Abstract: Posttranslational modification of histones, in particular acetylation and deacetylation are involved in the regulation of gene expression. Histone deacetylases remove acetyl groups from histone proteins. The present invention is directed to a method of regulating gene expression in a transgenic plant comprising, introducing into a plant a first chimeric nucleotide sequence comprising a first regulatory element in operative association with a coding sequence of interest, and an upstream activating sequence, and a second chimeric nucleotide sequence comprising a second regulatory element in operative association with a nucleotide sequence encoding histone deaceytlase and a nucleotide sequence encoding a DNA binding protein, and growing the transgenic plant.

Abstract: A mitogen-activated protein (MAP) kinase kinase gene, tMEK2, was isolated from tomato cv. Bonny Best. By mutagenesis, a permanently-active variant, tMEK2MUT, was created. Both wild type tMEK2 and mutant tMEK2MUT were driven by a strong constitutive promoter, tCUP&Dgr;, in a tomato protoplast transient expression system. Pathogenesis-related genes, PR1b1 and PR3, and a wound-inducible gene, ER5, were activated by tMEK2MUT expression revealing the convergence of the signal transduction pathways for pathogen attack and mechanical stress at the level of MAPKK. Activation of biotic and abiotic stress response genes downstream of tMEK2 occurred through divergent pathways involving at least two classes of mitogen-activated protein kinase. This study shows that tMEK2 may play an important role in the interaction of signal transduction pathways that mediate responses to both biotic (eg disease) and abiotic (wound responsiveness) stresses.