Insecticidal activity of transgenic potato, (Solanum tuberosum L.) expressing avidin from chicken (Gallus gallus L.)

Colorado potato beetle, Leptinotarsa decemlineata (Say), and potato tuberworm, Phthorimaea operculella (Zeller), are destructive pests of potato, Solanum tuberosum L. Avidin is derived from chicken (Gallus gallus L.) that has demonstrated insecticidal activity to a broad spectrum of pests.; The potential for avidin as an insecticidal transgene was evaluated against Colorado potato beetle. The LC50 for avidin was determined to be 136 mug/ml (108-188). We sought to enhance resistance by combining avidin with natural host plant resistance derived S. chacoense.; Avidin was expressed in two potato lines: MSE149-5Y, a susceptible line, and ND5873-15, a S. chacoense-derived resistant line. The putative transformants were screened with PCR to validate insertion, Southern analysis to determine copy number, and ELISA to quantify avidin expression. The copy number ranged from 1--3. Avidin expression ranged from 0.0--64.5 muM +/- 0.3 S.E. Fourteen transgenic MSE149-5Y lines and 7 transgenic ND5873-15 lines were screened for Colorado potato beetle resistance. In general, larvae fed on transgenic avidin plants were significantly smaller and had significantly less survivors than the non-transgenic parental line at 3 d.; Insect resistance was further analyzed for four lines: MSE149-5Y (susceptible line), MSE75.7 (avidin line), ND5873-15 (S. chacoense-derived resistance), and ND75.3 (avidin + S. chacoense). Survival and was significantly less for Colorado potato beetle larvae fed on MSE75.7 or ND75.3 compared to MSE149-5Y or ND5873-15.; The development for Colorado potato beetle larvae was monitored over 56 d. Development from first to pre-pupal stage was significantly prolonged for larvae fed on MSE75.7 compared to larvae fed on MSE149-5Y. Significantly fewer larvae survived to adults fed on MSE75.7 or ND75.3 compared to larvae fed on MSE149-5Y or ND5873-15.; The development for potato tuberworm larvae was monitored over 28 d. Mortality of potato tuberworm larvae fed on the MSE149-5Y did not differ significantly from the mortality of larvae fed on the MSE75.7 or ND5873-15. Mortality (98% +/- 9 S.E.) of larvae fed on ND75.3 was significantly higher than larvae fed on MSE149-5Y.; Avidin-based resistance, alone or in combination with other natural or engineered host plant resistance factors, may be a useful in managing insect pests.