TRANSGENIC POTATO PLANTS WITH ENHANCED RESISTANCE TO THE PEACH-POTATOAPHID MYZUS-PERSICAE

Potato plants (Solanum tuberosum) cv. Desiree were transformed with th e genes encoding the proteins bean chitinase (BCH), snowdrop lectin (G NA) and wheat a-amylase inhibitor (WAI) under the control of the const itutive CaMV 35S promoter. Transgenic plants with detectable levels of foreign RNA were then selected for further characterisation with resp ect to protein expression levels by immunodot blot analysis using poly clonal antibodies raised against the respective protein. With the exce ption of WAI, plants expressing high levels of RNA, expressed correspo ndingly high levels of the foreign protein (1.5-2.0% of the total solu ble protein). Although high levels of WAI mRNA were detected in some o f the transformants, the protein could not be detected. On the bases o f expression levels, two lines, designated PWG6#85 (transformed with t he double construct WAI/GNA) and PBG6#47 (transformed with the double construct BCH/GNA), were selected for testing in aphid trials for enha nced levels of resistance. Both transgenic lines had a marked and sign ificant effect on fecundity. The number of nymphs produced per female per day peaked at 4.1 and 4.2 for lines PBG6#47 and PWG6#85 respective ly, compared to a value of 5.4 on control plants. Total nymphal produc tion was also significantly lower on either of the transgenic lines co mpared to control plants (P<0.001) with the differences between the li nes being only just significant (P= 0.058). On line PBG6#47 there was a delay in nymphal production of 1.6 days, representing a delay of 15% , and on line PWG6#85 this was 3.2 days, representing a delay of ca. 3 0%. The intrinsic rates of increase (r(m)) were also significantly low er on both of the transgenic lines in comparison to that on control pl ants (P<0.001), however the differences between the lines were not sig nificant. The potential of using such genes as part of an over all str ategy for the control of aphid populations is discussed.