Macfarlane Craig, Hansen Lee D, Florez-Sarasa Igor, Ribas-Carbo Miquel
CSIRO Forest Biosciences, Centre for Environment and Life Sciences, Private Bag No. 5, Wembley, Australia.
Plant Cell Environ. 2009 May;32(5):585-91. doi: 10.1111/j.1365-3040.2009.01953.x. Epub 2009 Feb 2.
We tested the hypotheses that relative activity of the less efficient alternative oxidase (AOX) path changes with diurnal temperature changes, and thus changes carbon use efficiency with temperature. The activities of the alternative and cytochrome oxidase (COX) paths in plant tissues of three species were determined by measuring 18O/16O discrimination and total respiration from 17 to 36 degrees C. A new, more accurate method for calculating oxygen uptake rate from the mass spectrometry data was developed. Total carbon use efficiency was calculated from the ratio of respiratory heat and CO2 rates measured from 10 to 35 degrees C. Oxygen isotope discrimination (22.9 +/- 0.4 per thousand) and AOX participation were invariant with temperature in leaf tissue of Cucurbita pepo, Nicotiana sativa and Vicia faba, thus falsifying the first part of the hypothesis. Stress responses of respiration at the temperature extremes limited the range for which carbon use efficiency could be accurately measured to 15-30 degrees C in N. sativa, to 10-25 degrees C in C. pepo and to 20-30 degrees C in V. faba. Carbon-use efficiency was invariant at these temperatures in these species, demonstrating that changes in other pathways that would vary carbon-use efficiency were also invariant with temperature.
效率较低的交替氧化酶（AOX）途径的相对活性会随昼夜温度变化而改变，进而随温度变化而改变碳利用效率。通过测量17至36摄氏度下的18O/16O分馏和总呼吸作用，测定了三个物种植物组织中交替途径和细胞色素氧化酶（COX）途径的活性。开发了一种新的、更准确的方法，用于根据质谱数据计算氧气摄取率。根据10至35摄氏度下测得的呼吸热与二氧化碳速率之比，计算总碳利用效率。在西葫芦、烟草和蚕豆的叶片组织中，氧同位素分馏（22.9±0.4‰）和AOX参与度不随温度变化，因此该假设的第一部分被证伪。在极端温度下呼吸作用的应激反应将可准确测量碳利用效率的温度范围限制为：烟草为15至30摄氏度，西葫芦为10至25摄氏度，蚕豆为20至30摄氏度。在这些温度下，这些物种的碳利用效率不变，表明其他会改变碳利用效率的途径的变化也不随温度变化。
