SRA

Background: The unprecedented rise in atmospheric CO2 concentration and injudicious fertilization or heterogeneous distribution of Mg in the soil warrant further research to understand the synergistic and holistic mechanisms involved in the plant growth regulation. The objective of this work is to understand responses in plants along with interactive effect of elevated CO2 and Mg levels by comparing data on single stress with that of combined stresses. Results: This study investigated the influence of elevated CO2 (800 µL L-1) on physiological and transcriptomic profiles in Arabidopsis cultured in hydroponic media treated with 1 µM (low), 1000 µM (normal) and 10000 µM (high) Mg2+. Following 7-d treatment, elevated CO2 increased the shoot growth and chlorophyll content under both low and normal Mg supply, whereas root growth was improved exclusively under normal Mg nutrition. Notably, the effect of elevated CO2 on mineral homeostasis in both shoots and roots was less than that of Mg supply. Irrespective of CO2 treatment, high Mg increased leaf number but decreased root growth and absorption of P, K, Ca, Fe and Mn whereas low Mg increased the concentration of P, K, Ca and Fe in leaves. Elevated CO2 decreased the expression of genes related to cadmium response, cell redox homeostasis and lipid localization, but enhanced photosynthesis, signal transduction, protein phosphorylation, NBS-LRR disease resistance proteins and subsequently programmed cell death in low-Mg shoots. By comparison, elevated CO2 enhanced the response of lipid localization (mainly LTP transfer protein/protease inhibitor), endomembrane system, heme binding and cell wall modification in high-Mg roots. Some of these transcriptomic results are substantially in accordance with our physiological and/or biochemical analysis. Conclusions: Contrasting changes were found between roots and shoots with the shoot transcriptome being more severely affected by low Mg while the root transcriptome more affected by high Mg. Elevated CO2 had a greater effect on transcript response in low Mg-fed shoots as well as in high Mg-fed roots. The present findings broaden our current understanding on the interactive effect of elevated CO2 and Mg levels in the Arabidopsis, which may help to design the novel metabolic engineering strategies to cope with Mg deficiency/excess in crops under elevated CO2. Overall design: Examination of two CO2 concentration and three Mg levels of shoot and root Arabidopsis