2017-07-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/681962摘要：由於全球氣候變遷的影響導致許多森林生態系統面臨嚴重乾旱的脅迫，林木樹種大規模的因為 乾旱而死亡的現象在全球各地陸續出現報導，導致森林面積快速萎縮而影響生態環境、耕地面 積、以及木材生產來源的下降，使得研究林木樹種在乾旱脅迫下的耐旱機制更為急迫需要。木 質部是植物體中提供水分運輸的組織，植物透過改變木質部中木質素的含量來適應乾旱脅迫， 然而木質素在乾旱脅迫下的合成機制尚不清楚。轉錄因子目前已經知道在各種非生物的脅迫下 為在植物內調控抵抗的機制，但是由於植物體中有非常多的轉錄因子，導致鑑定出乾旱誘導的 轉錄因子有相當的難度。次世代定序的技術近年來日漸成熟，而提供了一個良好的平台來分析 植物體中的轉錄組，我們將使用次世代定序來鑑定出乾旱脅迫下差異表現的木質素單體合成基 因以及轉錄因子，透過酵母單雜交篩選系統，構建出一個五層的階層轉錄調控網路。我們將使 用染色質免疫共沉澱技術以及轉錄因子調控能力測試技術在木質部原生質體中驗證這個階層轉 錄調控網路。目前所知，轉錄調控也和組蛋白修飾有關, 而其中組蛋白H3K9上的乙&#37232;化是活化基因轉錄的作用，我們將從調控網路中選取關鍵的轉錄因子，和鑑定各種木質素基因啟動子上的乙&#37232;化，大量表現這些轉錄因子在林木樹種中而產生新的耐旱樹種。本計畫將使用木本植物中的模式植物毛果楊進行研究。<br> Abstract: In the past decades, global warming caused extreme weather including severe drought, which destroyed many forestry ecosystem in Asia, North America, Europe and Africa. Numerous forest withered due to low rainfall leading to less wood production and decreased agriculture area. Studying the response of woody plants under drought stress can provide information for scientists to generate drought tolerant plants. Xylem exerts water transportation throughout the whole plants. Previous showed that plants changed the lignin contents in xylem to adapt drought stress, however, little is known of the regulation of lignin biosynthesis under drought stress. In this proposed project, we will use Populus trichocarpa as a model system to study the regulation of lignin biosynthesis under drought stress. Using RNA-seq and ChIP-seq, we previously identified several monolignol biosynthesis gene expression were regulated during drought, which was also related to the histone acetylation marker, H3K9ac. Histone acetyltransferase (HAT) and histone deacetylase (HDAC) control the level of histone acetylation through the protein-protein interaction with transcription factors (TFs). We will construct a TF library containing all xylem preferentially expressed TFs for Y1H to screen for the TF directly regulating the drought-related monolignol biosynthesis genes. To verify the regulation of these TFs, we will use our recently developed SDX protoplasts system to test the direct binding of these TFs to the promoters of these monolignol genes and their transactivation ability. Comparing to the protein sequence of HAT and HDAC in Arabidopsis, we identified total 44 orthologs in P. trichocarpa, and these 44 genes will be used for Y2H to identify the protein-protein interaction between HAT/HDAC and the verified TFs. The regulatory mechanism will be revealed by the transgenics overexpressing the TFs identified from both Y1H and Y2H. This research will provide accurate information for gene modification to improve the drought tolerance of forest ecosystem.毛果楊乾旱轉錄調控網路轉錄因子Populus trichocarpadroughttranscriptional regulatory networktranscription factor