Transgenerational effects of stress on reproduction strategy in the mixed mating plant Lamium amplexicaule

Background: The theory of Condition Dependent Sex predicts that – everything else being equal – less fit individuals would outcross at higher rates compared with fitter ones. Here we used the mixed mating plant Lamium amplexicaule, capable of producing both self-pollinating closed flowers (CL), alongside open flowers (CH) that allow cross pollination to test it. We investigated the effects of abiotic stress – salt solution irrigation – on the flowering patterns of plants and their offspring. We monitored several flowering and vegetative parameters, including the number and distribution of flowers, CH fraction, and plant size. Results: We found that stressed plants show an increased tendency for self-pollination and a deficit in floral and vegetative development. However, when parentally primed, stressed plants show a milder response. Un-stressed offspring of stressed parents show reversed responses and exhibit an increased tendency to outcross, and improve floral and vegetative development. Conclusions: In summary, we found that stress affects the reproduction strategy in the plants that experienced the stress and in subsequent offspring through F2 generation. Our results provide experimental evidence supporting a transgenerational extension to the theories of fitness associate sex and dispersal, where an individual’s tendency for sex and dispersal may depend on the stress experienced by its parents.