Tuning of self-renewing capacity in theArabidopsisstomatal lineage by hormonal and nutrition regulation of asymmetric cell divisions

ABSTRACT Asymmetric and self-renewing divisions build and pattern tissues. In the Arabidopsis thaliana stomatal lineage, asymmetric cell divisions, guided by polarly localized cortical proteins, generate the majority of cells on the leaf surface. These divisions can be fine-tuned by systemic and environmental signals to modify tissue development, but the molecular mechanisms by which plants incorporate such cues to regulate asymmetric divisions are largely unknown. In a screen for modulators of cell polarity and asymmetric divisions, we identified a mutation in CONSTITIUTIVE TRIPLE RESPONSE 1 , a negative regulator of ethylene signaling. We subsequently revealed antagonistic impacts of ethylene and glucose signaling on the self-renewing capacity of stomatal lineage stem cells. Quantitative analysis of the impacts of these signaling systems on cell polarity and fate dynamics showed that developmental information may be encoded in both the spatial and temporal asymmetries of polarity proteins. Taken together, our results provide a framework for a mechanistic understanding of how systemic information such as nutritional status and environmental factors tune stem cell behavior in the stomatal lineage, ultimately enabling optimization of leaf size and cell-type composition.