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Plant Physiol. 1986 Jun;81(2):584-6. doi: 10.1104/pp.81.2.584.

Diurnal fluctuations in cotton leaf carbon export, carbohydrate content, and sucrose synthesizing enzymes.

Plant physiology

D L Hendrix, S C Huber

Affiliations

  1. United States Department of Agriculture, Agricultural Research Service, Western Cotton Research Laboratory, Phoenix, Arizona 85040.

PMID: 16664860 PMCID: PMC1075380 DOI: 10.1104/pp.81.2.584

Abstract

In fully expanded leaves of greenhouse-grown cotton (Gossypium hirsutum L., cv Coker 100) plants, carbon export, starch accumulation rate, and carbon exchange rate exhibited different behavior during the light period. Starch accumulation rates were relatively constant during the light period, whereas carbon export rate was greater in the afternoon than in the morning even though the carbon exchange rate peaked about noon. Sucrose levels increased throughout the light period and dropped sharply with the onset of darkness; hexose levels were relatively constant except for a slight peak in the early morning. Sucrose synthase, usually thought to be a degradative enzyme, was found in unusually high activities in cotton leaf. Both sucrose synthase and sucrose phosphate synthetase activities were found to fluctuate diurnally in cotton leaves but with different rhythms. Diurnal fluctuations in the rate of sucrose export were generally aligned with sucrose phosphate synthase activity during the light period but not with sucrose synthase activity; neither enzyme activity correlated with carbon export during the dark. Cotton leaf sucrose phosphate synthase activity was sufficient to account for the observed carbon export rates; there is no need to invoke sucrose synthase as a synthetic enzyme in mature cotton leaves. During the dark a significant correlation was found between starch degradation rate and leaf carbon export. These results indicate that carbon partitioning in cotton leaf is somewhat independent of the carbon exchange rate and that leaf carbon export rate may be linked to sucrose formation and content during the light period and to starch breakdown in the dark.

References

  1. Plant Physiol. 1978 Jul;62(1):54-8 - PubMed
  2. Plant Physiol. 1985 Dec;79(4):1127-8 - PubMed
  3. Plant Physiol. 1985 Feb;77(2):275-80 - PubMed
  4. Plant Physiol. 1978 Mar;61(3):380-5 - PubMed
  5. Plant Physiol. 1984 Dec;76(4):910-2 - PubMed
  6. Plant Physiol. 1981 Mar;67(3):489-93 - PubMed
  7. Plant Physiol. 1983 Aug;72(4):1139-41 - PubMed
  8. Plant Physiol. 1979 May;63(5):828-32 - PubMed
  9. Plant Physiol. 1983 Oct;73(2):428-33 - PubMed
  10. Plant Physiol. 1983 Apr;71(4):818-21 - PubMed
  11. Plant Physiol. 1982 Mar;69(3):691-6 - PubMed
  12. Plant Physiol. 1983 Jun;72(2):474-80 - PubMed
  13. Plant Physiol. 1984 Sep;76(1):165-9 - PubMed
  14. Plant Physiol. 1984 Oct;76(2):424-30 - PubMed

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