Adaptability of Indocalamus decorus to climate change based on physiological and biochemical responses to elevated carbon dioxide and ozone

Abstract

(1) Carbon dioxide (CO2) and ozone (O3) are important greenhouse gases that contribute to global climate change. The effects of elevated CO2 and/or O3 on plants remain unclear. Plant responses to mixtures of the two gases at high concentrations are likely to be complex. Previous studies have shown that the ability to tolerate elevated levels of the two gases varies among plant species; physiological adaptability in the face of changing atmospheric composition also differs among taxa. However, the effects of mixtures of the two greenhouse gases on the growth and physiology of bamboo are largely unexplored, even though bamboos are important vegetation elements throughout tropical and subtropical regions of the planet. In this study, we used open-topped chambers (OTC) to double the concentrations of atmospheric CO2 and O3, and examined changes in membrane lipid peroxidation, photosynthetic physiology, and antioxidase activities in Indocalamus decorus leaves. After 103 days of treatment, elevated O3 depressed net photosynthetic rate (Pn) without changing stomatal function, but caused no significant oxidative damage in the leaves. High levels of antioxidase activities were maintained in the leaves, indicating that this species had a strong tolerance to elevated O3. Decreases in reactive oxygen content and antioxidase activity in the leaves highlighted the significant positive effects of elevated CO2 on photosynthesis in I. decorus. When a mixture of both gases was supplied at high concentrations, we detected no oxidative damage, although photosynthetic capacity was reduced. Negative effects of O3 were very marked during the early part of the treatment period, but the effects of CO2 were positive. CO2 mitigated the oxidative damage caused by O3 and promoted the growth of I. decorus. Thus, I. decorus tolerated the two greenhouse gases, and was able to adapt to elevated CO2 and O3 levels. These findings contribute to the current knowledge base on the response of bamboo to global climate change.Keywords: Antioxidant Enzyme, Carbon Dioxide, Indocalamus decorus, Membrane Lipid Peroxidation, Ozone, Photosynthetic Physiology IntroductionThe impacts of global climate change on terrestrial ecosystems are intrinsically complex. In spite of the complexity, they are issues of broad public concern. Carbon dioxide (CO2) and ozone (O3) are important greenhouse gases that drive global climate change. A wide range of human activities, such as the rapid development of industry and transportation, heavy use of nitrogen fertilizers in agriculture, significant emissions of nitrogen oxides (NOx) and oxygen-containing volatile organic compounds (VOCs), have increased atmospheric CO2 and O3 concentrations to levels that are significantly higher than those prior to the industrial revolution. The rate of increase has been relatively stable over time. By 2050, the atmospheric CO2 concentration is expected to reach concentrations that will be double those of preindustrial levels; O3 is increasing by up to 2.5% annually (IPCC 2007). Significant i...

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“…Absorbance readings at 240 nm were recorded at 30‐s intervals over a duration of 3 min. Catalase activity was quantified based on a decrease in optical density (OD) of 0.01 min −1 , which was defined as one unit of activity (Guo et al 2015).…”