Interactions between INCURVATA genes in Arabidopsis thaliana

One of the most frequently represented phenotypic classes among the leaf mo rphological mutants available in Arabidopsis thaliana is that named Incurva ta (Icu), whose members display curled, involute leaves. Here we describe e thyl methanesulfonate-induced alleles of the INCURVATA9 (ICU9) gene, which cause several leaf abnormalities, such as organ radialization and the prese nce of abaxial trichomes in juvenile leaves. These morphological aberration s can be interpreted as a consequence of a partial transformation of ventra l into dorsal leaf identity, which makes the ICU9 gene a candidate for bein g involved in the specification and/or maintenance of leaf dorsoventrality. In order to identify genetic operations at work during leaf morphogenesis, we have obtained double mutants involving alleles of ten ICU loci, finding that ICU9is functionally related to other five ICU genes. All these six ge nes seem to be essential for the leaf to properly develop.