溫度逆境對不同穗位的乙烯合成及水稻穎果發育之影響

Effects of temperature stress on ethylene synthesis and rice caryopsis development during grain-filling stage

李雅婷(Ya-Ting Lee)

指導教授 ： 盧虎生

國立臺灣大學/生物資源暨農學院/農藝學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.01769

摘要

水稻穎果充實期遭遇溫度逆境易造成產量下降，提高白堊質發生率，降低外觀品質。本研究室前人研究指出充實期高、低溫會影響水稻穀粒澱粉合成和澱粉粒的堆疊，此外乙烯與心腹白的形成最具有相關性。為瞭解乙烯是否調控溫度逆境降低稻米品質的生理形成過程，本試驗以台灣良質米台梗九號為材料，在穎果充實期進行高溫(35 / 30 oC,日/夜溫)、常溫(25 / 20 oC,日/夜溫)以及低溫(20 / 15 oC,日/夜溫)三種溫度處理，取各處理的糙米進行品質外觀分析；取前50 ％開花的小穗為強勢穗位，剩下50 %為弱勢穗位，利用不同發育天數的穎果進行乙烯、H2O2、ATP、葉綠素含量和pH值等生理分析；最後使用即時定量聚合酶連鎖反應(Real-time Quantitative PCR)分析上述生理過程的相關基因表現情形。
品質分析結果顯示，高溫降低糙米粒重及儲存性澱粉和蛋白質的含量，此現象在弱勢穗位更明顯；低溫雖提高不孕小穗比例和降低粒重表現，但不影響外觀品質。乙烯釋放量分析顯示，高、低溫都會促使穎果的乙烯釋放量增加，但表現的時間點不同，弱勢穗位的乙烯釋放增加量更為明顯。由氧化逆境相關生理結果指出，高溫會促進H2O2累積，加速葉綠素降解及加遽細胞死亡的情況；ATP含量分析顯示高溫導致發育穎果內ATP濃度低下；pH值測定結果表示高、低溫都會促使胚乳細胞酸化。基因表現分析顯示，穎果內的澱粉和蛋白質合成酵素基因受高溫抑制表現，調控有氧呼吸的TCA cycle基因也於高溫下表現量降低，但酒精發酵的酒精脫氫酶(ADH)表現受到高溫促進，顯示穎果內能量使用與乾物質累積皆受高溫抑制；高溫導致穎果內CATB和DHAR的表現量下降，促使穎果內H2O2含量增加引發後續的氧化傷害；高溫誘導乙烯生合成基因表現時機提前，並引發下游轉錄因子的表現活性，低溫則是延後該群基因大量表現之時間；而多元胺和ABA合成代謝基因在高、低溫下的差異表現，影響了穎果遭受乙烯傷害的程度。另於高溫下於穎果進行外加AOA處理，可以明顯提高儲存性澱粉和蛋白質的含量、增加穀粒重並提高完整米率；在常溫下處理ACC則顯著降低成熟穎果的產量及外觀表現。研究結果顯示，乙烯確實參與水稻穎果對高、低溫度的生理反應，進而影響品質的形成。

關鍵字

乙烯 ； 溫度逆境 ； 水稻 ； 穎果

並列摘要

Temperature stress impacts grain quality and yield in grain-filling stage of rice. Ethylene manipulation during heading stage of rice correlates positively with chalkiness. In this study, rice cultivar TK9 was used as experimental material. After flowering, the flowering rice plants were moved to growth chamber for temperature treatments (20, 25 and 35 oC) for 15 days. In order to understand the regulatory mechanism between ethylene and temperature treatments, GC was utilized to analysis the ethylene evolution rate in the temperature treatment phase. Mature grain quality and storage content and physiologic responses of the developing grain were investigated. Real-time quantitative PCR was further utilized as a tool to realize the responses of the gene expression involved in related physiological processes.
In appearance of the grain quality analysis, high temperature defected grain quality. Poor grain quality, grain weight reducing and lower storage contents were occurred by high temperature. Superior spikelets had higher grain weight and better quality than inferior spikelets. The percentage of sterility spikelets was the highest at low temperature treatment. In physiologic analysis, including chlorophyll, H2O2, and ATP assays, high temperature increased H2O2 accumulation and chlorophyll degeneration and also decreased ATP concentration, but low temperature had opposite results. Both high and low temperatures caused acidification and cell death. In ethylene evolution rate analysis, both high and low temperatures accelerated ethylene evolution peak, and inferior spikelets had higher amount of ethylene evolution than superior spikelets. In gene expression analysis, high temperature restrained the gene expressions of starch synthesis enzymes, protein synthesis enzymes, anti-oxidation enzymes and PDHA3, and it as well increased the gene expressions of ADH and PAO. Compared with high temperature, low temperature delayed the time of the gene expressions of starch synthesis enzymes and protein synthesis enzymes. Genes involved in ethylene synthesis and ethylene transcription factors all induced at the early stage of developing caryopsis under high temperature. Treatment of high temperature (35 oC) with 1-aminocyclopropane-1-carboxylate (AOA) increased the content of starch and protein, grain weight and the percentage of perfect grains. Treatment of normal temperature (25 oC) with 1-aminocyclopropane-1-carboxylate (ACC) decreased yield and the appearance quality. These results revealed that temperature stress influence physiological pathways by ethylene, and the inhibition of ethylene synthesis can improve the appearance quality and grain yield at the early grain-filling stage.

並列關鍵字

ethylene ； temperature stress ； rice ； caryopsis

參考文獻

林芹如 (2008) 充實期高溫影響稻米品質形成的生理途徑. 國立台灣大學農藝學系 碩士論文

林韶凱 (2005) 高溫與水稻穎果基因表現及稻米品質形成相關性之研究. 國立台灣大學農藝學系 博士論文

許書華 (2012) 高溫下水稻充實期多元胺與水稻品質形成的關係. 國立台灣大學農藝學系 碩士論文

陳瀅如 (2009) 乙烯和多元胺對高溫下水稻穀粒發育的關係. 國立台灣大學農藝學系 碩士論文

楊凡萱 (2010) 氮素對高溫下水稻穀粒品質形成之緩解作用之研究. 國立台灣大學農藝學系 碩士論文