The Cellulose Synthase Gene Superfamily and Biochemical Functions of Xylem-Specific Cellulose Synthase-Like Genes inPopulus trichocarpa 

Abstract

Wood from forest trees modified for more cellulose or hemicelluloses could be a major feedstock for fuel ethanol. Xylan and glucomannan are the two major hemicelluloses in wood of angiosperms. However, little is known about the genes and gene products involved in the synthesis of these wood polysaccharides. Using Populus trichocarpa as a model angiosperm tree, we report here a systematic analysis in various tissues of the absolute transcript copy numbers of cellulose synthase superfamily genes, the cellulose synthase (CesA) and the hemicellulose-related cellulose synthase-like (Csl) genes. Candidate Csl genes were characterized for biochemical functions in Drosophila Schneider 2 (S2) cells. Of the 48 identified members, 37 were found expressed in various tissues. Seven CesA genes are xylem specific, suggesting gene networks for the synthesis of wood cellulose. Four Csl genes are xylem specific, three of which belong to the CslA subfamily. The more xylem-specific CslA subfamily is represented by three types of members: PtCslA1, PtCslA3, and PtCslA5. They share high sequence homology, but their recombinant proteins produced by the S2 cells exhibited distinct substrate specificity. PtCslA5 had no catalytic activity with the substrates for xylan or glucomannan. PtCslA1 and PtCslA3 encoded mannan synthases, but PtCslA1 further encoded a glucomannan synthase for the synthesis of (1→4)-β-d-glucomannan. The expression of PtCslA1 is most highly xylem specific, suggesting a key role for it in the synthesis of wood glucomannan. The results may help guide further studies to learn about the regulation of cellulose and hemicellulose synthesis in wood.

Complexes with Mixed Primary and Secondary Cellulose Synthases Are Functional in Arabidopsis Plants

“…Phylogenetic analysis reveals that these unique components, in the primary and secondary cell walls, represent distinct gene families that diverged early in the evolution of land plants (Holland et al, 2000;Samuga and Joshi, 2002;Tanaka et al, 2003;Burton et al, 2004;Djerbi et al, 2005;Nairn and Haselkorn, 2005;Ranik and Myburg, 2006;Suzuki et al, 2006;Kumar et al, 2009;Carroll and Specht, 2011).…”

“…Phylogenetic analysis revealed six distinct CESA clades found in seed plants, each corresponding to one of the six required components of the primary and secondary cellulose synthase complexes in Arabidopsis (Holland et al, 2000;Samuga and Joshi, 2002;Tanaka et al, 2003;Burton et al, 2004;Djerbi et al, 2005;Nairn and Haselkorn, 2005;Ranik and Myburg, 2006;Suzuki et al, 2006;Kumar et al, 2009;Carroll and Specht, 2011). The interaction between the different CESA proteins in the primary and secondary rosettes has been characterized previously by coimmunoprecipitation and yeast two-hybrid methods, showing interaction patterns with similarities between primary and secondary CESAs (Taylor et al, 2000;Desprez et al, 2007;Wang et al, 2008;Atanassov et al, 2009;Timmers et al, 2009).…”

The draft genome of the fast-growing non-timber forest species moso bamboo (Phyllostachys heterocycla)

“…We used sequences encoded by the identified CesA or Csl genes in Arabidopsis 25 , poplar 44,45 , rice 46 , maize 26 and sorghum 24 for alignment to those encoded by the gene models of Brachypodium and bamboo by BLASTP with E values under 1 × 10 -10 . Aligned hits with at least 200 amino acids of matched length and over 50% protein sequence identity were considered to be homologs of the CesA or Csl genes.…”

Pattern of Deposition of Cell Wall Polysaccharides and Transcript Abundance of Related Cell Wall Synthesis Genes during Differentiation in Barley Endosperm

“…Later in development heteromannan is present in the starchy endosperm but completely absent from aleurone cell walls. Experiments in which a number of CSLA genes from various plant species have been individually expressed heterologously in either plant or insect systems have shown that these genes encode (gluco)mannan synthases (Dhugga et al, 2004;Liepman et al, 2005Liepman et al, , 2007Suzuki et al, 2006;Doblin et al, 2010). However, this activity has not yet been demonstrated for any members of the cereal-specific clade of the CSLA family (van Erp and Walton, 2009).…”

“…The CslA genes from a broad range of species including Arabidopsis, guar (Cyamopsis tetragonoloba), poplar (Populus trichocarpa), loblolly pine (Pinus taeda), moss (Physcomitrella patens), and rice have been shown to have either mannan or glucomannan synthase activity when heterologously expressed (Dhugga et al, 2004;Liepman et al, 2005Liepman et al, , 2007Suzuki et al, 2006). The expression levels of six known barley CslA genes were followed over the differentiation phase of endosperm development.…”