Effects of potato plants expressing the nptII-gus fusion marker genes on reproduction, longevity, and host-finding of the peach-potato aphid, Myzus persicae

Transgenesis developed in the last 20 years offers new possibilities for crop protection. The transgenic process, however, requires the use of marker fusion genes to select and visualize the transformed tissues. Although the expression products of these marker genes are stably expressed in crops, little attention has been given to assess the eventual risks of these recombinant proteins on phytophage populations. Three independent transgenic potato ( Solanum tuberosum) clones from the cultivar Desiree ( DG5, DG18, and DG20) carrying the commonly used nptII-gus gene construct and exhibiting different beta-glucuronidase activity (0.843 +/- 0.011, 0.576 +/- 0.096, and 0.002 +/- 0.000 pmol min(-1).mg(-1), respectively) were evaluated to determine the impact of the encoded proteins on the behaviour, development, reproduction, and demography of the peach-potato aphid, Myzus persicae, under laboratory-controlled light and temperature. Our results revealed that the transgenic event can alter aphid physiology or behaviour. Experiments showed a probiotic effect of one transgenic line, the DG5, resulting in reduced prereproductive period and mortality, and enhanced daily fecundity, which was expressed in a greater population growth potential (r(m) = 0.205 vs. r(m) = 0.174 of the control). In contrast, aphids fed with the DG18 line exhibited reduced adult survival and reproductive period but no alteration of their demographic parameters (r(m) = 0.176). Finally, no physiological alteration was induced in aphids fed on a DG20 diet (r(m) = 0.170). Behavioural experiments conducted in a 4-choice olfactometer demonstrated that insects were significantly more attracted by the odour of transgenic DG18 potato plant than that of Desiree non-transformed plant, spending twice as much time in the DG18 plant odour. The two other transformed clones ( DG5 and DG20) were as attractive as the non-transformed cultivar. It is concluded that the beta-glucuronidase expression in potato plants might be responsible for the probiotic effect measured on the feeding aphids, whereas alteration of the foliage odour would result from a pleiotropic effect.