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Abstract

• Strigolactones (SLs) are carotenoid‐derived plant hormones that also act in the rhizosphere to stimulate germination of root‐parasitic plants and enhance plant symbiosis with beneficial microbes. Here, the role of SLs was investigated in the interaction of rice roots with the root‐knot nematode Meloidogyne graminicola.

•Genetic approaches and chemical sprays were used to manipulate SL signaling in rice prior to infection with M. graminicola. Then, nematode performance was evaluated and plant defense hormones were quantified.

•Meloidogyne graminicola infection induced SL biosynthesis and signaling and suppressed jasmonic acid (JA)‐based defense in rice roots suggesting a potential role of SLs during nematode infection. While the application of low dose of the SL analog GR24 increased nematode infection and decreased jasmonate accumulation, the SL biosynthesis and signaling d mutants were less susceptible to M. graminicola, and constitutively accumulated JA and JA‐isoleucine compared to wild‐type plants. Spraying with 0.1 μM GR24 restored nematode susceptibility in SL‐biosynthesis mutants but not in the signaling mutant. Furthermore, foliar application of the SL biosynthesis inhibitor TIS108 impeded nematode infection and increased jasmonate levels in rice roots.

•In conclusion, SL signaling in rice suppresses jasmonate accumulation and promotes root‐knot nematode infection.