Interactive Effects of Genes and Environment on Vegetative and Reproductive Tradeoffs of Leaf Size Mutants

Insights into phenotypic plasticity in leaf traits provide context for how plants maintain adequate resource acquisition across changing environments. Whether insertion mutations that influence early seedling rosettes translate into differences in reproductive success and phenotypic plasticity across nutrient and temperature environments is less known. We selected Arabidopsis thaliana mutant lines associated with a single insertion mutation in a common genetic background from a screen that categorized rosettes into two sets based on qualitative seedling size (increase or decrease) in comparison to wildtype and natural accessions. Our experiment under nutrient and temperature treatments showed the decrease set of mutant lines maintained smaller rosettes at bolting across environments, whereas the same was not found for the increase set, which revealed greater within-set variation. Nutrients increased fruit production, particularly at 20°C, whereas the warmer temperature (24°C) increased fruit abortion and tended to reduce fruit production, with stronger effects in the increase set. For the mutant lines studied for physiology, we found CO₂ assimilation patterns were broadly similar across temperatures despite rosette size differences, suggesting that this aspect of physiology does not explain rosette differences. Treatment responses were not parallel across sets of lines, indicating substantial among-line variation. The variation in phenotypic traits across abiotic environments in single gene-insertion mutants offers new quantitative insights into tradeoffs between rosette and reproduction. With data on genetic mechanisms behind plasticity, our results highlight how individual mutations can generate context dependent variation in vegetative and reproductive traits and trait relationships, useful for informing other plants' responses to climate change.