Interactions between venation pattern formation genes in Arabidopsis thaliana

*Address correspondence to: J. L. Micol, División de Genética and nstituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, 03202 Elche, Alicante, Spain. e-mail: [email protected] ABSTRACT Aiming to contribute to the understanding of the genetic mechanisms underlying venation pattern formation in the vegetative leaves of Arabidopsis thaliana, we have previously analyzed the natural variability of this trait and searched for venation pattern mutants with normally shaped leaves after chemical and insertional mutagenesis. The rarity of such mutants suggested that vein patterning and leaf morphogenesis might not be independent processes. To test this hypothesis, we have examined 97 abnormally shaped leaf mutants, each one belonging to a different complementation group, and found 2 whose venation patterns differed from that of the wild type. We have focused our attention on one of these mutants, rotunda1 (ron1), and in a recessive monogenic trait, hemivenata (hve), which was identified in an ecotype. Our study reveals that the Hve phenotype is pleiotropic, including an extremely simple venation pattern, increased stem branching, altered root waving, and low fertility. We have obtained double mutants involving mutations at several genes known to participate in vascular development, and/or auxin transport and perception. Linkage analysis has allowed us to assign the HVE gene to a 200 kb interval in the short arm of chromosome 2. Further genetic and molecular analyses are in progress to identify HVE among the available candidate genes.