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Cold stress triggers abscission through ABA-dependent signal transduction in early developing apple
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  • Youngsuk Lee,
  • Giap Do Van,
  • Seonae Kim,
  • Hunjoong Kweon,
  • Tony McGhie
Youngsuk Lee
Rural Development Administration
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Giap Do Van
Rural Development Administration
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Seonae Kim
Rural Development Administration
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Hunjoong Kweon
Rural Development Administration
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Tony McGhie
New Zealand Institute for Plant and Food Research Ltd
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Abstract

Fruit abscission is a complex physiological process that is regulated by internal and environmental factors. During early development, apple fruit are exposed to extreme temperature fluctuations that are associated with premature fruit drop; however, its effect on fruit abscission is largely unknown. We hypothesized that fruit abscission is triggered by cold stress and investigated the molecular basis of premature fruit drop using RNA-seq and metabolomics data from apple fruit undergoing abscission following cold stress in the field. Genes responsive to abscisic acid signalling and cell wall degradation were up-regulated during abscission, consistent with the increased abscisic acid concentrations detected by LCMS. We performed ex-vivo cold shock experiments with excised tree subunits consisting of a branch, pedicel, and fruit. Abscission induction occurred in the cold-stressed subunits with concurrent up-regulation of abscisic acid biosynthesis (MdNCED1) and metabolism (MdCYP707A) genes, and ethylene biosynthesis (MdACS1) and receptor (MdETR2) genes in pedicel. Another key finding was the activation of cytoplasmic streaming of abscission-zone cells detected by electron microscopy. Our results provide a novel insight into the molecular basis of fruit abscission physiology in response to cold stress in apple.

Peer review status:UNDER REVIEW

14 Sep 2020Submitted to Plant, Cell & Environment
15 Sep 2020Assigned to Editor
15 Sep 2020Submission Checks Completed
20 Sep 2020Reviewer(s) Assigned