Understanding Orobanche and Phelipanche–host plant interactions and developing resistance

Orobanche and Phelipanche spp. (broomrapes) are parasitic plants that can be responsible for devastating losses in several important crops. The development of resistant cultivars is one of the key strategies in the fight against this pest. However, the nature of resistance is complex and the basis of the interaction between the host and the parasite is still largely unknown. Despite the progress achieved during the last century through breeding programmes, sources of resistance are often scarce (e.g. the legumes). The resistance that is available is often not durable, with field resistance being overcome by new races of the parasite (e.g. sunflower). This review summarises efforts made to improve the resistance of crop hosts for broomrapes through classical breeding programmes and looks forward to the integration of new knowledge generated from molecular and morphological studies. Emphasis is given to the need for a multidisciplinary approach to achieve success, ranging from improved field phenotyping to genetic and biotechnological studies. All components are necessary to understand this particular and characteristic interaction: a plant parasitising another plant.