Based on international findings, Irish co-existence guidelines for the
cultivation of GM potato stipulate that an isolation distance of 20 m is
required to minimize the spread of transgenic pollen in accordance with
required labeling thresholds. As potato tolerant to Phytophthora infestans is the most applicable GM
crop from an Irish context, we tested the efficacy of this isolation
distance under Irish environmental conditions using the conventional variety
Désirée as a pollen donor and the male-sterile variety British Queen
as a pollen receptor. Gene flow was determined by scoring for berry presence
on receptor plants and confirmed using a microsatellite marker system
designed to assess paternity in F1 seedlings. 99.1% of seedlings
recovered were identified as having Désirée paternity. Whereas
19.9% (140/708) of total berries formed on receptor plants occurred at a
distance of 21 m from the pollen source, only 4 of these berries bore viable
true potato seed (TPS), from which 23 TPS germinated. TPS-bearing berry
formation was negatively correlated with distance from the pollen source,
and although overall distribution of berries and seeds was non-random across
the plot, no significant correlation was evident with respect to wind
direction. Microsatellite markers were also used to confirm that the
foraging beetle Meligethes aeneus is a vector for the transmission of potato pollen, but a
more detailed statistical analysis of this dataset was limited by inclement
weather during the trial. To conclude, we recommend that a two-tiered system
be established in regard to establishing isolation distances for the
experimental trial and commercial cultivation of GM potato in Ireland, and
that responsible crop management be adopted to minimize the establishment of
TPS-derived volunteers, which we have noted will emerge through a rotation
as a result of pollen-mediated gene flow.