Dirigent (DIR) proteins mediate regio- and stereo-specific monolignol coupling allowing formation of lignans, the ubiquitous and structurally diverse compounds involved in plant defence as antioxidants or biocides. In Arabidopsis, the DIR family consists of 25 members, but for most of them, their physiological functions remain unknown. DIR5 and DIR6 participate in (-)-pinoresinol biosynthesis1 and DIR12/DP1 is specific to the outer seed coat and essential for neolignans biosynthesis2. ESB1/DIR10, crucial for Casparian strip (CS) positioning, and DIR9, DIR16, DIR21, and DIR24 (DIR-e subfamily) were shown to be responsible for the majority of lignin deposition during CS formation3, 4. DIR13 (At4G11190) is the closest paralog of DIR5, DIR6, DIR12 and DIR14, but lacks the conserved residues necessary for (-)-pinoresinol formation and exhibits strong, although not exclusive, expression in the root1. DIR genes are induced by biotic and abiotic stresses5 and overexpression of some DIRs can lead to improved tolerance to biotic and abiotic stresses.