灌浆结实期温度对早籼水稻籽粒淀粉合成代谢的影响

Effect of Temperature at Grain-filling Stage on Starch Biosynthetic Metabolism in Developing Rice Grains of Early-indica

利用人工气候箱 ,设高温 (日均温度 32℃ )和适温 (日均温度 2 2℃ ) 2个温度处理 ,研究了 2个早籼水稻品种在不同温度处理下籽粒灌浆过程中的蔗糖与淀粉含量、直链淀粉占总淀粉的比率及蔗糖合成酶 (SS)、ADPG焦磷酸化酶 (ADPG PPase)、可溶性淀粉合成酶 (SSS)、颗粒结合型淀粉合成酶 (GBSS)、淀粉分支酶 (SBE)、淀粉去分支酶 (DBE)的活性变化动态及其温度处理间的差异。研究结果表明 ,在籽粒灌浆初期 ,高温处理下籽粒中的蔗糖含量、淀粉含量及SS、ADPG PPase、SSS、SBE和DBE的活性均不同程度地高于适温处理 ,而在灌浆中后期 ,不同温度下籽粒中有关酶的活性变化与蔗糖含量、淀粉含量间的关系相对较为复杂 ;水稻籽粒灌浆过程中不同温度下籽粒中的SS、SSS活性差异与其淀粉积累过程的变化特征基本吻合 ,且对温度影响的反应较ADPG PPase敏感 ,可能是温度对籽粒中的淀粉合成代谢过程产生调控的重要位点 ;温度对水稻籽粒中直链淀粉占总淀粉比率的影响极为明显 ,高温处理使籽粒中直链淀粉占总淀粉比率降低 ,且不同温度处理间的差异在水稻灌浆的初期已开始显现 ,其原因可能与高温处理下相对较低的GBSS活性有关。 6种酶相比 。

Based on the experiment with two early indica rice varieties (Zhfu49 and Jiazao935) and two typical temperature treatments(the daily average temperature 32℃ and 22℃, respectively) in phytotrons, the sucrose content, starch content and ratio of amylose/ total starch and the activities of 6 key enzymes involved in starch synthetic metabolism of developing rice grains, including sucrose synthase (SS), soluble starch synthase (SSS), ADPG pyrophosphorylase (ADPG PPase), granule bound starch synthase (GBSS),starch branching enzyme(SBE) and debranching enzyme (DBE), and effect of temperature on their activities were analyzed. The results showed that, compared with proper temperature (22℃), higher sucrose content, higher starch content and higher activities of enzymes such as SS, ADPG PPase SSS, SBE and DBE could be generally found in grains at the beginning stage of grain filling in high temperature(32℃) treatment. However, at the middle and late stage of grain filling, there was a large difference existed in the change trend of such enzyme activities and their association with sucrose content and starch content was very complicated under the condition of different temperature treatments, but it could be seen that the activities of SS and SSS at 32℃ high temperature were always lower than that at 22℃ proper temperature, which was closely related to their variation in sucrose content and starch accumulating rate. The activities of SS and SSS were more sensitive to the temperature variation in comparison with ADPG PPase. It seems that SS and SSS were controlled by enzyme through which the temperature affected starch accumulating rate of rice grains. Difference of the amylose/total starch ratio in developing grains between 32℃ and 22℃ was significant and the lower amylsoe/total starch ratio was always showed in 32℃ high temperature treatment at the whole stage of grain filling process, which was closely related to the lower activity level of GBSS. Therefore, it could be concluded that effect of temperature on amylose/total starch was more attributable to GBSS rather than SS, SSS, ADPG PPase, SBE and DBE.