Global invader shows varied regrowth and adaptive ploidy plasticity to stress

Background/Question/Methods Localized changes in cellular ploidy (endoreduplication) are a common phenomenon in development and can be a genomic-level response to environmental variation in many plant and animal species. Whether this ploidy plasticity is an adaptive stress response and its consequences for ecological and evolutionary processes remain open questions. Here we use 47 accessions of an invasive grass, Sorghum halepense, collected from agricultural and non-agricultural habitats, to test for intraspecific variation in cellular ploidy, and its relationship to plant performance in response to stress. Stresses included herbicide application, simulated herbivory (clipping), and competition.

Results/Conclusions Overall, plants significantly increased their genomic content in response to all forms of stress with the exception of competition. Importantly, we find differences in responses of plants from agricultural and non-agricultural habitats—suggesting local adaptation of growth and cellular level processes. When compared with field performance data from a separate study, populations with the least plasticity in genomic content in this experiment demonstrated greater performance under intense competition with weeds in the field, while populations with higher plasticity performed better under competition with corn. Together, these results shed light on an understudied genomic response which has been posited to play an important role in how plants interact with each other, mitigate stress, and adapt to different environments.