溫度對於水稻抽穗期間葉鞘中澱粉代謝的影響

Temperature Effects on Starch Metabolism in Rice Leaf Sheaths during Heading Period

蕭后廷(Hou-Ting Hsiao)

指導教授 ： 王淑珍

國立臺灣大學/生物資源暨農學院/農藝學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.01617

摘要

水稻在抽穗期前於葉鞘中累積的暫存性碳水化合物，於抽穗後會成為提供給穀粒充實的碳源之一。此外，葉鞘中的暫存性碳水化合物亦是於輕微的缺水逆境下使穀粒充實速度提高的碳供應源。水稻穀粒充實速度隨著溫度的提高而增加，為瞭解此時穀粒充實速度是否與葉鞘作為碳源供應有關，因此我們分析溫度對抽穗時期水稻葉鞘中澱粉代謝之影響。本論文將水稻分別於抽穗前與抽穗後兩個時期，並置於高溫(35/30℃)、低溫(15/13℃)與對照組(25/20℃)之溫室中，分別探討溫度對抽穗前葉鞘中澱粉累積之影響與抽穗後溫度對葉鞘提供碳水化合物能力的影響。在對照組(25/20℃)下，大多數的非結構性碳水化合物以澱粉的形式累積於葉鞘中。而低溫處理(15/13℃)下，葉鞘中的澱粉含量只有對照組的81.1%，但可溶性醣類含量則為對照組的171.8%。此外，高溫處理下(35/30℃)，葉鞘中的澱粉與可溶性醣類含量相較於對照組減少了許多，推測高溫下大量的同化物質被消耗。澱粉生合成酵素活性分析中SSS與GBSS在各溫度處理間的差異並不顯著，因此推測葉鞘中澱粉累積在高溫下較低，可能並非是因澱粉合成酶活性下降所造成。抽穗後高溫下葉鞘中的澱粉降解速度比25/20℃慢，而分析葉鞘中澱粉水解酵素α-amylase與β-amylase之活性，發現其酵素活性於高溫下沒有比對照組來得高，顯示葉鞘中澱粉降解速率並不會隨著溫度的提高，增加提供碳源至穀粒的速度。

關鍵字

水稻 ； 積儲-供源轉換 ； 高溫 ； 葉鞘 ； 澱粉

並列摘要

The temporal carbohydrate accumulated in leaf sheaths is an important carbon source during grain filling. Besides that, the temporal carbohydrate in leaf sheath also acculturate the grain filling rate when the rice subject moderate water stress. High temperature also acculturate the grain filling rate. In order to understanding the correlation between the grain filling rate and the carbohydrate supplying rate from leaf sheath . We analysis the temperature effects on starch metabolism in leaf sheath during heading period. My research was focused on the temperature effect on starch accumulation in leaf sheaths before heading and starch degradation in leaf sheaths at post-heading stage. The temperature that we treated on rice plants were 35/30℃, 25/20℃, and 15/13℃, respectively. Under the control condition, starch was rapidly accumulated in leaf sheaths during pre-heading period. Under lower temperature (15/13℃),the starch content in leaf sheaths was only 81.1% that in 25/20℃-treated rice plants (control plants), however the soluble sugar content was 171.8% that in control plants. On the other hand, high temperature treatment reduced both starch and soluble sugars content in leaf sheaths compared with control plants. We suggest that the plant lost a lot of assimilates under high temperature during treatment period. Since the GBSS and SSS activities were similar in leaf sheaths under different temperature treatment, the reduce of starch contents in high temperature-treated plants was not caused by starch synthase activities repressing. During post-heading period, the starch degradation rate is slower than that in 25/20℃, and the result showed that the amylase activities also didn’t higher than in 25/20℃. Therefore, the starch degradation rate in leaf sheath will not be accelerated by high temperature, and accelerate the carbon source supply to grain filling.

並列關鍵字

rice ； sink-source transition ； high temperature ； leaf sheath ； starch

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