R.J. Rukarwa, S.B. Mukasa, G. Ssemakula
School of Agricultural Sciences, Makerere University, P.O. Box 7062 Kampala, Uganda
National Crop Resources Research Institute, Namulonge, P.O. Box 7084, Uganda
Key words: Transgene, phenotypic characters, weevil resistance.
In this study, transgenic event, CIP410008.7 was used as donor parent of cry7Aa1 gene and a commercial cultivar, New Kawogo, was used as the recipient parent. A total 53 progenies were obtained and evaluated. The characters evaluated were vine vigour, vine internode length, vine length, foliage weight, root skin and flesh colour, carotenoid content, number of storage roots and weevil resistance. Significant variation in vine vigour, vine length, number of roots per plant and carotenoid content (p<0.05) was observed in the F1 progeny. However, no significant differences were observed for foliage weight and vine internode length. The existence of continuous variation of the measured traits indicated the quantitative nature of most sweetpotato traits. The progenies were also analysed for the presence of cry7Aa1 using PCR. Expected 608bp bands were amplified in progenies that contained cry7Aa1. Chi-square test showed a 1:1 segregation ratio. There was no significant difference in production of roots between the transgenic and non transgenic segregants, showing that the transgenic plants were not affected by the presence of cry7Aa1. In insect bioassays, there were significant differences in the mean development period of the weevil (p=0.03), total number emerged (p<0.001) and susceptibility index (P<0.001) between the transgenic progeny and control sweetpotato roots.