Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


A number of plant pathogenic bacteria has been shown to be highly sensitive to SB-37, a derivative of cecropin B (one of the three cecropins from the giant silk moth Hyalophora cecropia). The lytic activity exhibited by SB-37 has been shown to increase up to twenty-fold in the presence of chicken egg white lysozyme. The cDNAs genes encoding SB-37, attacin E (another component of the humoral response of Hyalophora cecropia), and chicken lysozyme have been introduced into tobacco (var Xanthi) and potato (a new cultivar 86007) plants by Agrobacterium-mediated transformation using co-integrate and binary vectors. The genes were placed under the control of different promotors: CaMV35S, Double-CaMV35S and the proteinase inhibitor II promoter from potato. The transformation of at least five independent lines for each construct has been confirmed by Southern blot and segregation analysis. Protein analysis demonstrated that the chicken egg white lysozyme was expressed in tobacco plants. Western analysis of Attacin E-transformed plants, failed to show expression of the gene at the protein level. Protein blot analysis of SB-37 transgenic lines gave unconclusive results indicating at least very low level of expression. When these plants were inoculated with P. solanacearum, at least two independent lines, showed symptoms earlier than control plants indicating some biological effect. The significance of this result is discussed in detail. Also, the characterization of different de novo designed peptides is described.