Changes in the activities of starch metabolism enzymes in rice grains in response to elevated CO2 concentration

• Published in: International journal of biometeorology 2016-05, Vol.60 (5), p.727-736
• Main Authors: Xie, Li-Yong, Lin, Er-Da, Zhao, Hong-Liang, Feng, Yong-Xiang
• Format: Article
• Language: English
• Subjects: 1,4-alpha-Glucan Branching Enzyme - metabolism; Amylose - metabolism; Animal Physiology; Biological and Medical Physics; Biometeorology; Biophysics; Carbohydrates; Carbon dioxide; Carbon Dioxide - pharmacology; Developmental stages; Earth and Environmental Science; Environment; Environmental Health; Enzymatic activity; Enzymes; Flowers; Glucose-1-Phosphate Adenylyltransferase - metabolism; Meteorology; Original Paper; Oryza - drug effects; Oryza - enzymology; Oryza - metabolism; Plant Physiology; Plant Proteins - metabolism; Rice; Starch; Starch - metabolism; Starch Synthase - metabolism
• ISSN: 0020-7128; 1432-1254
• DOI: 10.1007/s00484-015-1068-9

The global atmospheric CO 2 concentration is currently (2012) 393.1 μmol mol −1 , an increase of approximately 42 % over pre-industrial levels. In order to understand the responses of metabolic enzymes to elevated CO 2 concentrations, an experiment was conducted using the Free Air CO 2 Enrichment (FACE )system. Two conventional japonica rice varieties ( Oryza sativa L. ssp. japonica ) grown in North China, Songjing 9 and Daohuaxiang 2, were used in this study. The activities of ADPG pyrophosphorylase, soluble and granule-bound starch synthases, and soluble and granule-bound starch branching enzymes were measured in rice grains, and the effects of elevated CO 2 on the amylose and protein contents of the grains were analyzed. The results showed that elevated CO 2 levels significantly increased the activity of ADPG pyrophosphorylase at day 8, 24, and 40 after flower, with maximum increases of 56.67 % for Songjing 9 and 21.31 % for Daohuaxiang 2. Similarly, the activities of starch synthesis enzymes increased significantly from the day 24 after flower to the day 40 after flower, with maximum increases of 36.81 % for Songjing 9 and 66.67 % for Daohuaxiang 2 in soluble starch synthase (SSS), and 25.00 % for Songjing 9 and 36.44 % for Daohuaxiang 2 in granule-bound starch synthase (GBSS), respectively. The elevated CO 2 concentration significantly increased the activity of soluble starch branching enzyme (SSBE) at day 16, 32, and 40 after flower, and also significantly increased the activity of granule-bound starch branching enzyme (GBSBE) at day 8, 32, and 40 after flower. The elevated CO 2 concentration increased the peak values of enzyme activity, and the timing of the activity peaks for SSS and GBSBE were earlier in Songjing 9 than in Daohuaxiang 2. There were obvious differences in developmental stages between the two varieties of rice, which indicated that the elevated CO 2 concentration increased enzyme activity expression and starch synthesis, affecting the final contents of starch and protein in the rice grains. Our results will provide a foundation for understanding the physiological mechanisms of rice yield under elevated atmospheric CO 2 concentrations.