| 摘要: | RNA除了是遺傳資訊的傳訊者，也是細胞執行特定反應之催化者。依不同作用之需要，RNA可以為長鍊或短鍊所形成的構造。而為了確保RNA分子在不同狀態下進行該有之正確功能，有一群特定之蛋白質會維持或修改其結構。在這群蛋白質中，DEAD-Box RNA helicase 參與了細胞核中的轉錄、pre-mRNA的接合、rRNA的生合成、細胞核到細胞質的運輸、轉譯、RNA降解和基因的表現。文獻報告已指出，當細胞處於環境逆境時，改變RNA helicases的表現或活性，是細胞維持正常基因表現與逆境耐受力的重要關鍵因子之一。唯該方面的研究，主要集中在雙子葉植物。本研究計畫，則以水稻為主要研究對象，從探討RNA helicases在水稻中的分子功能與生理角色，進而培育出對環境逆境具有耐受性之水稻植株。研究策略主要分為兩大部分: (1) 從現有水稻與阿拉伯芥基因表現資料庫及過去的文獻中，我們已經篩選出可能與環境逆境相關的DEAD box RNA helicase基因，RH45 (At3g09620)、RH34 (At1g51380)、RH51 (At3g18600)與RH22 (At1g59990)，我們也已經建立了帶有RH22、 RH34、 RH45與RH51大量表現與基因靜默的轉殖阿拉伯芥。我們將進一步對這些轉殖株進行salt、drought或temperature stress反應的分析，釐清這些DEAD box RNA helicase基因是否在植物對抗環境逆境中扮演角色。我們也將建立相對應基因在水稻之大量表現及靜默表現轉殖株，再將這些轉植株置於逆境中，進一步釐清這些DEAD box RNA helicase基因在水稻中之正常生理功能與環境逆境耐受力所扮演的角色。此外，我們已發現大量表現OsRH36可增加阿拉伯芥對低溫逆境之耐受性，因此我們也將建構大量表現OsRH36之水稻轉殖株，以確定OsRH36對環境逆境耐受性之作用力。 (2) 從TRIM database 中取得DEAD box RNA helicase 之突變株，分析這些突變株對環境逆境的反應，進而撿選出與植物抵抗環境逆境相關的RNA helicase。結合以上兩個研究方針，預期將可找到抵抗不同環境逆境的DEAD box RNA helicases，經分子育種，產出耐逆境之水稻植株。未來更可以將此研究成果，推廣到其他的糧食作物上，以有效降低環境逆境所導致的作物損失，增加農業收益。 DEAD-box RNA helicases are enzymes that can rearrange RNA secondary structure and therefore control RNA metabolism and gene expression. As plants are sessile and require complex yet coordinated gene activity to survive in stress environments, it is plausible to suggest that the DEAD-box RNA helicases may play important roles for plants to cope with such adverse conditions. And recently, involvement of the DEAD-box RNA helicases in plant stress tolerance has been evidenced. For example, a cold stress-regulated DEAD-box RNA helicase, LOS4, was found to regulate a set of gene expression that is required for freezing tolerance. Meanwhile, Arabidopsis STRS1 and ATRS2, encoding DEAD-box RNA helicases, were also identified in a functional genomics screening and found to function as an upstream negative regulator of ABA-dependent and ABA-independent abiotic stress signalling networks. Despite of these facts that the DEAD-box RNA helicases can be crucial for plant stress tolerance, however, the studies in this topic to date used mainly Arabidopsis. Little is understood if crop plants employ similar mechanisms to withstand stressful environmental conditions, and whether manipulation of the activities of DEAD-box RNA helicases could generate stress-tolerant crop varieties. For that reason, this proposed research will study the roles of DEAD-box RNA helicases for stress resistance in rice (Oryza sativa). Two major strategies will be employed. Firstly, the publicly available rice mutant database (e.g., TRIM, Tos-17、Oryza Tag Line and POSTECH RISD) will be searched to identify and collect DEAD-box RNA helicases mutants. Their physiological, cellular and molecular responses to a variety of biotic stresses (e.g., salinity, drought and temperature) will be examined. RNAi experiments will also be conducted if the mutant lines of interest are unavailable. In addition, we have shown that ectopic expression of rice OsRH36 can confer cold stress tolerance in Arabidopsis. Therefore, we will analyze the ability of OsRH36-overexpressing rice to adapt environmental stresses. Secondly, taking advantage of the easy cultivation and well established molecular biology techniques of Arabidipsis, the identified rice DEAD-box RNA helicase genes will be transformed into Arabidipsis for quick analysis. And by combining the results from these works, we will have enough knowledge to develop better stress tolerant rice varieties through exploitable DEAD-box RNA helicases. 研究期間：9908 ~ 10007 |
