Endopolyploidy is associated with leaf functional traits and climate variation in Arabidopsis thaliana

Premise: Endopolyploidy is widespread throughout the tree of life and is especially prevalent in herbaceous angiosperms. Its prevalence in this clade suggests that endopolyploidy may be adaptive, but its functional roles are poorly understood. To address this gap in knowledge, we explored whether endopolyploidy was associated with climatic factors and correlated with phenotypic traits related to growth.

Methods: We sampled stem and leaf endopolyploidy in 56 geographically separated accessions of Arabidopsis thaliana grown in a common garden to explore species variation and to determine whether this variation was correlated with climatic variables and other plant traits.

Results: Stem endopolyploidy was not associated with climate or other traits. However, leaf endopolyploidy was significantly higher in accessions from drier and colder environments. Moreover, leaf endopolyploidy was positively correlated with apparent chlorophyll content and leaf dry mass.

Conclusions: Endopolyploidy may have a functional role in the storage of chloroplasts and starch, and it may offer an adaptive avenue of tissue growth in cold and dry environments.

Keywords: PET ratio; annual mean temperature; chlorophyll concentration; days to bolting; endopolyploidy index; endoreduplication; flow cytometry; leaf size; natural variation; specific leaf area.