REGENERATION OF POPULUS-NIGRA TRANSGENIC PLANTS EXPRESSING A KUNITZ PROTEINASE-INHIBITOR (KTI3) GENE

Transgenic poplar (Populus nigra, cv. Jean Pourtet) plants were recove red as a result of Agrobacterium tumefaciens-mediated transformation p erformed with EHA105 pBI-KUN strain. Plasmid pBI-KUN contains a 650 bp insert derived from the soybean (Glycine max L.) KTi3, gene, coding f or a Kunitz trypsin proteinase inhibitor. A total of 58 independent tr ansgenic lines were obtained from 200 co-cultivated leaf explants. Sou thern blot hybridization analysis demonstrated the presence of KTi3 ge ne in the poplar genome. Northern blot analysis of different kanamycin -resistant plantlets confirmed the accumulation of KTi3 mRNA and revea led different levels of expression. The trypsin inhibitory activity wa s determined in poplar transgenic tissues by means of specific assay. Moreover, the trypsin-like digestive proteinases of the polyphagous mo th Lymantria dispar (Lepidoptera, Lymantriidae) and Clostera anastomos is (Lepidoptera, Notodontidae) were detected and inhibited in vitro by Kunitz proteinase inhibitor from selected transgenic plants. Two inse ct bioassays were performed on P. nigra transgenic plant lines, using larvae of the above mentioned insects. In both cases larval mortality and growth as well as pupal weight were not significantly affected whe n the insects were fed on transgenic leaves and control leaves, respec tively.