Α‐Galactosidase, tomato seed, germination, gene expression. From Northern hybridization studies it is evident that α‐galactosidase transcripts are present in the lateral and micropylar endosperm during and following germination, and also to a lesser extent in the embryo. Southern hybridization analyses show that the enzyme is derived from a single gene (for which a partial sequence has been obtained) and yet there are at least three different isoforms within the seed post‐translational modifications are thus presumed to occur. Using amino acid alignment and phylogenetic analysis, key amino acids have been identified, and relationships to other α‐galactosidases inferred.

A hydrophobic signal peptide region is identified which is indicative that the enzyme enters the lumen of the endoplasmic reticulum during its translation, prior to its export to the protein body or cell wall, the presumed sites of its substrates. The tomato α‐galactosidase has a high homology (>62%) at the amino acid level with that of other plant α‐galactosidases. A cDNA clone for tomato seed α‐galactosidase ( LeaGal) has been isolated and the characteristics of the protein deduced the predicted molecular mass of the mature enzyme is 39.8 kDa, with a pI of 4.91. It is also present in the developing and mature dry seed. Its activity is unchanged even when germination of the seeds is prevented by an osmoticum.

Α‐Galactosidase (EC 3.2.1.22) is present in the embryo, micropylar and lateral endosperm of seeds of tomato during and following germination.

Clone x to seeds before sprout