The βI-galactosidase of Cicer arietinum is located in thickened cell walls such as those of collenchyma, sclerenchyma and vascular tissue

We report localisation of the chickpea beta I-Gal, a member of the chickpea beta-galactosidase family, which contains at least four members. After generation of specific antibodies, the distribution and cellular immunolocalisation of the protein in different organs and developmental stages of the plant was studied. beta I-Gal protein is much longer than the other chickpea beta-galactosidases because of the presence of a lectin-like domain in the carboxyl terminus of the protein. Western blot experiments indicated that the active beta I-Gal retains this lectin-like domain for its function in the plant. The beta I-Gal protein was mainly detected in cell walls of elongating organs, such as seedling epicotyls and stem internodes. An immunolocation study indicated a very good correlation between the presence of this beta I-galactosidase and cells whose walls are thickening, not only in aged epicotyls and mature internodes in the final phase of elongation, but mostly in cells with a support function, such as collenchyma cells, xylem and phloem fibres and a layer of sclerenchyma cells surrounding the vascular cylinder (perivascular fibres). These results could suggest a function for the beta I-Gal in modification of cell wall polymers, leading to thicker walls than the primary cell walls.