充實期遭遇高溫對水稻穎果內生育醇、生育三烯醇、γ-穀維素含量之影響及其與穀粒品質之關係

High temperature effects on tocopherol, tocotrienol, γ-oryzanol levels and their correlation with rice grain quality during grain filling stage.

吳昌烜(Chang-Hsuan Wu)

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(2013年)

https://doi.org/10.6342/NTU.2013.10053

摘要

近年國人生活水準與健康意識的提升，對飲食的品質亦逐漸重視，而稻米內富有機能性成分如生育醇 (Tocopherol)、生育三烯醇 (Tocotrienol) 與γ-穀維素 (γ-oryzanol) 等，可供醫藥、化妝品及健康食品之利用，因此提高水稻之生育醇、生育三烯醇與γ-穀維素可增加米食之附加價值與多樣性。文獻指出水稻中生育醇、生育三烯醇與γ-穀維素之含量會受到強光、低溫、乾旱等栽培逆境環境變化影響，但較少探討高溫逆境對這些機能性成分的影響，更少探討其與品質之間的關係。為明瞭高溫對不同品種水稻充實期穎果內機能性成分之影響，本試驗針對高溫對水稻穎果品質、生育醇、生育三烯醇及γ-穀維素之影響及其間之關連進行探討。試驗分為田間試驗與溫室試驗兩部分，田間試驗分為由臺中區農業改良場所提供高溫下充實之20種不同水稻品種分析生育醇、生育三烯醇及γ-穀維素含量，以瞭解田間環境中各品種間之差異性。此外，為了解田間稻穀充實期溫度對水稻穎果內之生育醇、生育三烯醇及γ-穀維素含量之影響，再以苗栗區農業改良場周年栽培種植之臺稉9號水稻進行分析。溫室試驗則選擇KS139、TK9及HL21三個品種之水稻種植於臺灣大學人工氣候室，於穎果充實期進行高溫處理 (35/30℃，日/夜溫) 12天，取各發育階段穎果進行穎果生理、粒重及外觀品質分析，並利用高效液相層析 (HPLC) 分析生育醇、生育三烯醇及γ-穀維素含量，進一步以即時定量聚合酶連鎖反應 (Real-time Quantitative PCR) 分析逆境反應、生育醇、生育三烯醇及γ-穀維素等相關基因表現。
田間試驗顯示，高溫逆境下水稻穎果之生育醇、生育三烯醇及γ-穀維素之含量與變化，會受到栽培環境變化影響且存在著品種間差異。試驗結果顯示，水稻穎果充實期遭遇高溫可促進穎果內醣解作用，推測可促進二次代謝生化路徑如Shikimate及MEP/DOXP pathway所需之前驅物的生成。分析發育穎果內之生育醇、生育三烯醇與γ-穀維素代謝之相關基因，顯示高溫會促進充實期第9-15天之穎果內TAT、HPPD、DOXPS、GGR及PNX等基因表現，暗示生育醇、生育三烯醇與γ-穀維素可能在此階段大量生成。此外結合高溫下之穎果生理代謝流與生育醇含量發現生育醇前驅物phytyl diphosphate (PDP) 之來源除MEP/DOXP pathway外，可能亦可由Chlorophyllase降解葉綠素而再生出PDP。穎果外觀品質方面，生育醇、生育三烯醇可能可影響高溫下穎果發育，減緩高溫對穎果外觀品質及粒重之影響，而γ-穀維素與稻米外觀品質間則無顯著的相關性。
本試驗提供了溫度、米質以及生育醇、生育三烯醇、γ-穀維素之間影響的基本關係架構，並初步瞭解了多品種水稻穎果在高溫下此二類機能性成分的變異性。但未來仍須進一步確認各品種之生育醇、生育三烯醇、γ-穀維素與米質之生理機制，以選育及栽培出優良品質及富含生育醇、生育三烯醇、γ-穀維素成分之品種。

關鍵字

高溫 ； 生育醇 ； 生育三烯醇 ； γ-穀維素 ； 稻米品質

並列摘要

In recent years, people pay more attention to food quality with the improvement of living standards and health consciousness. Rice grains contain abundant of tocochromanols (tocols) and γ-oryzanol, which could be used in pharmaceutical, cosmetics and food industry; however, their levels in rice grains could be affected by cultivation environmental changes. Little studies have been reported on the relationships among tocols, γ-oryzanol and grain quality in rice. In this study, we tried to demonstrate whether the levels of tocols and γ-oryzanol were response to poor grain quality with high temperature. In field experiment, 20 rice cultivars were analyzed by HPLC to determine the levels of tocols and γ- oryzanol of brown rice. In phytotron experiment, the levels of grain chalkiness, oxidative state, chlorophyll, tocols, γ-oryzanol and gene expression were analyzed in developing rice grain of three rice cultivars, KS139, TK9 and HL21.
The expression of cyPPDKB was increased by high temperature indicated that high level of pyruvate and phsophoenolpyruvate (PEP) may promote the biosynthesis of tocols and γ-oryzanol. Inducing expression of TAT, HPPD, DOXPS, GGR and PNX with high temperature at 9- to 15-day grain further supported that the biosynthesis of tocols and γ-oryzanol were elevated. The accelerated decrease of chlorophyll on dry weight base suggested that regeneration of phytyl diphosphate may provide an alternative resource to support biosynthesis of tocols. Moreover, poor grain quality was induced by high temperature could be ameliorated by high tocols content inside developing grain. In field experiment, the high levels of tocols in TY3, TK2 and KS139 showed that these three varities would be good candidates with good grain quality under high temperature condition.
This thesis revealed the prelimentary relationships among tocols, γ-oryzanol and rice grain quality under high temperature. Although the content of tocols among different cultivars was detected in this study, the mechanism to affect the differences of tocols content induced by high temperature still unclear. To further elucidate the interaction among grain quality, tocols and γ-oryzanol in different varities could provide a reference for developing rice varities with good grain quality and high tocols and γ-oryzanol.

並列關鍵字

high temperature ； tocopherol ； tocotrienol ； γ-oryzanol ； rice grain quality

參考文獻

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