Handrick, VinzenzVinzenzHandrickRobert, Christelle Aurélie MaudChristelle Aurélie MaudRobertAhern, Kevin RKevin RAhernZhou, ShaoqunShaoqunZhouRuiz Machado, Ricardo AlbertoRicardo AlbertoRuiz MachadoMaag, DanielDanielMaagGlauser, GaétanGaétanGlauserFernandez-Penny, Felix E.Felix E.Fernandez-PennyChandran, Jima N.Jima N.ChandranRodgers-Melnick, EliEliRodgers-MelnickSchneider, BerndBerndSchneiderBuckler, Edward S.Edward S.BucklerBoland, WilhelmWilhelmBolandGershenzon, JonathanJonathanGershenzonJander, GeorgGeorgJanderErb, MatthiasMatthiasErb0000-0002-4446-9834Köllner, Tobias GTobias GKöllner2024-10-242024-10-242016-07https://boris-portal.unibe.ch/handle/20.500.12422/144648Benzoxazinoids are important defense compounds in grasses. Here, we investigated the biosynthesis and biological roles of the 8-O-methylated benzoxazinoids, DIM2BOA-Glc and HDM2BOA-Glc. Using quantitative trait locus mapping and heterologous expression, we identified a 2-oxoglutarate-dependent dioxygenase (BX13) that catalyzes the conversion of DIMBOA-Glc into a new benzoxazinoid intermediate (TRIMBOA-Glc) by an uncommon reaction involving a hydroxylation and a likely ortho-rearrangement of a methoxy group. TRIMBOA-Glc is then converted to DIM2BOA-Glc by a previously described O-methyltransferase BX7. Furthermore, we identified an O-methyltransferase (BX14) that converts DIM2BOA-Glc to HDM2BOA-Glc. The role of these enzymes in vivo was demonstrated by characterizing recombinant inbred lines, including Oh43, which has a point mutation in the start codon of Bx13 and lacks both DIM2BOA-Glc and HDM2BOA-Glc, and Il14H, which has an inactive Bx14 allele and lacks HDM2BOA-Glc in leaves. Experiments with near-isogenic maize lines derived from crosses between B73 and Oh43 revealed that the absence of DIM2BOA-Glc and HDM2BOA-Glc does not alter the constitutive accumulation or deglucosylation of other benzoxazinoids. The growth of various chewing herbivores was not significantly affected by the absence of BX13-dependent metabolites, while aphid performance increased, suggesting that DIM2BOA-Glc and/or HDM2BOA-Glc provide specific protection against phloem feeding insects.en500 - Science::580 - Plants (Botany)article10.7892/boris.877032731767510.1105/tpc.16.00065