Proceedings of the XLV Italian Society of Agricultural Genetics - SIGA Annual Congress

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

PHENOTYPIC AND MOLECULAR CHARACTERISATION OF ARABIDOPSIS THALIANA LINES EXPRESSING A MURINE INOS

EDERLE D., SBICEGO P.

Istituto di Botanica e Genetica Vegetale, Università Cattolica del S. Cuore, Piacenza

delledonne@pc.unicatt.it

nitric oxide, hypersensitive response, plant-pathogen interaction

Plants have evolved several mechanisms to prevent invasions of their tissues by pathogens. A common feature of disease resistance is the hypersensitive response (HR) occurring in the area surrounding the infection sites, which is characterised by the formation of necrotic lesions that block pathogen spreading in plant tissues. The activation of this response is mediated by recognition of pathogen elicitors by specific plant resistance gene products. This recognition leads to the production of both Reactive Oxygen Species (ROS) and Nitric Oxide (NO). It has been recently reported that the triggering of HR is mediated by the interaction between ROS and NO. Even if it is quite well known how plants produce ROS involved in this process, thus far it is still unknown which mechanism have evolved to generate NO. In fact NO could be produced not only by Nitric Oxide Synthases (NOS), as occur in animal immune systems, but also from several other sources like Nitrite Reductases, that produce NO as a by-product. However some data, obtained using animal NOS inhibitors, has suggested the presence of NOS also in plants and its activity has been reported especially in plant organelles like peroxisomes. Nevertheless this enzyme and its coding gene are still elusive. In this study, Agrobacterium-mediated transformation of Arabidopsis thaliana, using a murine iNOS (M84373) in absence of a known NOS plant gene, has been performed in order to investigate in plants the effect of endogenous overproduction of NO, even if, by now, is still unknown whether plants are able to produce a necessary cofactor for animal iNOS activity, the BH4 tetrabiopterin, or if, in plants, this enzyme could preserve its function without it. Several transgenic lines expressing the iNOS gene under control of the constitutive CaM35S were obtained, and also other lines presenting the gene under the inducible GVG promoter, in case of citotoxicity of this enzyme. Some lines were then selected for high levels of NOS expression with the constitutive promoter and also with the GVG promoter. Molecular and phenotypic analysis are in progress.