The role of transgenerational effects in adaptation of clonal offspring of white clover (<Emphasis Type="Italic">Trifolium repens</Emphasis>) to drought and herbivory

Environmentally induced transgenerational effects can increase success of offspring and thereby be adaptive if offspring experience conditions similar to the parental environment. The ecological and evolutionary significance of these effects in plants have been considered overwhelmingly in the context of sexual generations. We investigated whether drought stress and jasmonic acid, a key hormone involved in induction of plant defenses against herbivores, applied in the parental generation, trigger transgenerational effects in clonal offspring of Trifolium repens and whether these effects are adaptive. We found that drought stress experienced by parents significantly affected phenotypes of offspring ramets. Offspring ramets were bigger if they were produced in the parental water regime (control/drought). Repeated application of jasmonic acid to parents increased the subsequent growth of offspring ramets produced by stolons after they were disconnected from the parental clone. However, these offspring ramets experienced similar herbivory by the generalist Spodoptera littoralis caterpillar as did control offspring ramets, indicating that this jasmonic acid application in the parental generation did not result in a transgenerational effect comprising increased herbivory resistance. We conclude that, overall, environmental interaction in the parental generation can trigger transgenerational effects in clonal plants and some of these effects can be adaptive. Moreover, transgenerational effects in clonal plants that significantly influence their growth and behavior can ultimately affect the evolutionary trajectories of clonal populations.