Ectopic expression of the Arabidopsis AtMYB23 gene induces differentiationof trichome cells

The control of epidermal cell fate is a complex molecular process and requi res the regulatory activity of different transcription factors. Here, we de scribe the isolation of a member of the Arabidopsis MYB transcription facto r family, AtMYB23, that is involved in trichome development. Expression of the AtMYB23 gene under the control of the viral CaMV 35S promoter causes th e development of ectopic trichomes, The formation of ectopic trichomes depe nds on TRANSPARENT TESTA GLABRA1 but not on GLABRA1, The absence of the neg ative regulator TRIPTYCHON leads to branching of the ectopic trichomes on c otyledons and the formation of ectopic trichomes in the leaf subepidermal c ell layer. The CaMV 35S promoter-controlled expression of AtMYB23 can parti ally rescue the glabra1 mutant phenotype, Together, the presented data indi cate that the AtMYB23 gene has partially overlapping functions with GLABRA1 in controlling the initiation of trichome development. (C) 2001 Academic P ress.