XVI International Botanical Congess
Bt toxins are a family of bacterial proteins with specific insecticidal activity. Unfortunately, the mRNA of Bt toxin genes fail to reach levels in transgenic plants that are necessary for protection against insect pests. Synthetic genes have been used to circumvent this problem, however, the reason why the wild-type mRNA fails to accumulate was not well understood until recently. We have found that sequences in the coding region of a cryIA(c) Bt toxin gene mediate the rapid turnover and premature polyadenylation of the mRNA in plant cells. Further experiments analyzing Bt poly(A) sites and poly(A) signals from several plant genes indicate tobacco has more stringent requirements for the utilization of poly(A) signals than maize. This difference likely represents a dicot/monocot difference that is relevant to transgene design.