14 research outputs found
Downregulation of Cinnamyl-Alcohol Dehydrogenase in Switchgrass by RNA Silencing Results in Enhanced Glucose Release after Cellulase Treatment
Cinnamyl alcohol dehydrogenase (CAD) catalyzes the last step in monolignol biosynthesis and genetic evidence indicates CAD deficiency in grasses both decreases overall lignin, alters lignin structure and increases enzymatic recovery of sugars. To ascertain the effect of CAD downregulation in switchgrass, RNA mediated silencing of CAD was induced through Agrobacterium mediated transformation of cv. “Alamo” with an inverted repeat construct containing a fragment derived from the coding sequence of PviCAD2. The resulting primary transformants accumulated less CAD RNA transcript and protein than control transformants and were demonstrated to be stably transformed with between 1 and 5 copies of the T-DNA. CAD activity against coniferaldehyde, and sinapaldehyde in stems of silenced lines was significantly reduced as was overall lignin and cutin. Glucose release from ground samples pretreated with ammonium hydroxide and digested with cellulases was greater than in control transformants. When stained with the lignin and cutin specific stain phloroglucinol-HCl the staining intensity of one line indicated greater incorporation of hydroxycinnamyl aldehydes in the lignin
Enzymic Synthesis of Lignin Precursors Comparison of Cinnamoyl-CoA Reductase and Cinnamyl Alcohol: NADP+ Dehydrogenase from Spruce (Picea abies L.) and Soybean (Glycine max L.)
The stereospecificity of the ferrous-ion-dependent alcohol dehydrogenase from Zymomonas mobilis
Enzymatic and biochemical alterations in relation to lignin deposition at different growth stages of tall fescue
Enzymic Synthesis of Lignin Precursors. Purification and Properties of a Cinnamoyl-CoA: NADPH Reductase from Cell Suspension Cultures of Soybean (Glycine max)
Purification and characterization of a malic enzyme from the ruminal bacterium Streptococcus bovis ATCC 15352 and cloning and sequencing of its gene
cDNA cloning sequence analysis and seasonal expression of lignin-bispecific caffeic acid/5-hydroxyferulic acid O-methyltransferase of aspen
A cDNA clone (Ptomt1) encoding a lignin-bispecific O-methyltransferase (OMT) was isolated by immunological screening of a λgt11 expression library prepared from mRNA of developing secondary xylem of aspen (Populus tremuloides). Nucleotide sequence analysis of Ptomt1 revealed an open reading frame of 1095 bp which encodes a polypeptide with a predicted molecular weight of 39 802, corresponding well with the size of the OMT polypeptide estimated by SDS-PAGE. Authenticity of Ptomt1 was demonstrated in part by detection of OMT activity and protein in extracts of Escherichia coli cultures transformed with a plasmid construct containing Ptomt1. In addition, peptides produced from a proteolytic digest of purified OMT and sequenced by automated Edman degradation matched to portions of the deduced amino acid sequence of Ptomt1. Comparison of this sequence to amino acid sequences of OMTs of diverse species identified regions of similarity which probably contribute to the binding site of S-adenosyl-L-methionine. Tissue-specific expression was demonstrated by northern analysis which showed that Ptomt1 hybridized to a 1.7 kb transcript from aspen developing secondary xylem and by tissue printing of aspen stems in which only the outer layer of xylem bound the antibody. A biphasic pattern of gene expression and enzyme activity for OMT was observed from xylem samples of aspen during the growing season which suggests linkage between gene expression for a monolignol biosynthetic enzyme and seasonal regulation of xylem differentiation in woody plants. © 1991 Kluwer Academic Publishers