Dissecting gene metabolite relationships in the Medicago truncatula terpenome after Aphanomyces euteiches infection

Abstract

Sesquiterpenes produced by terpene synthases (TPS) play key roles in plant defense. In Medicago truncatula, MtTPS10 was previously the only TPS linked to resistance against the root pathogen Aphanomyces euteiches, and its induction appears to be triggered by an A. euteiches elicitor (elicitor M) acting as a PAMP. Transcriptomic and metabolomic analyses revealed M. truncatula ecotype-specific defense strategies: Jemalong A17 expresses MtTPS10, while ecotype 368 expresses MITPS25 following pathogen contact. MtTPS25 encodes a root-specific sesquiterpene synthase that produces α-copaene as the main volatile, a role confirmed by RNAi silencing. Engineering potato plants with MtTPS enhanced resistance to Phytophthora infestans. Additionally, the cytochrome P450 CYP71D62 was identified as a candidate gene modifying the MtTPS10 sesquiterpene product, himachalol in planta. Together, these findings highlight the importance of terpene-mediated defenses in legumes and their potential for crop protection.