A genomewide analysis of the cinnamyl alcohol dehydrogenase family in sorghum [Sorghum bicolor (L.) Moench] identifies SbCAD2 as the brown midrib6 gene.
The content and composition of the plant cell wall polymer lignin affect plant fitness, carbon sequestration potential, and agro-industrial processing. These characteristics, are heavily influenced by the supply of hydroxycinnamyl alcohol precursors synthesized by the enzyme cinnamyl alcohol dehydrogenase (CAD). In angiosperms, CAD is encoded by a multigene family consisting of members thought to have distinct roles in different stages of plant development. Due to the high sequence similarity among CAD genes, it has been challenging to identify and study the role of the individual genes without a genome sequence. Analysis of the recently released sorghum genome revealed the existence of 14 CAD-like genes at seven genomic locations. Comparisons with maize and rice revealed subtle differences in gene number, arrangement, and expression patterns. Sorghum CAD2 is the predominant CAD involved in lignification based on the phylogenetic relationship with CADs from other species and genetic evidence showing that a set of three allelic brown midrib (bmr) lignin mutants contained mutations in this gene. The impact of the mutations on the structure of the protein was assessed using molecular modeling based on X-ray crystallography data of the closely related Arabidopsis CAD5. The modeling revealed unique changes in structure consistent with the observed phenotypes of the mutants.
Saballos
Ana
A
School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA. saballoa@ufl.edu
Ejeta
Gebisa
G
Sanchez
Emiliano
E
Kang
Chulhee
C
Vermerris
Wilfred
W
D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics*; D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D020224:Expressed Sequence Tags; D015870:Gene Expression; D017343:Genes, Plant; D055106:Genome-Wide Association Study; D008958:Models, Molecular; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D010802:Phylogeny; D011487:Protein Conformation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D045868:Sorghum / Q000201:enzymology* / Q000235:genetics*; D013045:Species Specificity
D017931:DNA Primers; D018744:DNA, Plant; D000429:Alcohol Oxidoreductases; C018656:cinnamyl alcohol dehydrogenase