Abstract: Pinellia pedatisecta Agglutinin（PPA）belonging to mannose-binding lectin muti-family has insect resistant activity. A new gene,named PPA2,encoding a PPA protein was cloned by RT-PCR from young leaves of pinellia pedatisecta. The PPA2 consists of an ORF of 408 bp coding 135 amino acids（14.7 kD）,and contains a mannose conservative domain with three mannose-binding sites. The transgenic tobacco plants mediated by Agrobacterium with leaf disc method were obtained under the control of CaMV 35S promoter and Arabidopsis thaliana phloem promoter AtPP2. A few of homozygotic transgenic plants with single copy insertion and high expression level were indentified in T3 generation,and then these plants were divided into high,middle,and low classes according to the level of expression protein detected by western-blot analysis. The results of aphid bioassay showed that all transgenic plants had obviously insecticidal activity against the tobacco aphids（Myzus nicotianae）,and the CaMV 35S-PPA2 transgenic plants had the highest insecticidal activity,while the aphid inhibition was much lower in AtPP2-PPA2 transgenic plants than in CaMV 35S-PPA2 ones. These findings suggest that PPA2 is a suitable candidate gene for high efficient aphid resistance and has important application prospect.

Key words: Pinellia pedatisecta Agglutinin（PPA）, gene cloning, transgenic tobacco, aphid-resistant gene