Transcriptional Regulation of Senescence-Related Genes in Carnation Flowers

Abstract

The senescence of flower petals in several plant species is associated with a dramatic increase in the production of ethylene. There is considerable evidence pointing to a role for this increased ethylene in regulating the processes of programmed cell death leading to senescence [13]. A number of years ago we reported that the senescence of carnation flower petals was associated with the expression of new genes, which led us to isolate a number of senescence-related cDNA clones that have been useful in elucidating the mechanism by which ethylene regulates their transcription [13]. In addition to its influence on the cell death program leading to floral senescence [27] ethylene controls the expression of genes during tomato fruit ripening [3,15] and pathogen attack [9,18,23]. Ethylene-responsive elements in the promoter regions of several genes have been identified [2,5,11,20]. While nuclear factors have been shown to specifically interact with some of these regulatory regions [5,11,20], little is known about the nature of these DNA binding proteins. Recently, Ohme-Takagi and Shinshi [23] have demonstrated that an 11-bp GCC box, conserved in the promoter regions of ethylene-regulated pathogenesis-related proteins, is sufficient for conferring ethylene-responsiveness to a heterologous promoter. Four different cDNAs encoding DNA binding proteins capable of interacting with the GCC box were cloned (EREBP-1 to 4). The DNA binding domain of the EREBPs does not share homology with other known DNA binding proteins.