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Perturbation of Wood cellulose synthesis Causes Pleiotropic Effects in Transgenic Aspen

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Molecular Plant 2011年第2期4卷 331-345页

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

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.

Disruption of Secondary Wall cellulose Biosynthesis Alters Cadmium Translocation and Tolerance in Rice Plants

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Molecular Plant 2013年第3期6卷 768-780页

作者： Xue-Qin Song Li-Feng Liu Yi-Jun Jiang Bao-Cai Zhang Ya-Ping Gao Xiang-Ling Liu Qing-Shan Lin Hong-Qing Ling Yi-Hua Zhou State Key Laboratory of Plant Genomics Institute of Genetics and Developmental Biology Chinese Academy of Sciences Beijing 100101 China Rice Research Institute Guangdong Academy of Agricultural Sciences Guangzhou 510640 China State Key Laboratory of Plant Cell and Chromosome Engineering Institute of Genetics and Developmental Biology Chinese Academy of Sciences Beijing 100101 China

Tricheary elements （TEs）, wrapped by secondary cell wall, play essential roles in water, mineral, and nutrient transduction. Cadmium （Cd） is a toxic heavy metal that is absorbed by roots and transported to shoot, leaves, and grains through vascular systems in plants. As rice is a major source of Cd intake, many efforts have been made to establish ＇low- Cd rice＇. However, no links have been found between cellulose biosynthesis and cadmium accumulation. We report here a rice brittle culm13 mutant, resulting from a novel missense mutation （G101K） in the N-terminus of cellulose synthase subunit 9 （CESA9）. Except for the abnormal mechanical strength, the mutant plants are morphologically indistinguishable from the wild-type plants. Transmission electron microscopy （TEM） and chemical analyses showed a slight reduction in secondary wall thickness and 22% decrease in cellulose content in bc13 plants. Moreover, this mutation unexpectedly confers the mutant plants Cd tolerance due to less Cd accumulation in leaves. Expression analysis of the genes required for Cd uptake and transport revealed complicated alterations after applying Cd to wild-type and bc13. The mutants were further found to have altered vascular structure. More importantly, Cd concentration in the xylem saps from the bc13 plants was significantly lower than that from the wild-type. Combining the analyses of CESA9 gene expression and Cd content retention in the cell-wall residues, we conclude that CESA9^G101K mutation alters cell-wall properties in the conducting tissues, which consequently affects Cd translocation efficiency that largely contributes to the low Cd accumulation in the mutant plants.

关键词： secondary cell wall cellulose synthesis vascular system cadmium accumulation tricheary elements rice.

PtrCel9A6, an Endo-l,4-β-Glucanase, Is Required for Cell Wall Formation during Xylem Differentiation in Populus

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Molecular Plant 2013年第6期6卷 1904-1917页

作者： Liangliang Yu Jiayan Sun Laigeng Li National Key Laboratory of Plant Molecular Genetics/CAS Key Laboratory of Synthetic Biology Institute of Plant Physiology and Ecology Shanghai Institutes for Biological Sciences Chinese Academy of Sciences 300 Fenglin Road Shanghai 200032 China

ABSTRACT Endo-l,4-β-glucanases （EGases） are involved in many aspects of plant growth. Our previous study found that an EGase, PtrCel9A6, is specifically expressed in differentiating xylem cells during Populus secondary growth. In this study, the xylem-specific PtrCel9A6 was characterized for its role in xylem differentiation. The EGase is localized on the plasma membrane with catalytic domain toward the outside cell wall, hydrolyzing amorphous cellulose. Suppression of PtrCel9A6 expression caused secondary cell wall defects in xylem cells and significant cellulose reduction in Populus. Heterologous expression of PtrCelgA6 in Arabidopsis enhanced plant growth as well as increased fiber cell length. In addition, introduction of PtrCel9A6 into Arabidopsis resulted in male sterility due to defects in anther dehiscence. Together, these results demonstrate that PtrCel9A6 plays a critical role in remodeling the 1,4-β-glucan chains in the wall matrix and is required for cell wall thickening during Populus xylem differentiation.

关键词： endo-l,4-β-glucanase cell wall cellulose synthesis cell wall thickening Populus.

Gene expression and metabolite profiles of cotton fiber during cell elongation and secondary cell wall synthesis

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Cell Research 2007年第5期17卷 422-434页

作者： Jin-Ying Gou1,2,3 Ling-Jian Wang1,2 Shuang-Ping Chen4 Wen-Li Hu1,2 Xiao-Ya Chen1,2 1 National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China 2 CAS Center of Shanghai Chenshan Botanical Garden, 300 Fenglin Road, Shanghai 200032, China 3 Graduate School of Chinese Academy of Sciences, Shanghai 200032, China 4 Department of Computer Science and Technology, University of Science and Technology of China, Hefei 230026, China NationalKeyLaboratoryofPlantMolecularGenetics InstituteofPlantPhysiologyandEcologyShanghaiInstitutesforBiologicalSciencesChineseAcademyofSciences300FenglinRoadShanghai200032China

Cotton fibers elongate rapidly after initiation of elongation, eventually leading to the deposit of a large amount ofcellulose. To reveal features of cotton fiber cells at the fast elongation and the secondary cell wall synthesis stages, wecompared the respective transcriptomes and metabolite profiles. Comparative analysis of transcriptomes by cDNA arrayidentified 633 genes that were differentially regulated during fiber development. Principal component analysis (PCA)using expressed genes as variables divided fiber samples into four groups, which are diagnostic of developmental *** grouping results are also found if we use non-polar or polar metabolites as variables for PCA of developingfibers. Auxin signaling, wall-loosening and lipid metabolism are highly active during fiber elongation, whereas cellulosebiosynthesis is predominant and many other metabolic pathways are downregulated at the secondary cell wall synthesisstage. Transcript and metabolite profiles and enzyme activities are consistent in demonstrating a specialization process ofcotton fiber development toward cellulose synthesis. These data demonstrate that cotton fiber cell at a certain stage has itsown unique feature, and developmental stages of cotton fiber cells can be distinguished by their transcript and metaboliteprofiles. During the secondary cell wall synthesis stage, metabolic pathways are streamed into cellulose synthesis.

关键词： cotton fiber transcriptome metabolite profile auxin cell elongation cellulose synthesis

Two Types of cellulose Synthase Complexes are Involved in the Cell Wall for Mation of the Differentiating Xylem in Populu

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Two Types of Cellulose Synthase Complexes are Involved in th...