Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Plant, Enviromental and Soil Sciences

First Advisor

William J. Blackmon


Tuber disks from four cultivars of Solanum tuberosum L. were cultured on a Murashige and Skoog medium supplemented with B5 vitamins, 3.0% sucrose, 0.7% phytagar and ratios of indole-3-actyl-aspartic acid (IAAa) and zeatin riboside (ZR). No shoots were regenerated from Red LaSoda. Russet Burbank, Desiree, and LaBelle tuber disks produced shoots over a range of IAAa and ZR ratios. The greatest number of shoots was regenerated from Russet Burbank at 1 $\mu$M IAAa and 8 $\mu$M ZR. Different potato cultivars were also tested for their responses to Agrobacterium infections. Growth stage of the bacterial cultures and exposure duration of tuber disks to bacteria did not have a significant effect. However, significant differences among the cultivars in their responses to infection from A. rhizogenes and A. tumefaciens strains were observed. When effects of lytic peptides SB-37 and Shiva-1 on growth of plant pathogenic fungi were tested, a complete inhibition was observed at 10$\sp{-3}$ M, whereas, a mild stimulation of growth was noted at 10$\sp{-5}$ M. The effect of SB-37 on tobacco-cell suspensions was also tested. Cell growth was inhibited at 10$\sp{-3}$ M and somewhat arrested at 10$\sp{-4}$ M. At 10$\sp{-6}$ M and 10$\sp{-7}$ M SB-37 growth of the cells was stimulated. Leaf disks from transgenic and nontransgenic tobacco (Nicotiana tabacum L.) plants were exposed to a disarmed A. tumefaciens containing genes in a binary vector arrangement with one set of constructs for antibacterial (lytic) peptides and with another set of constructs for high essential amino acids (HEAA) II. Positive beta-glucuronidase (GUS) activity indicated that transformation had been obtained for both transgenic and nontransgenic plants. Although GUS positive plants were obtained with A. tumefaciens carrying HEAA II, transgenic plants were not exposed to this vector. Kanamycin resistant shoots regenerated from Russet Burbank tuber disks infected with binary A. tumefaciens vectors carrying antibacterial and HEAA II genes were also obtained.