SYSTEMIC INDUCTION OF A POTATO PIN2 PROMOTER BY WOUNDING, METHYL JASMONATE, AND ABSCISIC-ACID IN TRANSGENIC RICE PLANTS

To address the question whether common signal(s) and transduction path ways are used to mediate a systemic wound response in monocot and dico t plants, a fusion of the potato proteinase inhibitor II gene (pin2) p romoter and the bacterial beta-glucuronidase gene (Gus)-coding region was introduced into rice. In transgenic rice plants, the expression of the pin2-Gus fusion gene displays a systemic wound response, although the expression level is relatively low. Incorporation of the first in tron from the rice actin 1 gene (Act1) into the 5'-untranslated region of the pin2-Gus construct results in high-level, systemically wound-i nducible expression of the modified construct in transgenic rice plant s. Histochemical analysis shows that this high-level, wound-inducible expression is associated with the vascular tissue in both leaves and r oots. Furthermore, the expression of the pin2-Act1 intron-Gus fusion g ene in transgenic rice plants can be systemically induced by both meth yl jasmonate (MJ) and the phytohormone abscisic acid (ABA). These resu lts suggest that the signal(s) mediating the observed systemic wound r esponse and certain steps of the transduction pathways are conserved b etween dicot and monocot plants. Transient expression assays show that the pin2-Act1 intron-Gus construct is also actively expressed in tran sformed cells and tissues of several other monocot plants. Thus, the w ound-inducible pin2 promoter in combination with the rice Act1 intron 1 might be used as an efficient regulator for foreign gene expression in transgenic monocot plants.