| ABA is a phytohormone that plays a major role in plant processes and homeostasis. ABA is a drought-induced phytohormone that regulates stomata. Stomata are pores in the aerial epidermal tissue of plants that are responsible for the exchange of gases, nutrient transport, and leaf cooling. In the ABA signaling pathway, PYR/PYL ABA receptor proteins and PP2Cs regulate the downstream response of stomatal closure in Ca2+-independent and Ca 2+-dependent pathway. Evidence shows that ABA elicits a downstream increase in [Ca2+]cyt and that [Ca2+]cyt is required for ~70% of the response. To study the potential relationship of PYR/PYL ABA receptor proteins and PP2Cs in calcium-dependent ABA signaling pathway, stomata were monitored after exposure to ABA and elevated Ca 2+ in Arabidopsis thaliana. PP2C mutant leaves showed hypersensitivity to ABA and Ca2+. PYR/PYL ABA receptor mutant showed no difference, in comparison to wildtype, when exposed to high Ca 2+; however there was a noticeable difference in [Ca2+] cyt elevations when leaf epidermis were exposed to ABA.;Malate is involved in stomatal regulation by changing [malate]cyt in guard cells in the presence of ABA. Building a FRET-based malate sensor would allow real-time monitoring of malate, in vivo. Malate sensor was designed by isolating the malate-binding domain of the YufLM two-component system from Bacillus subtillis. The sensor protein was purified and characterized based on the emission spectra, the binding affinity of the sensor to malate, and unspecific binding of other structurally similar substrates. Evidence shows that this malate sensor could potentially be used, in vivo, for future experiments. |
