Data_Stress-mediated variation in growth and adaptive ploidy plasticity in an invasive grass

Localized increase in cellular ploidy—endopolyploidy— is a common phenomenon during development and is also a primary response to stressful environments for many plant and animal species. Yet the evolvability of endopolyploidy as a plant stress response and its ecological consequences remain important open questions. Here we use 23 populations of a globally invasive grass collected from agricultural and non-agricultural habitat types to test for intraspecific variation in endopolyploidy levels, and how it corresponds with plant performance in response to three major stresses (herbicide exposure, simulated herbivory/mowing, and competition). Overall, plants significantly increased cell ploidy in response to herbicides and simulated herbivory/mowing, but not to competition. We found distinct phenotypic and endopolyploidy responses between plants from agricultural and non-agricultural habitats following herbicide application—suggesting that genotypic variation in ploidy plasticity may be adaptive, involved in compensatory growth responses, and influence plant-plant interactions. Populations with lower levels of endopolyploidy performed better in the field under intense competition with weeds, whereas populations with more endopolyploidy performed better under competition with corn. Together, our results shed light on an understudied adaptive response which plays an important role in how plants interact with each other, mitigate stress, and adapt to different environments.