A starch-accumulating mutant of Arabidopsis thaliana deficient in a chloroplastic starch-hydrolysing enzyme

Plant J. 1998 Aug;15(3):357-65. doi: 10.1046/j.1365-313x.1998.00213.x.


The aim of this work was to identify enzymes that participate in the degradation of transitory starch in Arabidopsis. A mutant line was isolated by screening leaves at the end of the night for the presence of starch. The mutant had a higher starch content than the wild-type throughout the diurnal cycle. This accumulation was due to a reduction in starch breakdown, leading to an imbalance between the rates of synthesis and degradation. No reduction in the activity of endo-amylase (alpha-amylase), beta-amylase, starch phosphorylase, maltase, pullulanase or D-enzyme could be detected in crude extracts of leaves of the mutant. However, native PAGE in gels containing amylopectin revealed that a starch-hydrolysing activity, putatively identified as an endo-amylase and present in wild-type chloroplasts, was absent or appreciably reduced in the mutant. This is the first time that a specific enzyme required for starch degradation has been identified in leaves.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amylases / deficiency*
  • Amylases / genetics
  • Amylases / isolation & purification
  • Arabidopsis / enzymology
  • Arabidopsis / genetics*
  • Arabidopsis / metabolism*
  • Chloroplasts / enzymology
  • Circadian Rhythm
  • Electrophoresis, Polyacrylamide Gel
  • Hydrolysis
  • Mutation*
  • Starch / metabolism*


  • Starch
  • Amylases