Résumé
The 5' upstream region of two highly homologous hevein genes from rubber tree (PHev2.1 and PHev2.3) were isolated. Hevein is a small lectine-like protein pertaining to the group of type IV Pathogenesis-Related proteins. In rubber tree, it is located in latex cells exclusively and participates in the latex coagulation processes. It has antifungal properties in vitro. The 1.8 kb PHev2.1 promoter sequence fused to the GUS reporter gene was introduced in rice by Agrobacterium-mediated transformation. It appeared to be functional both in leaves, roots and anthers. It was activated in response to mechanical wounding in leaves, both directly and systemically, raising the promoter activity level close to that of the 35S promoter. Additionally, a 1.2 to 1.6 fold activation was observed after inoculation with the rice pathogen Magnaporthe grisea. These results are in agreement with the presence on the sequence of potential regulatory elements involving biotic and abiotic stress signal transduction hormones. The 0.9 kb PHev2.3 promoter sequence and derived deleted -fragments, fused to the GUS reporter gene, were introduced in rubber tree callus by Agrobacterium-mediated transformation. All fragments were functional, both in callus and embryoids. Tissue specificity as well as the response to biotic and abiotic stresses will be analyzed in the regenerated transgenic plants. The regulation properties observed confirm the expected role of hevein in defense. Moreover, the functionality of the hevein promoter both in dicots (rubber tree) and monocots (rice) opens the doors for a utilization in various homologous or heterologous systems, in genetic engineering programs aiming to increase the protection against biotic or abiotic stresses. (Texte intégral)