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標題: | 阿拉伯芥中bHLH51轉錄因子與FIN219間交互作用對於吉貝素和茉莉酸介導的信息調控之研究 Studies of transcription factor bHLH51 and FIN219 interaction in regulating the cross-talk between gibberellin- and jasmonate-mediated signaling in Arabidopsis |
作者: | 黃子瀚 Tzu-Han Huang |
指導教授: | 謝旭亮 Hsu-Liang Hsieh |
關鍵字: | bHLH51,GA2ox2,FIN219,茉莉酸,吉貝素, bHLH51,GA2ox2,FIN219,Jasmonates,Gibberellin, |
出版年 : | 2023 |
學位: | 碩士 |
摘要: | 植物荷爾蒙中茉莉酸 (jasmonates; JAs) 和吉貝素 (gibberellin; GA) 在植物防禦與生長的過程扮演重要角色,兩者相互拮抗,以調控它們之間的交互作用。吉貝素所引發的生長反應受到DELLA的抑制,而吉貝素的存在則能造成DELLA的降解,進而促進植物生長;這樣的調控機制則會受到茉莉酸的影響,造成DELLA的累積而抑制生長。本論文的研究顯示bHLH家族的轉錄因子bHLH51參與茉莉酸所介導的生長抑制之中。bHLH51的表達量會受到甲基茉莉酸 (methyl jasmonate; MeJA) 顯著性的誘導表現,並作用於茉莉酸生合成基因- FAR-RED INSENSITIVE 219 (FIN219) 的下游。當大量表達bHLH51,會導致植株矮小。矮小的外表型可能是RGA蛋白質的含量增加所造成,RGA屬於阿拉伯芥DELLA蛋白質的一員。根據實驗結果推測與吉貝素代謝基因的表現量變化相關。其中,bHLH51能直接結合到GA2ox2基因的啟動子區域,促進它的表現。GA2ox2能將具生物活性的吉貝素轉化為不具活性的型態。不僅如此,ChIP-seq和RNA-seq的結果也顯示出bHLH51主要作為轉錄活化子 (transcriptional activator)。此外透過偵測甲基茉莉酸處理下的表現量變化,顯示出bHLH51可能透過調控JAZ1的表達,以影響茉莉酸信息途徑的負回饋機制。有趣的是,bHLH51還造成FIN219的表現量下調,進而造成JA反應的抑制,形成了一個 bHLH51和FIN219間的回饋機制。除此之外,我們也發現bHLH51和FIN219之間存在著直接的交互作用,並推測FIN219可能藉此抑制bHLH51的功能。我們的研究顯示大量表達bHLH51時會引發水楊酸 (salicylic acid; SA) 相關反應,揭示轉錄因子bHLH51參與在水楊酸介導的植物免疫反應中的可能性。綜合以上所述,本研究提出bHLH51在阿拉伯芥中會響應外界的生物或非生物性逆境,進而抑制吉貝素的活性。 Jasmonates (JAs) play a critical role in plant defense and development. This phytohormone is antagonistic to the growth-promoting hormone gibberellins (GAs) and inhibits plant growth. JA reduces GA-mediated degradation of DELLA proteins, which are negative regulators of plant growth responses. In this study, we investigated the involvement of basic helix-loop-helix transcription factor 51 (bHLH51) in JA-mediated growth inhibition. We demonstrated that bHLH51 functions in downstream of FAR-RED INSENSITIVE 219 (FIN219), a biosynthetic enzyme of JA-isoleucine (JA-Ile). Exogenous methyl jasmonate (MeJA) treatment can substantially induce bHLH51 expression. Overexpression of bHLH51 causes a dwarf phenotype likely through RGA (one of the DELLA proteins), which correlates with changes in the expression of GA-metabolic genes. We provided evidence that bHLH51 directly up-regulated expression of the GA2ox2 gene, encoding an enzyme that catalyzes the conversion of an active GA into an inactive GA. Further ChIP-seq and RNA-seq analyses also indicated that bHLH51 acted as a transcriptional activator. Moreover, based on the expression level changes under MeJA treatments, we propose that bHLH51 is involved in the regulation of a JA signaling negative feedback through regulating JAZ1. Interestingly, bHLH51 also downregulated FIN219, thereby contributing to a suppression of JA responses, forming a bHLH51-FIN219 feedback loop. Besides, we found a physical interaction between FIN219 and bHLH51, which suggests the inhibition of bHLH51 function by FIN219. Our findings also revealed that salicylic acid (SA) responses were activated in bHLH51 overexpression lines, which suggests the potential role of bHLH51 in SA-mediated plant immunity. In summary, our study demonstrates that bHLH51 may respond to biotic or abiotic stresses while suppressing GA activity in Arabidopsis. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/88636 |
DOI: | 10.6342/NTU202302761 |
全文授權: | 同意授權(全球公開) |
顯示於系所單位: | 植物科學研究所 |
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