Molecular Mechanisms For Calcium Signaling Perceive Salt Stress In Arabidopsis Thaliana

Salinity is a major abiotic stress in plant affecting a many part of world. This has led to research into salt tolerance with the aim of improving crop plants. As we known, Ca2+-signaling pathways can regulate gene expression in plants. Upon environmental stimuli, calcium ions are released from intracellular storage compartments as well as from extracellular space, leading to an increase of cytosolic free Ca2+concentration ([Ca2+]i) by opening Ca2+channel. Plasma membrane Ca2+channels play a critical role in a variety of cellular processes by regulating [Ca2+]i. Increase in [Ca2+]i has been observed in many stress-activated signaling pathways. However, the mechanism of how plants sense these environmental stresses and thereby initiate the [Ca2+]i increase still remains unknown.Here, we use Arabidopsis thaliana constitutively expressing Ca2+sensitive photoprotein APOAEQUORIN to study the mechanisms of perceive pathway by different abiotic stress including salt stress and oxidative stress. Trying to find the salt senser and salt-induced Ca2+channel via screen T-DNA insertion mutants with defects in early calcium signalling in response to salt stress in Arabidopsis thaliana. The main results are showed as follows:(1) Analysis the result of NaCl-and H2O2-induced [Ca2+]i increased indicate plant cell unable keep [Ca2+]i sustained increase and unable maintain [Ca2+]i in a high level under stress.(2) NaCl-and H2O2-induced different Ca2+signaling pathways that indicate NaCl-and H2O2-evoked [Ca2+]i increase via different machineries.(3) One stimulus-induced [Ca2+]i increases inhibited likely this stimulus-gated channels more than the other stimulus-gated channels, suggesting a feedback mechanism, as well as the inhibitory interaction between two stimuli-mediated Ca2+signaling pathways.(4) Screen T-DNA insertion mutants with defects in early calcium signalling in response to salt stress in Arabidopsis thaliana. We got two mutants named sic1and sic2(defect in salt-induced calcium increase). Calcium fluorescence image show the [Ca2+]i fluorescence phenotype of sic1and sic2with an obvious attenuated under salt stress.(5) We evaluated the salt sensitivity of the sicl and sic2are more sensitive to NaCl stress than wild type under salt stress conditions.(6) Observe SIC2subcellular localization by gene expression pattern of sic2using the35S:sic2-GFP transgenic line, our results suggest that sic2functions as a regulator of Ca2+channel under salt stress or maybe regulate a salt senser during plant perceive salt stress.Based on these results, trying to clarify the molecular mechanism of calcium signal perceive salt stress in Arabidopsis thaliana. Laid the theoretical basis for further study the pathway that plant resistance to salt stress.