Developmental and wound-, cold-, desiccation-, ultraviolet-B-stress-induced modulations in the expression of the petunia zinc finger transcription factor gene ZPT2-2

The ZPT2-2 gene belongs to the EPF gene family in petunia (Petunia hybrida) , which encodes proteins with TFIIIA-type zinc-finger DNA-binding motifs. T o elucidate a possible function for ZPT2-2, we analyzed its pattern of expr ession in relation to different developmental and physiological stress sign als. The activity of the ZPT2-2 promoter was analyzed using a firefly lucif erase (LUC) reporter gene, allowing for continuous measurements of transgen e activity in planta. We show that ZPT2-2::LUC is active in all plant tissu es, but is strongly modulated in cotyledons upon germination, in leaves in response to desiccation, cold treatment, wounding, or ultraviolet-B light, and in petal tissue in response to pollination of the stigma. Analysis of m RNA levels indicated that the modulations in ZPT2-2::LUC expression reflect modulations in endogenous ZPT2-2 gene expression. The change in ZPT2-2::LU C activity by cold treatment, wounding, desiccation, and ultraviolet-B ligh t suggest that the phytohormones ethylene and jasmonic acid are involved in regulating the expression of ZPT2-2. Although upregulation of expression o f ZPT2-2 can be blocked by inhibitors of ethylene perception, expression in plants is not induced by exogenously applied ethylene. The application of jasmonic acid does result in an up-regulation of gene activity and, thus, Z PT2-2 may play a role in the realization of the jasmonic acid hormonal resp onses in petunia.