The role of PopCel1 and PopCel2 in poplar leaf growth and cellulose biosynthesis

Abstract

SummaryPoplar calli transcribed two cellulase (endo-1,4-b-glucanase) genes, PopCel1 and PopCel2, whose mRNAs were differentially located in the growing leaves of poplar during cell wall synthesis. Histochemical and RT-PCR analyses of promoter±GUS fusion gene activities in transgenic poplar demonstrated that PopCel1 promoter-derived GUS activity was localized in the petiole and leaf veins, whereas PopCel2 was con®ned to mesophyll cells and disappeared from the tip during the development of leaves. Autoradiography of the leaf showed that the radioactivity of [ 14 C]sucrose incorporated into cellulose corresponded to the combination of the sucrose-induced tissue-speci®c patterns of PopCel1 and PopCel2. Interestingly, 2,6-dichlorobenzonitrile (DCB) not only inhibited the incorporation of the radioactivity into cellulose, but also repressed the induction of both cellulase genes. Suppression of cellulases by expression of PopCel1 antisense cDNA or cosuppression of PopCel1 mRNA by overexpression of PopCel1 sense cDNA reduced leaf growth. Therefore, we came to the conclusion that PopCel1 and PopCel2 probably function to promote leaf growth in poplar by the endohydrolysis of 1,4-b-glucan.

Poplar Carbohydrate-Active Enzymes. Gene Identification and Expression Analyses

“…Other cellulases in GH9, lacking the membrane-spanning domain, had ESTs that were broadly distributed among poplar tissues (Table III). These cellulases may act on amorphous cellulose in the cell wall and, by doing so, increase cell wall plasticity (Ohmiya et al, 2000(Ohmiya et al, , 2003Park et al, 2003).…”

Nonmotile Cellulose Synthase Subunits Repeatedly Accumulate within Localized Regions at the Plasma Membrane in Arabidopsis Hypocotyl Cells following 2,6-Dichlorobenzonitrile Treatment

“…Montezinos and Delmer, 1980;Edelmann and Fry, 1992;Shedletzky et al, 1992;Suzuki et al, 1992;Vaughn et al, 1996;Nakagawa and Sakurai, 1998;Sabba et al, 1999;Anderson et al, 2002;Himmelspach et al, 2003;Ohmiya et al, 2003;Talbot et al, 2007). However, because the mode of action of the drug is unknown, interpretation of the effects of DCB on cellulose synthesis has been ambiguous because of the possibility of indirect effects.…”

Overexpression of Poplar Cellulase Accelerates Growth and Disturbs the Closing Movements of Leaves in Sengon

“…PopCel1 mRNA was accumulated in transgenic lines 1 to 7 (trg1-trg7), and weak signals were detected in trg4 to trg7. Also, we used an antibody against a 15-amino acid sequence (163-CWERPEDMDTPRNVY-167) for the PaPopCel1 gene product (Ohmiya et al, 2003).…”

“…Poplar cellulase cDNA with 35S promoter has been used in sengon (Paraserianthes falcataria) because the overexpression of poplar cellulase in Arabidopsis and poplar produced more visible effects in their leaves (Ohmiya et al, 2003;Park et al, 2003). In these species, leaf length and width were increased to the same extent as the length of the blade and petiole.…”