Plant Growth Regulation

, Volume 45, Issue 3, pp 189–198

The regulation of sweet cherry fruit abscission by polar auxin transport

  • Tijana Blanusa
  • Mark A. Else
  • Christopher J. Atkinson
  • William J. Davies
Article

DOI: 10.1007/s10725-005-3568-9

Cite this article as:
Blanusa, T., Else, M., Atkinson, C. et al. Plant Growth Regul (2005) 45: 189. doi:10.1007/s10725-005-3568-9

Abstract

Inconsistency of cropping is an important problem for UK sweet cherry production. Premature fruit abscission in Prunus can reduce yields severely, however, the environmental cues and hormonal signals that trigger abscission have not been identified. Auxin (IAA) is known to delay abscission by reducing the sensitivity of cells in the abscission zone to ethylene, a promoter of abscission. Therefore, the capacity for polar auxin transport (PAT) through sweet cherry pedicels was examined in relation to fruit abscission. Cherry ‘spurs’ (short shoots) with similar leaf areas and different fruit numbers were phloem-girdled to restrict assimilate movement. Abscission from spurs with many fruit (eight or more) occurred within 14 days of girdling, whereas abscission from spurs with few (two) fruit was minimal. The pedicels’ capacity for PAT in spurs with different fruit numbers was determined 1, 3 and 9 days after girdling (DAG). Fruit were analysed for endogenous IAA concentration 3, 5, 7 and 9 DAG. PAT inhibitors 2,3,5-triiodobenzoic acid or 1-N-naphthylphtalamic acid were applied to pedicels of fruit not expected to abscise, i.e. on spurs with few fruit. The effect of these inhibitors on fruit abscission was determined 14 DAG. The proportion of the transported [3H]-IAA was lower from the outset in pedicels from spurs with many fruit. By 9 DAG, symptoms of fruit abscission were apparent and 40% less [3H] -IAA was transported through pedicels on spurs with many fruit. Fruit endogenous IAA concentrations were similar in the two groups of spurs. Application of PAT inhibitors shortly after girdling increased fruit abscission by 30%. The results suggest that although a decline in PAT is not the only cause of fruit abscission, the maintenance of PAT contributes to fruit retention.

Keywords

Auxin concentration NPA PAT Pedicels Phloem-girdling Prunus Spurs TIBA 

Abbreviations

AZ

abscission zone

BA

benzoic acid

DAFB

days after full bloom

DAG

days after girdling

GC–MS

gas chromatography–mass spectrometry

HPLC

high performance liquid chromatography

IAA

indole-3-acetic acid

LA:FN

leaf area to fruit number ratio

NPA

1-N-naphthylphtalamic acid

PAT

polar auxin transport

TIBA

2,3,5-triiodobenzoic acid

TMS

bis(trimethylsilyl)trifluoroacetamide

Copyright information

© Springer 2005

Authors and Affiliations

  • Tijana Blanusa
    • 1
  • Mark A. Else
    • 1
  • Christopher J. Atkinson
    • 1
  • William J. Davies
    • 2
  1. 1.East Malling ResearchKentUK
  2. 2.Lancaster UniversityLancasterUK
  3. 3.Horticultural Sciences DepartmentRoyal Horticultural SocietySurreyUK

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