Are strigolactones a key in plant-parasitic nematodes interactions? An intriguing question

Background and aims Plant parasitic nematodes (PPNs) are among the most important pests in agriculture. Chemical inputs are widely used for their control; however, the negative impact of these agrochemicals on environmental and human health is a current concern. Biological control and interventions on rhizosphere signaling are promising ecofriendly alternatives for managing these pests in the field. Nevertheless, the molecular mechanisms involved in plant-PPN interaction need to be unraveled in order to develop appropriate management strategies. Strigolactones (SLs) are phytohormones that are exuded from roots, acting as signaling molecules in the rhizosphere. They are important cues in the establishment of arbuscular mycorrhizal and Rhizobium-legume symbioses. Recently, it has been shown that SLs can also affect the interaction between plants and certain PPN species; however, data are scarce and ambiguous. Some studies propose that SLs positively regulate PPN species performance acting as attractants to roots, or by inhibiting plant defense responses. On the contrary, other studies suggest that SLs could negatively regulate PPN performance by reducing abscisic acid, or by promoting plant interactions with beneficial soil microorganisms. In the present Opinion paper, we discuss these controversial results and propose future research challenges to develop new management strategies against these harmful PPN species.