Acceleration of Cell Growth by Xyloglucan Oligosaccharides in Suspension-Cultured Tobacco Cells

Abstract

The incorporation of xyloglucan oligosaccharide (XXXG) into the walls of suspension-cultured tobacco cells accelerated cell expansion followed by cell division, changed cell shape from cylindrical to spherical, decreased cell size, and caused cell aggregation. Fluorescent XXXG added to the culture medium was found to be incorporated into the surface of the entire wall, where strong incorporation occurred not only on the surface, but also in the interface walls between cells during cell division. Cell expansion was always greater in the transverse direction than in the longitudinal direction and then, immediately, expansion led to cell division in the presence of XXXG; this process might result in the high level of cell aggregation seen in cultured tobacco cells. We concluded that the integration of this oligosaccharide into the walls could accelerate not only cell expansion, but also cell division in cultured cells.

In tobacco BY-2 cells xyloglucan oligosaccharides alter the expression of genes involved in cell wall metabolism, signalling, stress responses, cell division and transcriptional control

“…Changes in fresh weight and the higher and anticipated mitotic index peak with XGO treatment of tobacco BY-2 cells confirm previous reports [30,36] that XGOs stimulate cell division both as individual compounds and as the natural extract containing a mixture of XGOs used here. The fall in mitotic cell size in both control and XGO treated cells during the peak of mitotic index, regaining original size by the end of the culture period, is in line with previous observations in our lab [62].…”

“…The null effect of XGO on cell size is also in agreement with the finding that XGO treatment of BY-2 cells shortens G1 whilst mitotic cell size remained constant [30]. Kaida et al [36] found a reduction in cell size associated with XGO treatment of a different tobacco cell culture system (XD-6 derived from N. tabacum L. var. Xanthi).…”

“…These effects were attributed to a reduction in the molecular weight (MW) of the endogenous XG, resulting in cell wall loosening. Use of fluorescently labelled XXXG demonstrated that the exogenous XGO was incorporated into the cell wall XG and was associated with cell expansion [36]. Transgenic expression of genes encoding XG degradative enzymes such as Aspergillus aculeatus xyloglucanase in poplar [56], Arabidopsis cellulase in poplar [60] or poplar cellulase in Arabidopsis [55], are consistent with the effects of exogenous XGO treatments, confirming an association between XG breakdown and increased cell expansion.…”

“…Treatment of cultured tobacco cells with 0.1-1 mM XXXG resulted in a decrease in cell size, accompanied by a rounding of the cells, but acceleration of cell growth and shortening in cell doubling time resulting in an increase in cell number during the logarithmic phase of culture growth [36]. These effects were attributed to a reduction in the molecular weight (MW) of the endogenous XG, resulting in cell wall loosening.…”

Plant Cell Wall Polymers: Function, Structure and Biological Activity of Their Derivatives

“…Most research in this field highlights their regulatory activity on cell growth and elongation, which relies in the molecular size, distribution, and levels of substituted xylosyl units with galactosyl and fucosyl residues [63]. It has been observed active xyloglucan oligomers (XGOs) accelerate cell elongation in peeled stem segments of Pisum sativum [64], and in suspension-cultured cells of Nicotiana tabacum, expansion led to cell division [65]. On the contrary, treatments with polymeric xyloglucan suppressed cell elongation [64][65], indicating that molecular size is a determinant factor of response specificity.…”