Climate change has led to an increase in the frequency and severity of dehydration stresses such as low atmospheric humidity for plants. Humidity can vary significantly throughout the day and low humidity causes increased plant transpiration rate, whereby water is lost at a faster rate through stomatal pores on leaves. In response to low humidity, angiosperms can rapidly synthesise the stress hormone abscisic acid (ABA), triggering stomatal closure and preventing excessive water loss1. Previous studies have indicated that within the ABA biosynthesis pathway, only the genes encoding the rate-limiting enzyme nine-cis-epoxycarotenoid dioxygenase (NCED) are significantly induced within the timeframe of stomatal closure2–4. Despite their critical role, the genetic pathway responsible for the rapid upregulation of NCED genes and ABA biosynthesis remains uncharacterised.
To characterise the genes involved in this pathway, we are using the model plant Arabidopsis thaliana to investigate physiological and molecular responses at key time points during exposure to low humidity. We rapidly change the humidity of wild-type as well as candidate mutant plants to identify potential gene candidates for this pathway, by investigating the timing of physiological responses such as changes to plant water potential and gene expression, including induction of key NCED genes. This research aims to provide insights into the molecular mechanisms of plant stress responses, advancing our understanding of how plants survive in challenging and variable arid environments. These insights can inform future breeding efforts for enhancing stress tolerance.