Beta galactosidases in Arabidopsis and tomato - a mini review

Beta galactosidases (BGALs) are glycosyl hydrolases that remove terminal β-D-galactosyl residues from β-D-galactosides. There are 17 predicted BGAL genes in the genomes of both Arabidopsis (BGAL1-17) and tomato (TBG1-17). All tested BGALs have BGAL activity but their distinct expression profiles and ancient phylogenetic separation indicates that these enzymes fulfil diverse, non-redundant roles in plant biology. The majority of these BGALs are predicted to have signal peptide and thought to act during cell wall-related biological processes. Interestingly, deletion of BGAL6 and BGAL10 in Arabidopsis causes reduced mucilage release during seed imbibition and shorter siliques respectively, whereas TBG4 depletion by RNAi decreases in fruit softening in tomato. The majority of plant BGALs remain to be characterized.