title: Increasing CO2 differentially affects essential and non-essential amino acid concentration of rice grains grown in cadmium-contaminated soils.
abstract: Environmental pollution by both ambient CO2 and heavy metals has been steadily increasing, but we do not know how fluctuating CO2 concentrations influence plant nutrients under high Cd pollution, especially in crops. Here, we studied the effects of elevated CO2 and Cd accumulation on proteins and amino acids in rice under Cd stress. In this pot experiment, we analyzed the amino-acid profile of 20 rice cultivars that accumulate Cd differently; the plants were grown in Cd-containing soils under ambient conditions and elevated CO2 levels. We found that although Cd concentrations appeared to be higher in most cultivars under elevated CO2 than under ambient CO2, the effect was significant only in seven cultivars. Combined exposure to Cd and elevated CO2 strongly decreased rice protein and amino acid profiles, including essential and non-essential amino acids. Under elevated CO2, the ratios of specific amino acids were either higher or lower than the optimal ratios provided by FAO/WHO, suggesting that CO2 may flatten the overall amino-acid profile, leading to an excess in some amino acids and deficiencies in others when the rice is consumed. Thus, Cd-tainted rice limits the concentration of essential amino acids in rice-based diets, and the combination with elevated CO2 further exacerbates the problem.
authors.affiliation: Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Environment, Ministry of Agriculture of China, Beijing 100081, PR China; Centre for Research in Ecotoxicology and Environmental Remediation, Agro-Environmental Protection Institute, Tianjin 300191, PR China. Electronic address: bekeyw@gmail.com.
authors.forename: Huibin
authors.initials: H
authors.lastname: Wu
authors.affiliation: Centre for Research in Ecotoxicology and Environmental Remediation, Agro-Environmental Protection Institute, Tianjin 300191, PR China. Electronic address: forestman1218@163.com.
authors.forename: Zhengguo
authors.initials: Z
authors.lastname: Song
authors.affiliation: Centre for Research in Ecotoxicology and Environmental Remediation, Agro-Environmental Protection Institute, Tianjin 300191, PR China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.affiliation: Centre for Research in Ecotoxicology and Environmental Remediation, Agro-Environmental Protection Institute, Tianjin 300191, PR China.
authors.forename: Zhongqi
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Centre for Research in Ecotoxicology and Environmental Remediation, Agro-Environmental Protection Institute, Tianjin 300191, PR China.
authors.forename: Shirong
authors.initials: S
authors.lastname: Tang
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D002104:Cadmium / Q000032:analysis / Q000633:toxicity*; D002245:Carbon Dioxide / Q000378:metabolism*; D018556:Crops, Agricultural / Q000378:metabolism; D004787:Environmental Pollution; D012275:Oryza / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis / Q000633:toxicity*
chemical_list: D000596:Amino Acids; D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D002245:Carbon Dioxide
keywords: Amino acids; CO(2) elevation; Cadmium; Food safety; Rice