Xie Li-Yong, Lin Er-Da, Zhao Hong-Liang, Feng Yong-Xiang
College of Agronomy, Shenyang Agricultural University, Shenyang, 110161, China.
Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
Int J Biometeorol. 2016 May;60(5):727-36. doi: 10.1007/s00484-015-1068-9. Epub 2015 Oct 4.
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.
目前（2012年）全球大气二氧化碳浓度为393.1 μmol mol⁻¹，比工业化前水平增加了约42%。为了解代谢酶对升高的二氧化碳浓度的响应，利用自由空气二氧化碳富集（FACE）系统进行了一项实验。本研究使用了在中国北方种植的两个常规粳稻品种（Oryza sativa L. ssp. japonica），松粳9号和稻花香2号。测定了水稻籽粒中ADPG焦磷酸化酶、可溶性和颗粒结合型淀粉合酶以及可溶性和颗粒结合型淀粉分支酶的活性，并分析了升高的二氧化碳对籽粒直链淀粉和蛋白质含量的影响。结果表明，升高的二氧化碳水平在开花后第8天、24天和40天显著提高了ADPG焦磷酸化酶的活性，松粳9号最大增幅为56.67%，稻花香2号为21.31%。同样，淀粉合成酶的活性从开花后第24天到开花后第40天显著增加，可溶性淀粉合酶（SSS）中松粳9号最大增幅为36.81%，稻花香2号为66.67%；颗粒结合型淀粉合酶（GBSS）中松粳9号为25.00%，稻花香2号为36.44%。升高的二氧化碳浓度在开花后第16天、32天和40天显著提高了可溶性淀粉分支酶（SSBE）的活性，在开花后第8天、32天和40天也显著提高了颗粒结合型淀粉分支酶（GBSBE）的活性。升高的二氧化碳浓度提高了酶活性峰值，松粳9号中SSS和GBSBE活性峰值出现的时间比稻花香2号早。两个水稻品种在发育阶段存在明显差异，这表明升高的二氧化碳浓度增加了酶活性表达和淀粉合成，影响了水稻籽粒中淀粉和蛋白质的最终含量。我们的结果将为理解大气二氧化碳浓度升高条件下水稻产量的生理机制提供基础。
