Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

The cloning and characterization of α-galactosidase present during and following germination of tomato (Lycopersicon esculentum Mill.) seed

J. Allan Feurtado, Mitali Banik and J. Derek Bewley
Journal of Experimental Botany
Vol. 52, No. 359 (June 2001), pp. 1239-1249
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/23697029
Page Count: 11
  • Download ($42.00)
  • Cite this Item
The cloning and characterization of α-galactosidase present during and following germination of tomato (Lycopersicon esculentum Mill.) seed
Preview not available

Abstract

α-Galactosidase (EC 3.2.1.22) is present in the embryo, micropylar and lateral endosperm of seeds of tomato during and following germination. Its activity is unchanged even when germination of the seeds is prevented by an osmoticum. It is also present in the developing and mature dry seed. 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 pl of 4.91. The tomato α-galactosidase has a high homology (>62%) at the amino acid level with that of other plant α-galactosidases. 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. Using amino acid alignment and phylogenetic analysis, key amino acids have been identified, and relationships to other α-galactosidases inferred. 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. 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.

Page Thumbnails

  • Thumbnail: Page 
[1239]
    [1239]
  • Thumbnail: Page 
1240
    1240
  • Thumbnail: Page 
1241
    1241
  • Thumbnail: Page 
1242
    1242
  • Thumbnail: Page 
1243
    1243
  • Thumbnail: Page 
1244
    1244
  • Thumbnail: Page 
1245
    1245
  • Thumbnail: Page 
1246
    1246
  • Thumbnail: Page 
1247
    1247
  • Thumbnail: Page 
1248
    1248
  • Thumbnail: Page 
1249
    1249