Characterization of the promoter of the Wiv-1 (Lin6) gene encoding a wound-inducible cell wall-bound acid invertase in tomato

Abstract

Fragments of different length (4 kb and 1 kb) of the 5′ upstream region of the Wiv-1 (Lin6) gene encoding a wound-inducible cell wall-bound acid invertase in tomato were fused to the beta-glucuronidase (GUS) gene and expressed in tobacco and tomato plants. The GUS activity detected was similar in all transformed lines, suggesting that the 1 kb region contains most of the regulatory motifs responsible for the characteristics of the Wiv-1 promoter. GUS activity was observed in vascular tissues of transgenic tomato and tobacco. In stem sections of transgenic tobaccos, the strongest activity was observed in the internal phloem of the nodes adjacent to the bases of petioles. The GUS activity in leaves of transgenic tobacco was elevated by addition of soluble sugars, especially sucrose. Previous studies suggested that the Wiv-1 enzyme participated in the regulation of carbohydrate contents in tomato leaves (Ohyama and Hirai 1999). The results obtained in the present study suggest that the Wiv-1 enzyme controls the loading of sucrose at the phloem of nodes and Wiv-1 regulation depends on the concentration of sugars in source leaves. Copyright © 2006 The Japanese Society for Plant Cell and Molecular Biology.