Populus tremula x tremuloides

Similar to Arabidopsis, 10 different CesA genes were first identified (Djerbi et al. 2004) by analyzing EST sequences in a collection of tissue specific cDNA libraries of poplars (Sterky et al. 2004). These CesA genes were named PttCesA (for Populus tremula x tremuloides, Ptt) followed by a number (1-9) reflecting... 

Master E., Rudsander U., Zhou W., Henriksson H., Divne C., Denman S., Wilson D., and Teeri T.T. 2004. Recombinant expression and enzymatic characterization of PttCel9A, a KOR homologue from Populus tremula x tremuloides. Biochemistry 43 10080-10089. 

Ohlsson A.B., Djerbi S., Winzell A., Bessueille L., StSldal L., Li X.G., Blomqvist K., Bulone V, Teeri T.T., and Berglimd T. 2006. Cell suspension cultures of Populus tremula x tremuloides exhibit a high level of cellulose synthase gene expression that coincides with increased in vitro cellulose synthase activity. Protoplasma, 228(4) 221-229. in press. 

Rajangam A.S., Aspeborg H., Arvestad L., Pansri R, Tan T.-C., Hober S., Blomqvist K., Divne C., Bulone V., Sundberg B., Mellerowicz E., and Teeri T.T. 2006. PttMAP20, a novel microtubule-associated protein in the secondary cell wall forming tissues of Populus tremula x tremuloides. Submitted for publication. 

In the best case, up to 1 mg of cellulose could be synthesized (Lai Kee Him et al. 2002). These experiments have allowed a complete characterization of the in vitro cellulose using physical and chemical techniques, but callose was still the major product in the reaction mixture (Lai Kee Him et al. 2002). Thus, it remains now to improve the in vitro procedure to isolate higher amounts of complexes composed of cellulose and synthesizing enzymes in order to be able to identify the different proteins required for cellulose polymerization. Promising models for such improvement are the recently established cell suspension cultures of hybrid aspen (Populus tremula x tremuloides) (Ohlsson et al. 2006). The first... 

Figure 6-4. Relative abundance of the ten different PttCesA clones in the different tissue specific EST libraries from Populus tremula (L.) x tremuloides (Michx.). Data from Djerbi et al. 2003 See Color Plate of this figure beginning on page 355)...

Figure 6-5. (A) Microarray expression ratios of the different CesA genes from Populus tremula (L.) x tremuloides (Michx.) in xylem versus phloem and in tension wood versus xylem (twl 1/contl 1) (data from Djerbi et al. 2003). (B) Relative expression levels of PttCesA s from Populus tremula (L.) x tremuloides (Michx.) normalized to the putative ubiquitin protein ligase-1 (ubiquitin) in phloem, xylem, tension wood (bent 11 days, twll) and xylem (unbent control, contl 1). Data from Djerbi et al. 2003...

Figure 6-6. Expression profiles of selected genes encoding enzymes influencing cellulose synthesis in Populus tremula (L.) x tremuloides (Michx.) (data from Hertzberg et al. 2001). The tissues sampled were Ph, phloem A, cambium B, early expansion C, late expansion, early secondary wall synthesis D, secondary wall synthesis and E, programmed cell death. In each zone, the expression level of...

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