赤桉(Eucalyptus camaldulensis)為造紙重要的來源樹種，自紙漿工業轉移至熱帶之後，利用桉樹所生產的紙漿需求大增。本計劃擬定選殖出與纖維素合成相關的基因，研究成果預期將深入瞭解影響紙漿生產的相關基因調控，藉由遺傳工程的輔助，將其轉殖進入優良營養系的赤桉苗木。基因轉殖的赤桉苗木具有潛力應用於紙漿質與量的提升，目前臺灣林業試驗所已在赤桉中分離出數個影響紙漿生產的木質素生合成(lignin biosynthesis) 基因(如4CL1，C4H) ，並經由農桿菌成功地轉殖到不同的赤桉優良營養系，且到達隔離造林試驗階段。所以，此計劃將與臺灣林業試驗所合作，著力於篩選出與纖維素合成相關的纖維素降解酶KORRIGAN (KOR) 基因，再進一步藉定量RT-PCR，原位雜交，蛋白質表達系統等方式，加以探討KOR 基因在赤桉纖維素合成中所扮演的角色。如計畫中有不同成員KOR 基因，將挑選出其中最適合的成員，利用已建立的赤桉基因轉殖體系，藉由農桿菌轉殖以正轉式或反轉式到赤桉。同時，選殖出的KOR 基因也可再轉殖到具有木質素基因，或纖維素合成酶基因(CesA)的赤桉中，由此獲得兼具紙漿生產多價轉基因(gene stacking)林木，這些基因轉殖苗木將會是研究基因調控最佳的材料，也會在全球能源短缺之際，充分瞭解林木碳源配置，提供林木生質能源最有效益的使用方式。 Eucalyptus is one of the most valuable plantation tree due to its extremely fast growth rate, superior fiber and pulping properties. With the increased global demand for short-fiber pulp, we attempt to expand our knowledge to increase the biomass production of Eucalyptus camaldulensis. This study aims to get a better understanding of the mechanism of cellulose synthesis in trees and also would like to meet the demand by the paper and pulp company. Several lignin-related genes have been cloned and transferred into Eucalyptus in TFRI and currently are under field trait stage. Therefore, this work would be initiated with assistance from TFRI to facilitate the breeding program of E. camaldulensis. Therefore, our goals of this plan are: (1) to clone several KORRIGAN (KOR) genes from E. camaldulensis, (2) to characterize their expression pattern by RT-PCR, in situ hybridization, and immunoblotting, (3) to deliver candidate KOR genes in sense orientation into E. camaldulensis via Agrobacterium-mediated gene transformation, and (4) to transfer KOR genes into wood-formation related transgenic E. camaldulensis to generate gene-stacking trees in the future. Those transgenic Eucalyptus trees would offer the potential for the development of sustainable bioenergy and may lead us to a new manufacturing system.
