- 學位論文
水稻細胞分裂素訊息擬磷酸轉運蛋白 OsPHP3 之生理功能探討
Physiological Studies on Pseudo-Histidine Phosphotransfer Protein 3 (OsPHP3) in Rice
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摘要
細胞分裂素為調控植物生長分化與非生物逆境耐受性的重要植物荷爾蒙，而細胞分裂素訊息主要是經由多步驟的雙分子訊息傳導系統進行傳遞。磷酸轉運蛋白 (histidine phosphotransfer protein，HP) 具有保守性組胺酸片段，能接收膜上組胺酸激酶 (histidine kinase，HK) 的磷酸訊息，並轉運至細胞核內的反應調節子 (response regulator，RR)，啟動下游細胞分裂素的初期反應。前人研究顯示阿拉伯芥細胞分裂素訊息磷酸轉運蛋白6 (Arabidopsis histidine phosphotransfer protein 6，AHP6) 與 HP 的胺基酸序列具有高相似性卻缺乏保守性組胺酸片段，為細胞分裂素訊息傳導系統中的負向調控因子。水稻細胞分裂素訊息擬磷酸轉運蛋白 (Oryza sativa pseudo-histidine phosphotransfer protein，OsPHP1-OsPHP3) 同樣缺乏保守性組胺酸片段，然而目前尚無研究針對 OsPHPs 進行功能性探討。為探討 OsPHP3 的生理功能，本研究首先分析 OsPHP3 的轉錄表現與其選擇性剪切型表現。OsPHP3 具有三個選擇性剪切型，OsPHP3 的轉錄表現與選擇性剪切型表現具有組織專一性，多數組織中以 OsPHP3.1 為主要表現型，OsPHP3.2/ OsPHP3.3 則在根尖專一表現。此外，OsPHP3 的轉錄表現與選擇性剪切表現比例亦受黑暗、細胞分裂素、生長素、高鹽與乾旱等因子調控。OsPHP3 負向調控水稻根系發育，缺失或過量表現 OsPHP3 分別增加或降低植株葉綠素降解、種子根長與癒傷組織地上部再生對於外施細胞分裂素的反應。而 OsPHP3 轉錄表現亦分別增加或降低水稻對高溫與高鹽逆境的耐受性，並影響下游 type-A OsRRs 基因對於外施細胞分裂素、高溫、高鹽與乾旱逆境的反應。以上結果支持 OsPHP3 在水稻細胞分裂素訊息傳導系統中為負向調控角色，並參與水稻生長分化及非生物逆境反應。
並列摘要
Cytokinins are phytohormones that play important roles in plant development and stress tolerance. Cytokinin signaling involves a multiple two-component signaling system. Histidine phosphotransfer proteins (HP) mediate the transfer of phosphoryl groups from membrane-bound receptor, histidine kinases (HK), to response regulators (RR) that trigger the downstream responses. It has been shown that Arabidopsis histidine phosphotransfer protein 6 (AHP6) which lacks the conserved His residue acts as a cytokinin negative regulator. Oryza sativa pseudo-histidine phosphotransfer protein (OsPHP) also lacks the conserved His residue required for phosphotransfer that is found in authentic-HPs. However, studies on the functions of OsPHPs remain limited. In this study, the gene expression and the alternative splicing of OsPHP3 were characterized. OsPHP3 has three alternative splicing variants. The gene expression and the alternative splicing of OsPHP3 are tissue-specifically expressed. RT-PCR analysis indicates that the expression level of OsPHP3.1 is higher than that of OsPHP3.2/ OsPHP3.3 in most tissues. The root tip is the only tissue where the expression level of OsPHP3.2/ OsPHP3.3 is higher than that of OsPHP3.1. The gene expression and the alternative splicing of OsPHP3 are also regulated by dark, cytokinin, auxin, salt and drought. In Osphp3-deficient and OsPHP3-overexpression plants, OsPHP3 negatively regulates root growth and decreases the cytokinin sensitivity which can be reflected in chlorophyll rentention, and shoot callus regeneration experiments. In addition, OsPHP3 enhances survival rate under heat treatment but decreases survival rate under salt treatment. These results indicate that OsPHP3 is a negative regulator of rice cytokinin signaling and plays different roles in heat and salt tolerance in rice.
參考文獻
葉瑞恩 (2015) 水稻Oshk4-2突變體之特性分析. 國立臺灣大學生物資源暨農學院農藝學系碩士論文
Abe, H., Urao, T., Ito, T., Seki, M., Shinozaki, K., and Yamaguchi-Shinozaki, K. (2003). Arabidopsis AtMYC2 (bHLH) and AtMYB2 (MYB) function as transcriptional activators in abscisic acid signaling. Plant Cell 15, 63-78.
Albacete, A., Ghanem, M.E., Martínez-Andújar, C., Acosta, M., Sánchez-Bravo, J., Martínez, V., Lutts, S., Dodd, I.C., and Pérez-Alfocea, F. (2008). Hormonal changes in relation to biomass partitioning and shoot growth impairment in salinized tomato (Solanum lycopersicum L.) plants. Journal of Experimental Botany 59, 4119-4131.
Argueso, C.T., Ferreira, F.J., and Kieber, J.J. (2009). Environmental perception avenues: the interaction of cytokinin and environmental response pathways. Plant, Cell & Environment 32, 1147-1160.
Bauer, J., Reiss, K., Veerabagu, M., Heunemann, M., Harter, K., and Stehle, T. (2013). Structure–function analysis of Arabidopsis thaliana histidine kinase AHK5 bound to its cognate phosphotransfer protein AHP1. Molecular Plant 6, 959-970.