Study The Mechanism Of CO₂-induced Stomatal Movement In Arabidopsis

Stomatal pores are formed by pairs of specialized epidermal guard cells and serve as major gateways for both CO2 influx into plants from the atmosphere and transpirational water loss of plants. Because they regulate stomatal pore apertures via integration of both endogenous hormonal stimuli and environmental signals, guard cells have been highly developed as a model system to dissect the dynamics and mechanisms of plant-cell signaling. The stress hormone ABA and elevated levels of CO2 activate complex signaling pathways in guard cells that are mediated by kinase/phosphatase, secondary messengers and ion channel regulation.Calcium-dependent protein kinases (CDPKs), which are widely involved in stomatal movement and response to various environmental stresses, are essential sensors of Ca2+ flux in plant. Hydrogen sulfide (H2S) has been proved to be the third gasotransmitter. In animals, it is involved in varieties of important physiological processes, such as insulin secretion, vasodilation, cell cycle, inflammation, stress response and so on. In plants, H2S has been identified involved in the regulation of physiological processes, including the regulation of stomatal movement.In this study, we focus on the role of CDPKs family members CPK3 CPK6 and H2S in response to CO2 stress in Arabidopsis.1. We explored whether CPK3 and CPK6 play a role in CO2 signal pathways by obtaining cpk3-1, cpk6-1, cpk3-1/cpk6-1 homozygous mutants. The results showed that, (1) In CO2 signal pathways, CPK3 and CPK6 may have no function. (2) Some genes encoding ion channel expressed significantly different at different concentrations of CO2 treatment, but the expression of these genes is little changed in cpk3-1, cpk6-1, cpk3-1/cpk6-1 mutants.We explored the relationship between the H2S signal and CO2 signal. (1) Through the acquisition of thermal image, and the analysis of stomatal index and the initial stomatal aperture and stomatal conductance. The stomatal conductance of led mutant showed significant differences compared with wild type after exposed to the elevated CO2, suggesting that H2S may be involved in the CO2 signaling pathway; (2) After elevated CO2 treatment, the content of reactive oxygen species increased both in mutation and wild type, moreover the difference was significant extremely. Further evidence showing of the cross-talk between H2S signal and CO2 signal provides a powerful clue for the further research of the physiological function of H2S in plants and the mechanism of CO2-mediated stomatal movement.