UC San Diego

Plants have evolutionarily developed mechanisms that enable them to adapt and respond to environmental stimuli, increasing plant survivability. A key component involved in these mechanisms are stomatal pores that regulate gas exchange. Stomatal pores are in charge of regulating the intake of CO2, which is used during photosynthesis to create energy, while releasing oxygen that humans and animals breathe and minimizing the amount of water loss via evapotranspiration. Plant water loss reduces leaf temperature and can be used as a tool to measure plant transpiration. In monocot grasses, stomatal pores are made up of two dumbbell-shaped guard cells and flanked by two subsidiary cells. These specialized subsidiary cells have been shown to play an important role in promoting faster stomatal opening and closing to stimuli like CO2. So far, very little is known about the different molecular elements involved in the CO2 sensing and response mechanisms in grasses. Therefore, to identify potential novel components involved in CO2-dependent stomatal movement, infrared thermal imaging was utilized in a forward genetic screen using EMS mutagenized plant lines from the grass model Brachypodium distachyon

Stomatal pores are found on the abaxial(lower) and adaxial(upper) side of leaves. Changes to the patterning or development of stomatal pores on leaves affects the overall gas exchange. The elements involved in stomatal development and patterning are well understood in the dicot, Arabidopsis thaliana. It has been shown that pro-peptide signals known as EPIDERMAL PATTERNING FACTORs (EPFs) regulate stomatal development. Moreover, it has been shown that some subtilase proteases from the (SBT) family can cleave EPF peptides. Cleaved EPFs in turn become activated EPF peptide signals, inducing stomatal regulation. The function of SBT proteases in the monocot, Brachypodium distachyon has not been investigated. Therefore, a reverse genetic screen was conducted as a pilot study using artificial microRNA technology to investigate if downregulating selected family members of the SBT family would affect stomatal development in the grass model