Changes in carbohydrate composition and α-amylase expression during germination and seedling growth of starch-deficient endosperm mutants of maize

T. E. Young, J. A. Juvik, D. A. DeMason

Research output: Contribution to journalArticle

Abstract

Kernels of 28 different maize (Zea mays L.) genotypes consisting of several inbreds isogenic for the starch-deficient endosperm mutations sugary1 (su1), sugary1; sugary enhancer1 (su1se1), and shrunken2 (sh2) were used to study the effect of these mutations on carbohydrate composition and α- amylase expression during germination and seedling growth in comparison to normal starchy kernels (Su). Sugar (fructose, glucose, sucrose, and maltose), WSP (water-soluble polysaccharide), and insoluble starch contents were determined for endosperm and scutellar tissues for each of the genotypes at four stages of seedling development. While initial levels of endosperm sucrose were higher in the endosperm mutants, they rapidly declined by radicle emergence and remained low thereafter. Mobilization of carbohydrate reserves was most reduced in the sh2 genotypes. Collectively, these factors represent a limited carbon supply for the developing sh2 seedling which may impact seeding vigor. A more significant negative correlation was observed between percentage germination and endosperm sugar content than between percentage germination and scutellar sugar content. High initial levels of endosperm sucrose in the mutants correlate with a severe reduction of α- amylase (EC 3.2.1.1) transcript abundance. The same correlation does not hold for glucose and maltose, as at later stages of germination, levels were significantly higher in the Su genotype while the α-amylase mRNA levels remained high. Furthermore, the ration of α-amylase enzyme activity to transcript abundance was considerable lower in the sh2 aleurone compared to the Su aleurone at radicle emergence. Genotype specific differences in α- amylase gene expression strongly correlate with endosperm sugar content and composition during germination.

Original languageEnglish (US)
Pages (from-to)175-189
Number of pages15
JournalPlant Science
Volume129
Issue number2
DOIs
StatePublished - Nov 21 1997

Keywords

  • Endosperm mutants
  • Germination
  • Metabolic regulation
  • Starch Mobilization
  • Zea mays
  • α-Amylase gene expression

ASJC Scopus subject areas

  • Genetics
  • Agronomy and Crop Science
  • Plant Science

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