Transformation of white poplar (Populus alba L.) with a novel Arabidopsis thaliana cysteine proteinase inhibitor and analysis of insect pest resistance

Transgenic white poplar (Populus alba L.) plants expressing a novel Arabido psis thaliana cysteine proteinase inhibitor (Atcys) gene have been produced using Agrobacterium tumefaciens-mediated gene transfer. Internodal stem se gments of cv. Villafranca were co-cultivated wit the EHA105 pBI-Atcys A. tu mefaciens strain. Sixteen putative transgenic plant lines were regenerated from different calli with a transformation efficiency of 11%. The integrati on and expression of the cysteine proteinase inhibitor (Atcys) gene into th e plant genome was confirmed by Southern and northern blot analyses. Papain inhibitory activity was detected in poplar transgenic tissues by means of a specific in vitro assay. Such activity was sufficient to inhibit most of the digestive proteinase activity of chrysomelid beetle (Chrysomela populi L.) and confer resistance to C. populi larvae on selected transgenic plants . A close correspondence between the inhibition of papain and resistance to poplar leaf beetle was observed in all tested transgenic lines. Our result s indicate that Ateys could be succesfully employed in breeding programmes aimed at the selection of new poplar genotypes resistant to major insect pe sts.