Plant to plant gene flow is a route of environmental exposure for GM plants specifically
since crosses with wild relatives could lead to the formation of more vigorous hybrids,
which could increase the rate of introgression and the environmental impact. Here, we test
the first step in the process of potential transgene introgression: whether hybrid vigor
can be inherited to the next generation, which could lead to fixation of altered,
i.e., elevated, quantitative traits.
The potential for a permanent elevated fitness was tested using individual autogamous
progeny lineages of hybrids between the crop Lactuca sativa (Lettuce) and
the wild species Lactuca serriola (Prickly Lettuce). We compared progeny
from motherplants grown under either greenhouse or field conditions. The survival of young
plants depended strongly on maternal environment. Furthermore, we observed that offspring
reproductive fitness components were correlated with maternal fitness.
Our study demonstrates that post-zygotic genotypic sorting at the young plants stage
reduces the number of genotypes non-randomly, leading to inheritance of high levels of
reproductive traits in the surviving hybrid lineages, compared to the pure wild
relatives.
Consequently, directional selection could lead to displacement of the pure wild relative
and fixation of more vigorous genome segments originating from crops, stabilizing plant
traits at elevated levels. Such information can be used to indentify segments which are
less likely to introgress into wild relative populations as a target for transgene
insertion.