Photoperiod regulation of stomatal opening in Arabidopsis

Stomatal guard cells have a central role as regulators of gas exchange: CO2 entrance (used for photosynthesis) and loss of water as vapour. Stomatal aperture is extremely sensitive to environmental conditions such as temperature, water availability and the quality and quantity of light. Previous work suggested that photoperiod strongly affects stomatal opening. Moreover, our lab has shown there are differences in the pathways by which stomata are regulated in long days (“summer”) and in short days (“winter”). However, the mechanisms by which photoperiod controls stomatal opening are poorly understood.

The goal of our research is to characterize components of the photoperiod pathways that regulate stomatal aperture in Arabidopsis. In previous work we have identified stomatal-related genes that show differential expression in long and short days. Some of these genes are involved in signal transduction pathways of ABA and ultimately alter stomatal movements.

From the many genes that have been identified, ten key genes were chosen. We have obtained lines of Arabidopsis with mutations in these genes and are presently examining whether and how stomatal opening, water loss and growth are affected in long and short photoperiods. For example, in short days, mutations in PYL5 (PYRABACTIN-LIKE 5) cause increased water loss and reduced growth rate as compared to wild type plants.

A deeper understanding of how photoperiod affects stomatal movements could result in plants with optimized water use and possibly extend crop growth to areas that were once too dry to use for farming.