Abstract
Venation develops complex patterns within the leaves of angiosperms, and the mechanism of leaf vein patterning remains poorly understood. Here, we report a spontaneous mutant that exhibits yellow serrated leaves and defective cotyledon vein patterning. We mapped and cloned the relevant gene YELLOW, SERRATED LEAF (YSL), a previously unreported gene in plants. YSL interacts with VH1-interacting kinase (VIK), a protein that functions in cotyledon venation development. VIK is a vascular-specific adaptor protein kinase that interacts with another vascular developmental protein, VASCULAR HIGHWAY1 (VH1)/BRASSINOSTEROID INSENSITIVE 1-LIKE 2 (BRL2), which is a receptor-like kinase of the BRASSINOSTEROID INSENSITIVE 1 (BRI1) family. Mutation of YSL affects the auxin response and the expression of auxin-related genes in Arabidopsis (Arabidopsis thaliana). Our results reveal that YSL affects cotyledon vein patterning by interacting with VIK in Arabidopsis.