Study On Transgenic Tobacco Expressing Xbpi-1Gene Encoded A Protease Inhibitor Against Myzus Persicae Sulzer

Protease inhibitor can reduce the damage of pest by inhibiting the activty of insect protease.Study demonstrates the Xbpi-1(protease inhibitor from Xenorhabdus bovienii) had adverse effects onaphids, such as green peach aphid (Myzus persicae). To study the resistantance of Xbpi-1againstaphids, the gene of Xbpi-1was transferred into tobacco. The transgene's integration, teanscription andexpression were identified. Insect-resistance and agronomic traits of transgenic plants were alsostudied.Key results:(1) Plant expression vectors, pCAMBIA2300-35S-Xbpigfp-Ocs with Xbpigfp gene andpCAMBIA2300-35S-gfp-Ocs with gfp gene, were constructed, which are harboring CaMV35Spromoter and OCS terminator. The vectors were verified by restriction analysis and sequencing,and introduced into Agrobacterium tumefaciens strain EHA105by freeze-thaw method.(2) The Xbpigfp gene integration was confirmed by PCR and Southern blot. The transcription wasverified by RT-PCR. The expression of Xbpigfp in tobacco was detected by ELISA and greenfluorescence protein (GFP) signal.(3) The PPO activity of transgenic tobacco and the leaf weights in transgenic line5184weredramatically increased, however other changes in agronomic traits of transgenic tobacco have notbeen observed.(4) The resistance of transgenic tobacco against aphids (M. persicae), and effects on the proteaseactivity in aphids were studied. The results showed that the mean adult weights and biomassproduced were reduced about33.7%and36.2%, respectively, when aphids fed on line PI3transgenic plants compared to those fed on control plants (wild type and plants expressed GFPonly) after two weeks and the protease activity of aphids were significantly reduced.