Starch biosynthesis by AGPase, but not starch degradation by BAM1/3 and SEX1, is rate-limiting for CO 2 -regulated stomatal movements under short-day conditions

FEBS Lett. 2018 Aug;592(16):2739-2759. doi: 10.1002/1873-3468.13198. Epub 2018 Aug 10.


Starch in guard cells functions in osmoregulation during stomatal movements. Starch metabolism is controlled by the circadian clock. We investigated the role of starch metabolism in stomatal responses to CO2 under different photoperiodic conditions. Guard cell starch levels correlate with low/high [CO2 ] exposure. Starch biosynthesis-deficient AGPase (ADG1) mutants but, unexpectedly, not the starch degradation-deficient BAM1, BAM3, and SEX1 mutants alone, are rate-limiting for stomatal conductance responses to [CO2 ]-shifts. Interestingly, AGPase is rate-limiting solely under short- but not long-day conditions. These findings suggest a model of enhanced AGPase activity in guard cells under short days such that starch biosynthesis becomes rate-limiting for CO2 -induced stomatal closing.

Keywords: Arabidopsis; gas exchange; guard cell; photoperiod; starch degradation; starch synthesis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis / physiology*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Carbon Dioxide / metabolism*
  • Gene Expression Regulation, Plant
  • Glucose-1-Phosphate Adenylyltransferase / genetics
  • Glucose-1-Phosphate Adenylyltransferase / metabolism*
  • Monosaccharide Transport Proteins / metabolism
  • Mutation
  • Photoperiod
  • Plant Leaves
  • Plant Stomata / genetics
  • Plant Stomata / metabolism
  • Plant Stomata / physiology
  • Protein-Serine-Threonine Kinases / metabolism
  • Starch / biosynthesis*


  • Arabidopsis Proteins
  • Monosaccharide Transport Proteins
  • Carbon Dioxide
  • Starch
  • BAM1 protein, Arabidopsis
  • BAM2 protein, Arabidopsis
  • BAM3 protein, Arabidopsis
  • Protein-Serine-Threonine Kinases
  • ADP-glucose pyrophosphorylase, Arabidopsis
  • Glucose-1-Phosphate Adenylyltransferase
  • SEX1 protein, Arabidopsis

Associated data

  • GENBANK/At5g48300
  • GENBANK/AT1G10760
  • GENBANK/AT3G23920
  • GENBANK/AT4G17090