Decrease in leaf sucrose synthesis leads to increased leaf starch turnover and decreased RuBP regeneration-limited photosynthesis but not Rubisco-limited photosynthesis in Arabidopsis null mutants of SPSA1

Jindong Sun, Jisen Zhang, Clayton T. Larue, Steven C. Huber

Research output: Contribution to journalArticlepeer-review

Abstract

We investigated the individual effect of null mutations of each of the four sucrose-phosphate synthase (SPS) genes in Arabidopsis (SPSA1, SPSA2, SPSB and SPSC) on photosynthesis and carbon partitioning. Null mutants spsa1 and spsc led to decreases in maximum SPS activity in leaves by 80 and 13%, respectively, whereas null mutants spsa2 and spsb had no significant effect. Consistently, isoform-specific antibodies detected only the SPSA1 and SPSC proteins in leaf extracts. Leaf photosynthesis at ambient [CO2] was not different among the genotypes but was 20% lower in spsa1 mutants when measured under saturating [CO2] levels. Carbon partitioning at ambient [CO2] was altered only in the spsa1 null mutant. Cold treatment of plants (4°C for 96h) increased leaf soluble sugars and starch and increased the leaf content of SPSA1 and SPSC proteins twofold to threefold, and of the four null mutants, only spsa1 reduced leaf non-structural carbohydrate accumulation in response to cold treatment. It is concluded that SPSA1 plays a major role in photosynthetic sucrose synthesis in Arabidopsis leaves, and decreases in leaf SPS activity lead to increased starch synthesis and starch turnover and decreased Ribulose 1,5-bisphosphate regeneration-limited photosynthesis but not ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco)-limited photosynthesis, indicating a limitation of triose-phosphate utilization (TPU). Published 2011. This article is a US Government work and is in the public domain in the USA.

Original languageEnglish (US)
Pages (from-to)592-604
Number of pages13
JournalPlant, Cell and Environment
Volume34
Issue number4
DOIs
StatePublished - Apr 2011
Externally publishedYes

Keywords

  • Arabidopsis thaliana
  • Carbon partitioning
  • Cold stress
  • Diurnal growth
  • Gene expression
  • Null mutant
  • Photosynthesis
  • Starch synthesis
  • Sucrose synthesis
  • Sucrose-phosphate synthase (SPS)

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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