Skip to main content
Plant Physiology logoLink to Plant Physiology
. 1984 Feb;74(2):324–328. doi: 10.1104/pp.74.2.324

A Debranching Enzyme Deficiency in Endosperms of the Sugary-1 Mutants of Maize 1

David Pan 1, Oliver E Nelson 1
PMCID: PMC1066677  PMID: 16663417

Abstract

Many of the sugary-1 mutants of maize (Zea mays L.) have the highly branched water-soluble polysaccharide, phytoglycogen, in quantities equal to or greater than starch as an endosperm storage product in mature seeds. We find that all sugary mutants investigated are deficient in debranching enzyme [α-(1, 6)-glucosidase] activity in endosperm tissue 23 days postpollination and suggest that this deficiency is the primary biochemical lesion leading to phytoglycogen accumulation in sugary endosperms. This would indicate that the amylopectin component of starch depends on an equilibrium between the activities of branching enzymes introducing α-1,6 branch points into the linear α-1,4 glucans and debranching enzymes. The debranching enzyme activities from nonsugary endosperms can be separated into three peaks on a hydroxyapatite column. The sugary endosperm extracts lack one of these peaks of activity while the other two fractions have much reduced activity. The embryos of developing seeds (23 days after pollination) from both sugary and nonsugary genotypes have equivalent debranching activity. The debranching enzyme activity of developing endosperms is proportional to the number of copies (0 to 3) of the nonmutant (Su) allele present suggesting that the Su allele may be the structural gene for this debranching enzyme, although this is not definitive. This identification of debranching enzyme activity as being the biochemical lesion in sugary endosperms is consistent with several previous observations on the mutant.

Full text

PDF
324

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Akatsuka T., Nelson O. E. Starch granule-bound adenosine diphosphate glucose-starch glucosyltransferases of maize seeds. J Biol Chem. 1966 May 25;241(10):2280–2285. [PubMed] [Google Scholar]
  2. Boyer C. D., Preiss J. Evidence for independent genetic control of the multiple forms of maize endosperm branching enzymes and starch synthases. Plant Physiol. 1981 Jun;67(6):1141–1145. doi: 10.1104/pp.67.6.1141. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Boyer C. D., Preiss J. Multiple forms of starch branching enzyme of maize: evidence for independent genetic control. Biochem Biophys Res Commun. 1978 Jan 13;80(1):169–175. doi: 10.1016/0006-291x(78)91119-1. [DOI] [PubMed] [Google Scholar]
  4. Chourey P. S., Nelson O. E. The enzymatic deficiency conditioned by the shrunken-1 mutations in maize. Biochem Genet. 1976 Dec;14(11-12):1041–1055. doi: 10.1007/BF00485135. [DOI] [PubMed] [Google Scholar]
  5. ERLANDER S. R. A proposed mechanism for the synthesis of starch from glycogen. Enzymologia. 1958 Jun 30;19(5):273–283. [PubMed] [Google Scholar]
  6. Hannah L. C., Tuschall D. M., Mans R. J. Multiple forms of maize endosperm adp-glucose pyrophosphorylase and their control by shrunken-2 and brittle-2. Genetics. 1980 Aug;95(4):961–970. doi: 10.1093/genetics/95.4.961. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
  8. Lee E. Y., Marshall J. J., Whelan W. J. The substrate specificity of amylopectin-debranching enzymes from sweet corn. Arch Biochem Biophys. 1971 Apr;143(2):365–374. doi: 10.1016/0003-9861(71)90223-2. [DOI] [PubMed] [Google Scholar]
  9. Nelson O. E., Chourey P. S., Chang M. T. Nucleoside Diphosphate Sugar-Starch Glucosyl Transferase Activity of wx Starch Granules. Plant Physiol. 1978 Sep;62(3):383–386. doi: 10.1104/pp.62.3.383. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Preiss J., Lammel C., Sabraw A. A unique adenosine diphosphoglucose pyrophosphorylase associated with maize embryo tissue. Plant Physiol. 1971 Jan;47(1):104–108. doi: 10.1104/pp.47.1.104. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Plant Physiology are provided here courtesy of Oxford University Press

RESOURCES