Poplar carbohydrate-active enzymes. Gene identification and expression analyses.
Over 1,600 genes encoding carbohydrate-active enzymes (CAZymes) in the Populus trichocarpa (Torr. & Gray) genome were identified based on sequence homology, annotated, and grouped into families of glycosyltransferases, glycoside hydrolases, carbohydrate esterases, polysaccharide lyases, and expansins. Poplar (Populus spp.) had approximately 1.6 times more CAZyme genes than Arabidopsis (Arabidopsis thaliana). Whereas most families were proportionally increased, xylan and pectin-related families were underrepresented and the GT1 family of secondary metabolite-glycosylating enzymes was overrepresented in poplar. CAZyme gene expression in poplar was analyzed using a collection of 100,000 expressed sequence tags from 17 different tissues and compared to microarray data for poplar and Arabidopsis. Expression of genes involved in pectin and hemicellulose metabolism was detected in all tissues, indicating a constant maintenance of transcripts encoding enzymes remodeling the cell wall matrix. The most abundant transcripts encoded sucrose synthases that were specifically expressed in wood-forming tissues along with cellulose synthase and homologs of KORRIGAN and ELP1. Woody tissues were the richest source of various other CAZyme transcripts, demonstrating the importance of this group of enzymes for xylogenesis. In contrast, there was little expression of genes related to starch metabolism during wood formation, consistent with the preferential flux of carbon to cell wall biosynthesis. Seasonally dormant meristems of poplar showed a high prevalence of transcripts related to starch metabolism and surprisingly retained transcripts of some cell wall synthesis enzymes. The data showed profound changes in CAZyme transcriptomes in different poplar tissues and pointed to some key differences in CAZyme genes and their regulation between herbaceous and woody plants.
Geisler-Lee
Jane
J
Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, Sweden.
Geisler
Matt
M
Coutinho
Pedro M
PM
Segerman
Bo
B
Nishikubo
Nobuyuki
N
Takahashi
Junko
J
Aspeborg
Henrik
H
Djerbi
Soraya
S
Master
Emma
E
Andersson-Gunnerås
Sara
S
Sundberg
Björn
B
Karpinski
Stanislaw
S
Teeri
Tuula T
TT
Kleczkowski
Leszek A
LA
Henrissat
Bernard
B
Mellerowicz
Ewa J
EJ
D017360:Arabidopsis / Q000235:genetics; D050260:Carbohydrate Metabolism; D002244:Carbon / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D004798:Enzymes / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D014644:Genetic Variation; D018745:Genome, Plant; D008954:Models, Biological; D005810:Multigene Family; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D032107:Populus / Q000201:enzymology* / Q000235:genetics*; D018749:RNA, Plant / Q000378:metabolism; D012621:Seasons; D013213:Starch / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism
D004798:Enzymes; D010940:Plant Proteins; D018749:RNA, Plant; D013395:Sucrose; D002244:Carbon; D013213:Starch