The plant cell wall is a dynamic structure whose constant modification is necessary for
plant cells to grow and divide. In the cell walls of chickpea (Cicer arietinum) there are
at least four b-galactosidases, whose presence and location in embryonic axes during
the first 48 h of seed imbibition are discussed in this paper. We examined their roles
as cell wall-modifying enzymes in germinative and/or post-germinative events. At the
start of germination, only bV-Gal, and to a lesser extent bIV-Gal, appear in the axes
before rupture of the testa, suggesting they are related to germination sensu stricto.
Once the testa has broken, the four b-galactosidases are involved in growth and
differentiation of the axes. Immunolocation of the different proteins in axes, which in
part confirms previous results in seedlings and plants, allows assignment of postgerminative
roles to bI-Gal and bIII-Gal as cell wall modifiers in vascular tissue
elements. bIV-Gal and bV-Gal participate in the initial events of germination in which
cell walls are involved: bV-Gal in cell proliferation, detachment of root cap cells and
initial vascular tissue differentiation; both of them in xylem maturation; and bIV-Gal
in thickening of the primary cell wall. Together with other cell wall-modifying
enzymes, such as expansins and XTH, chickpea galactosidases might function in a
sequential order in turnover of the primary cell wall, allowing the elongation of
embryonic axes during seed germination.
