Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409.
Plant Physiol. 1992 Oct;100(2):979-86. doi: 10.1104/pp.100.2.979.
The effects of temperature on rates of cellulose synthesis, respiration, and long-term glucose uptake were investigated using cultured cotton ovules (Gossypium hirsutum L. cv Acala SJ1). Ovules were cultured either at constant 34 degrees C or under cycling temperatures (12 h at 34 degrees C/12 h at 15-40 degrees C). Rates of respiration and cellulose synthesis at various temperatures were determined on day 21 during the stage of secondary wall synthesis by feeding cultured ovules with [(14)C]glucose. Respiration increased between 18 and approximately 34 degrees C, then remained constant up to 40 degrees C. In contrast, the rate of cellulose synthesis increased above 18 degrees C, reached a plateau between about 28 and 37 degrees C, and then decreased at 40 degrees C. Therefore, the optimum temperature for rapid and metabolically efficient cellulose synthesis in Acala SJ1 is near 28 degrees C. In ovules cycled to 15 degrees C, respiration recovered to the control rate immediately upon rewarming to 34 degrees C, but the rate of cellulose synthesis did not fully recover for several hours. These data indicate that cellulose synthesis and respiration respond differently to cool temperatures. The long-term uptake of glucose, which is the carbon source in the culture medium, increased as the low temperature in the cycle increased between 15 and 28 degrees C. However, glucose uptake did not increase in cultures grown constantly at 34 degrees C compared to those cycled at 34/28 degrees C. These observations are consistent with previous observations on the responses of fiber elongation and weight gain to cycling temperatures in vitro and in the field.
使用培养的棉花胚珠（Gossypium hirsutum L. cv Acala SJ1）研究了温度对纤维素合成、呼吸和长期葡萄糖摄取速率的影响。胚珠在恒温和循环温度（34°C 下 12 小时/15-40°C 下 12 小时）下培养。在次生壁合成阶段的第 21 天，通过用 [(14)C]葡萄糖喂养培养的胚珠，在不同温度下测定呼吸和纤维素合成的速率。在 18 到约 34°C 之间，呼吸增加，然后在 40°C 时保持恒定。相比之下，纤维素合成的速率在 18°C 以上增加，在约 28 和 37°C 之间达到一个平台，然后在 40°C 时降低。因此，在 Acala SJ1 中快速且代谢高效的纤维素合成的最佳温度接近 28°C。在循环到 15°C 的胚珠中，呼吸在重新加热到 34°C 时立即恢复到对照速率，但纤维素合成的速率在几个小时内没有完全恢复。这些数据表明纤维素合成和呼吸对低温的反应不同。作为培养基中碳源的葡萄糖的长期摄取随着循环温度在 15 到 28°C 之间的增加而增加。然而，与在 34/28°C 下循环的培养物相比，在 34°C 下恒生长的培养物中葡萄糖摄取没有增加。这些观察结果与以前关于纤维伸长和重量增加对体外和田间循环温度的反应的观察结果一致。
