Identification of Expression of CpTI Gene in Transgenic Poplars at Protein Level

The contents of total soluble protein and cowpea trypsin inhibitor (CpTI)in the browse and metaphylla of transgenic hybrid triploid poplars(Populus tomentosa×P. bolleana)×P. tomentosa transformed with CpTI gene were determined in order to study the products of CpTI gene expression at protein level. The results indicated that the amount of total soluble protein was greater in transgenic poplars than in non-transgenic poplars, but was more in the metaphylla than in browse. The expression of CpTI gene resulted in an obvious increase in CpTI content, whereas CpTI was not detected in non-transgenic poplars.It was found that there were high amount of total soluble protein and CpTI in 3 clones of TG07, TG04 and TG71 compared with other transgenic clones. In addition, the analysis of protein by SDS-PAGE showed that a specific protein band of about 11.3 kD corresponding to the 80 amino acids encoded by the CpTI gene was observed in transgenic poplars on the gel of protein, which was not detected in non-transgenic poplars.