The peroxidase OcPOD10 promotes the parasitism of sunflower broomrape (Orobanche cumana) via mediating Reactive Oxygen Species (ROS) accumulation.

Orobanche cumana Wallr. is an obligate root parasite that mainly infects sunflower (Helianthus annuus L.), causing significant yield losses. Peroxidases are known to be involved in plant responses to abiotic and biotic stresses, while its role during parasitism has not been elucidated. This study investigated the role of OcPOD10, a peroxidase encoding gene from O. cumana, in the parasitic interaction between sunflower and O. cumana. OcPOD10 was specifically expressed in haustorium, an interface between sunflower root and O. cumana. Overexpression of OcPOD10 promoted parasite attachment, whereas silencing of OcPOD10 reduced broomrape attachment and induced haustorium necrosis. Exogenous application of peroxidase inhibitors resulted in a phenotype consistent with that of OcPOD10-silenced plants. Further mechanistic analysis revealed that silencing of OcPOD10 led to excessive ROS accumulation at the O. cumana infection site, subsequently triggering haustorium necrosis. These findings indicate that OcPOD10 acts as a positive regulator in O. cumana parasitism, maintaining haustorium integrity by scavenging ROS and thereby facilitating parasitism on sunflowers. Our study not only provides new insights into ROS-mediated parasitic mechanism but also offers a theoretical basis and potential target for breeding sunflower varieties resistant to O. cumana through the strategies such as host-induced gene silencing (HIGS) of OcPOD10.