β-(1,4)-Galactan is one of the main side chains of rhamnogalacturonan I. Although the specific function of this polymer has
not been completely established, it has been related to different developmental processes. To study β-(1,4)-galactan function,
we have generated transgenic Arabidopsis plants overproducing chickpea βI-Gal β-galactosidase under the 35S CaMV
promoter (35S::βI-Gal) to reduce galactan side chains in muro. Likewise, an Arabidopsis double loss-of-function mutant for
BGAL1 and BGAL3 Arabidopsis β-galactosidases (bgal1/bgal3) has been obtained to increase galactan levels. The characterization
of these plants has confirmed the role of β-(1,4)-galactan in cell growth, and demonstrated that the turnover of this
pectic side chain occurs during cell elongation, at least in Arabidopsis etiolated hypocotyls and floral stem internodes. The
results indicate that BGAL1 and BGAL3 β-galactosidases act in a coordinate way during cell elongation. In addition, this
work indicates that galactan plays a role in the maintenance of the cell wall architecture during this process. Our results point
to an involvement of the β-(1,4)-galactan in the xyloglucan structure and the interaction between cellulose and xyloglucan
