Genome-Wide Characterization of the Lignification Toolbox in Arabidopsis  

Abstract

Lignin, one of the most abundant terrestrial biopolymers, is indispensable for plant structure and defense. With the availability of the full genome sequence, large collections of insertion mutants, and functional genomics tools, Arabidopsis constitutes an excellent model system to profoundly unravel the monolignol biosynthetic pathway. In a genome-wide bioinformatics survey of the Arabidopsis genome, 34 candidate genes were annotated that encode genes homologous to the 10 presently known enzymes of the monolignol biosynthesis pathway, nine of which have not been described before. By combining evolutionary analysis of these 10 gene families with in silico promoter analysis and expression data (from a reverse transcription-polymerase chain reaction analysis on an extensive tissue panel, mining of expressed sequence tags from publicly available resources, and assembling expression data from literature), 12 genes could be pinpointed as the most likely candidates for a role in vascular lignification. Furthermore, a possible novel link was detected between the presence of the AC regulatory promoter element and the biosynthesis of G lignin during vascular development. Together, these data describe the full complement of monolignol biosynthesis genes in Arabidopsis, provide a unified nomenclature, and serve as a basis for further functional studies.

Tracking Monolignols during Wood Development in Lodgepole Pine

“…In diverse species, phenylpropanoid biosynthetic enzymes such as PAL have been localized in the cytosol (Smith et al, 1994;Takabe et al, 2001), while cytochrome P450 enzymes such as C4H and p-coumarate-3-hydroxylase have been shown to be associated with the endoplasmic reticulum (Ro et al, 2001;Raes et al, 2003). The location of these enzymes suggests that monolignols are synthesized in the cytosolic compartment and, to be transported to the apoplast, must cross the plasma membrane.…”

Internode structure and cell wall composition in maturing tillers of switchgrass (Panicum virgatum. L)

“…Lignin is an important antinutritive in forage crops and decreasing lignin content through breeding significantly enhances digestibility as determined through invitro dry matter digestibility (IVDMD) protocols Chen et al, 2002) as well as cattle weight gain (Anderson et al, 1988). Lignin is a polymer of cross-linked phenolics derived from the phenylpropanoid pathway Raes et al, 2003), and is an integral part of the secondary cell walls of plants. There are several key enzymes in this complex pathway (Dixon et al, 2001) and contribute to the overall lignin content and signature for a given species (Raes et al, 2003).…”

“…Lignin is a polymer of cross-linked phenolics derived from the phenylpropanoid pathway Raes et al, 2003), and is an integral part of the secondary cell walls of plants. There are several key enzymes in this complex pathway (Dixon et al, 2001) and contribute to the overall lignin content and signature for a given species (Raes et al, 2003). For example, natural mutations in the genes (Casler et al, 2002;Cardinal et al, 2003;Pedersen et al, 2005) or antisense suppression (Anterola and Lewis, 2002;Peter and Neale, 2004) of enzymes controlling phenylpropanoid metabolism can alter plant anatomy, lignification and impact plant fitness.…”

Repression of Lignin Synthesis in Rice by C4H and 4CL Using RNAi

“…Amongst the inhibition of 4CL gene expression will reduce the synthesis of H, G and S-type lignin. Therefore, genetic engineering can be utilized to suppress C4H and 4CL gene expressions and consequently reduce lignin content in the straw of gramineous plants [4], [5].…”