Cloning of a Cicer arietinum β-galactosidase with pectin-degrading function

The cDNA clone (CanBGal-3) encoding a cell wall pectin-degrading beta-galactosidase (betaIII-Gal) from Cicer arietinum L. cv. Castellana has been identified. The identification was carried out by comparing the deduced amino acid sequences of several isolated chickpea beta-galactosidase clones with the purified betaIII-Gal protein sequence. The expression pattern of the gene corresponding to CanBGal-3 was in concordance with the fluctuations of the enzyme betaIII-Gal in different seedling organs, being specific to elongating organs such as epicotyls and roots. Transformation of Solanum tuberosum plants with the chickpea CanBGal-3 clone indicated that the beta-galactosidase encoded by this clone is a pectin-degrading enzyme. The authors propose an important role for chickpea betaIII-Gal in pectin degradation in cell walls of vegetative organs such as epicotyls and roots. The degradation of galactan carried out by this enzyme may determine structural changes and affect cell wall porosity. It is suggested that the increase in the size of cell wall pores could permit access of other cell wall-modifying enzymes to their substrate.