Wound-induced expression of the FAD7 gene is mediated by different regulatory domains of its promoter in leaves/stems and roots

The FAD7 gene is expressed preferentially in the chlorophyllous tissues of unwounded plants. Wounding activates the expression of the FAD; gene not on ly in chlorophyllous tissues, but also in nonchlorophyllous tissues of stem s and roots. Our previous study suggested that wound-responsive transcripti onal activation by the FAD7 promoter in leaves/stems and roots is brought a bout by a jasmonic acid (JA)-independent and JA-dependent signaling pathway , respectively. In this paper, we show that a specific region (from -259 to -198) in the FAD7 promoter is required for wound-activated expression of t his gene in leaves and stems, while another region (from -521 to -363) is n ecessary not only for wound-activated but also for JA-responsive expression of this gene in roots. Thus, different regulatory regions of the FAD7 prom oter mediate distinct wound-induced expression of this gene in leaves/stems and roots. Gel mobility shift assays revealed the wound-inducible DNA-bind ing activity to the -242/-223 region in both stem and leaf nuclear extracts . In fact, deletion of this region abolished wound response of the FAD7 pro moter, suggesting the in vivo role of this site. Furthermore, we detected r oot nuclear factors interacting with the region from -433 to -363 of this p romoter. Wounding and methyl jasmonate treatments induced differently these DNA-binding activities. These results suggest that different regulatory me chanisms mediate the wound-induced expression of the FAD7 gene in aerial an d subterranean organs.