quinone oxidoreductase (QR) are involved in signal transduction leading to haustorium formation; QR1 mediates single-electron transfers and QR2 mediates 2-electron transfers. In the facultative parasite Triphysaria versicolor, QR1 is involved in haustorium induction signaling, while this role is played by QR2 in the model plant Phtheirospermum japonicum. Our results suggest that there is functional diversification in haustorium signaling molecules among different species of the Orobanchaceae.