Wound-regulation and tissue specificity of the tomato prosystemin promoterin transgenic tobacco plants

To investigate whether the systemic defense signaling pathway in tobacco (N icotiana tabacum) plants may be regulated by a polypeptide signal related t o tomato prosystemin, tobacco plants were transformed with a chimeric gene consisting of a 2200 bp fragment containing the promoter region of the toma to prosystemin gene fused to the beta-glucuronidase coding region. Histoche mical and enzymatic assays demonstrated a low constitutive expression of th e reporter gene and a wound- and methyl jasmonate induction of the gene spe cifically in the vascular bundles of leaves and petioles. Synthesis of the prosystemin-GUS fusion protein in the vascular bundle, regulated by woundin g and methyl jasmonate, is similar to the synthesis of prosystemin in tomat o plants, from which the promoter was obtained. Although a prosystemin prot ein or mRNA has not been identified in tobacco using Northern and Western b lotting with tomato prosystemin cDNA or antibodies, the transcriptional ele ments necessary to recognize the tomato prosystemin promoter to express met hyl jasmonate-inducibility and tissue specificity are present in tobacco va scular bundle cells. This suggests that an analog related to tomato prosyst emin gene may be present in tobacco leaves that is regulated in the same ma nner as the tomato prosystemin gene. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.