Broomrape-host interaction: host morphology and physiology as metrics for infestation

In contrast to other plant pests, broomrape, parasitic plant, rely on maintaining the productivity of the host plant to complete their life cycle. Parasitic plants, particularly those in the Orobanchaceae family, rely on their host plants to complete their life cycle. Unlike other plant parasites such as fungi and bacteria, which exploit their hosts regardless of their physiological status, parasitic plants development is linked to the host productivity due to their mutual physiological dependence on water availability and sugar metabolism. Presently, most research focuses on the damage caused to the host after the parasite completes its life cycle, including inflorescence emergence and seed dispersal. However, the interaction between parasite and host begins long before these stages. This implies that certain physiological adaptations are necessary to sustain the parasite's development while maintaining the host's productivity. In this review, I compile existing knowledge regarding changes in host physiology during the early developmental stages of parasitic plants, spanning from attachment to inflorescence emergence. Additionally, I highlight knowledge gaps that should be addressed to understand how hosts sustain themselves throughout extended periods of parasitism.