With our rapidly changing climate, plant communities are predicted to experience more variable conditions. Climate change predicts that there will be longer periods of drought followed by heavy rainfall at unpredictable intervals. With this, plants may experience selective pressures to combat the stress that come with these variable conditions, which ultimately may influence plant evolution.
Phenotypic plasticity and epigenetic modification are two factors we believe may strongly influence the adaptative ability of plants. These two factors combined could promote coping mechanisms for plants in stressful conditions. We have implemented an experimental design mimicking the predicted variable conditions of climate change. We used five genotypes of Arabidopsis thaliana that exhibit differing drought-adaptive strategies. For two generations, we exposed plants to either drought or non-drought conditions. Then in the third generation, we took seeds from parents that experienced drought or non-drought conditions and exposed them to either drought, non-drought, or variable watering in a cross-replicated design. This allows us to determine whether transgenerational plasticity and/or epigenetic modification would allow offspring in future generations cope with a variable or drought conditions. During each generation, quantitative phenotypic data such as fitness, biomass, height, and chlorophyll content was collected for each plant.
Results/Conclusions
In Generation 1 and 2, we found that fitness and chlorophyll content in all genotypes were generally higher in non-drought treatments, however, there were no significant differences between other trait for each treatment genotype combination. For generation 3, if the parent plant was exposed to either drought or non-drought conditions and the offspring plant was exposed to drought again, chlorophyll content on average was higher in plants whose parents were exposed to drought. Offspring plants that experienced drought had higher fitness than those who experienced non-drought conditions. This may suggest that prior experience of the parent plant may benefit offspring plants if exposed to similar conditions. If a plant is adapted to drought, it may be advantageous in adapting to variable conditions compared to if the parent plant was adapted to moist conditions. We also found that regardless of what treatment the parent received, for all genotypes, offspring plants that experienced variable conditions had higher biomass and fitness than those who experienced drought or non-drought conditions. Together, these results suggest the transgenerational plasticity plays a role in plant adaptation to a variable environment.