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Abstract Detail


Cell Walls

Joshi, Chandrashekhar P. [1], Liu, Yunxia [2], Fujino, Takeshi [1], Thammannagowda, Shiv [1], Xu, Fuyu [1].

Spatiotemporal regulation of three coordinately expressed poplar cellulose synthase genes involved in xylem development and tension wood formation.

Cellulose is the major component of plant cell walls. In Arabidopsis, a family of cellulose synthase (CesA) genes is identified that plays pivotal roles in cellulose biosynthesis. Based on mutant-complementation analysis, three distinct CesA genes (AtCesA1, AtCesA3 and AtCesA6) are discovered to be essential for primary cell wall development and the other three distinct CesA genes (AtCesA4, AtCesA7 and AtCesA8) are necessary for secondary cell wall development. Recent completion of poplar genome sequence has permitted a comparison of CesA orthologs from Arabidopsis and poplar. We have characterized three poplar secondary wall associated CesAs, PtrCesA1-PtrCesA3 that are orthologous to AtCesA8, 7 and 4, respectively. We also discovered that these three CesAs are significantly and coordinately upregulated during xylem development as well as during tension wood formation where cellulose-rich tension wood fibers are produced. Our long-term goal is to identify key transcription factors that act as genetic master switches in the spatiotemporal regulation of cellulose synthesis in poplar trees. Based on poplar genome sequence, we cloned the upstream promoter regions of PtrCesA1-PtrCesA3 and prepared GUS fusion constructs to explore xylem-specific and tension stress responsive expression of GUS gene. Agrobacterium mediated transformation of tobacco and poplar resulted in transgenic plants carrying these constructs. Work with unidirectional promoter deletions is in progress and we already identified two cis-acting elements involved in wood formation in PtrCesA1 promoter. These studies will ultimately lead to identification and manipulation of transcription factors that will simultaneously regulate cellulose production in woody tissues of economically important trees.


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1 - Michigan Technological University, SFRES
2 - Michigan Technological University, SFRES, 1400 Townsend Drive, Houghton, MI, 49931, USA

Keywords:
Cellulose
poplar
CesA
promoter
tree.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P17007
Abstract ID:172


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