Sustainable management of root-knot nematodes in horticultural crops by modeling and optimizing resistance gene deployment

Root-knot nematodes (RKNs) of the genus Meloidogyne are soil-borne, little mobile, polyphagous pests which threaten important sheltered crops such as vegetables or small fruits. They attack plant roots to feed and reproduce and have a major impact on crop yield. Most eco-friendly plant protection strategies are based on the use of resistant crops. Resistance is usually associated with a hypersensitivity reaction (HR), a rapid and localized cell death in the infected plant in response to a pathogenic attack. In the family Solanaceae, there are two major resistance genes (R genes) with different modes of action : an early HR when the nematode enters in the root system and a late HR when the nematode creates its feeding site. The emergence of virulent nematode variants, which are adapted to the resistance, challenges the durability of such methods. Because virulent root-knot nematodes exhibit a reduced fitness on susceptible crops, combining both resistant and susceptible plants can help increase the efficacy and sustainability of resistance-based nematode control. We carried out a preliminary study to investigate the best rotations of susceptible and resistant cultivars over cropping seasons in terms of yield and resistance durability. The resistance considered was associated with early HR. For this purpose, we developed a semi discrete model describing the plant root growth and nematode population dynamics within and between cropping season, including the plant nematode interactions. Our aim in this study is to implement and compare the action of both R genes. We will first compare the optimal deployment strategies of resistant crops for both R genes. Then we will determine the best rotations based on both resistant cultivars.