Study The Effects Of CO₂ On Stomatal Movement And Rare Earth On Root Growth In Plants

Stomatal pores were formed by adjustble guard cells in the plant epidermis of aerial tissues. They act as "gates", which controlled the exchangement of CO2 in plants with the atmosphere. O2,CO2 and H2O can pass through the gate freely. Plants need to control CO2 uptake and the water loss. By regulating the opening and closing of stomatal pores, the rate of CO2 influx to photosynthesis and the water loss of transpiration are controlled. The paper mainly studies the effects of the elevated CO2 on the stomatal movement in Arabidopsis thaliana. It has been shown that low concentration of CO2 would promote the opening of the stomatal, while the elevated concentration of CO2 would lead to stomatal closure. However, the regulation mechanisms of the stomatal movement were not further investigated. People paid more attention on the study of the ABA signaling pathway over recent years, and it has been known that the ABA signaling pathway and the CO2 signaling network have a cross talk. Some proteins mutants which were necessary protein in ABA induced-stomatal closure signaling pathway were used to inspect whether they are necessary proteins in CO2 induced-stomatal closure signaling pathway.We analysed the effects of elevated CO2 on induced-stomatal closure of ABA receptors protein(PYRl/PYL2/PYL2/PYL4)mutant pyrlpyllpy!2pyl4, ABI1(ABA INSENSITIVE) protein mutant abil-1,abi2-1,OST1 (OPEN STOMATA 1) kinase mutant ost1-3 and the variety of active oxygen content in the guard cells in Arabidopsis thaliana after CO2 dealing with them. In the present study, we show that ABA receptors protein(PYRl/PYL2/PYL2/PYL4), ABI1(ABA INSENSITIVE) protein kinase and OST1 (OPEN STOMATA 1) kinase may participate in the CO2 induced-stomatal closure signaling pathway. CO2 elevated ROS levels in CO2 induced-stomatal closure pathway, which is consistent with findings that ROS generation via NADPH oxidases which is encoded by the RbohD and F genes is involved in the pathway by which CO2 dominates stomatal development. In addition, we investigated stomata of the cal;ca4 double mutant are not impaired in responses to ABA, which suggests that β-carbonic anhydrases were not involved in ABA induced-stomatal closure pathway.China is not only the biggest county in rare earth reserve, but also a big consumer of rare earth as micro-fertilizer in agriculture, which accounts for the major part of the rare earth consumption. But the mechanisms of the rare earth effect on the plants needed to further investigated. In this paper, we also investigated the effects of rare earth elements La and Eu on the seed germination, root elongation growth and root hair development in Arabidopsis thaliana, and the effect of La on ABA elevated ROS levels in the root cell protoplasts. In the present study, we knew that at low concentrations, REE La and Eu would promote on the seed germination, on root elongation growth. Meanwhile, REE La attenuated the inhibition of ABA on seed germination, on root elongation growth. Interestingly, ABA can promote root hair growth, but REE La can’t promote root hair development. La inhibits ROS generation which was induced by ABA in root cell protoplasts in Arabidopsis thaliana.