Perturbation of Wood Cellulose Synthesis Causes Pleiotropic Effects in Transgenic Aspen  

作　　者：Chandrashekhar R Joshi Shivegowda Thammannagowda Takeshi Fujino Ji-Qing Gou Utku Avci Candace H. Haigler Lisa M. McDonnell Shawn D. Mansfield Bemnet Mengesha Nicholas C. Carpita Darby Harris Seth DeBolt Gary F. Peter 

机构地区：[1]Biotechnology Research Center, School of Forest Resources and Environmental Sciences, Michigan Technological University, Houghton, MI 49931, USA [2]Department-of Bioenergy Science and Technology, Chonnam National University, Buk-Gu, Gwangju 500-757, Korea [3]Department of Crop Science, North Carolina State University, 4405 Williams Hall, Raleigh, NC 27695, USA [4]Department of Plant Biology, North Carolina State University, 4405 Williams Hall, Raleigh, NC 27695, USA [5]Department of Wood Science, University of British Columbia, 4030-2424 Main Mall, Vancouver, BC V6T 1Z4, Canada [6]Purdue University, Botany and Plant Pathology, 915 West State Street, West Lafayette, IN 47907, USA [7]Department of Horticulture, N-318 Agricultural Sciences Center, University of Kentucky, Lexington, KY 40546, USA [8]School of Forest Resources and Conservation, 326 Newins-Ziegler Hall, PO Box 110410, University of Florida, Gainesville, FL 32611, USA

出　　处：《Molecular Plant》2011年第2期331-345,共15页分子植物（英文版）

摘　　要：Genetic manipulation of cellulose biosynthesis in trees may provide novel insights into the growth and development of trees. To explore this possibility, the overexpression of an aspen secondary wall-associated cellulose synthase （PtdCesAS） gene was attempted in transgenic aspen （Populus tremuloides L.） and unexpectedly resulted in silencing of the transgene as well as its endogenous counterparts. The main axis of the transgenic aspen plants quickly stopped growing, and weak branches adopted a weeping growth habit. Furthermore, transgenic plants initially developed smaller leaves and a less extensive root system. Secondary xylem （wood） of transgenic aspen plants contained as little as 10% cellulose normalized to dry weight compared to 41% cellulose typically found in normal aspen wood. This massive reduction in cellulose was accompanied by proportional increases in lignin （35%） and non-cellulosic polysaccharides （55%） compared to the 22% lignin and 36% non-cellulosic polysaccharides in control plants. The transgenic stems pro- duced typical collapsed or ＇irregular＇ xylem vessels that had altered secondary wall morphology and contained greatly reduced amounts of crystalline cellulose. These results demonstrate the fundamental role of secondary wall cellulose within the secondary xylem in maintaining the strength and structural integrity required to establish the vertical growth habit in trees.Genetic manipulation of cellulose biosynthesis in trees may provide novel insights into the growth and development of trees. To explore this possibility, the overexpression of an aspen secondary wall-associated cellulose synthase （PtdCesAS） gene was attempted in transgenic aspen （Populus tremuloides L.） and unexpectedly resulted in silencing of the transgene as well as its endogenous counterparts. The main axis of the transgenic aspen plants quickly stopped growing, and weak branches adopted a weeping growth habit. Furthermore, transgenic plants initially developed smaller leaves and a less extensive root system. Secondary xylem （wood） of transgenic aspen plants contained as little as 10% cellulose normalized to dry weight compared to 41% cellulose typically found in normal aspen wood. This massive reduction in cellulose was accompanied by proportional increases in lignin （35%） and non-cellulosic polysaccharides （55%） compared to the 22% lignin and 36% non-cellulosic polysaccharides in control plants. The transgenic stems pro- duced typical collapsed or ＇irregular＇ xylem vessels that had altered secondary wall morphology and contained greatly reduced amounts of crystalline cellulose. These results demonstrate the fundamental role of secondary wall cellulose within the secondary xylem in maintaining the strength and structural integrity required to establish the vertical growth habit in trees.

关 键 词：ASPEN cellulose synthesis transgenic trees xylem development cell wall LIGNIN irregular xylem growth crystallinity. 

分 类 号：S831.2[农业科学—畜牧学] TS102.211[农业科学—畜牧兽医]