Early induction of apple fruitlet abscission is characterized by an increase of both isoprene emission and abscisic acid content

Plant Physiol. 2013 Apr;161(4):1952-69. doi: 10.1104/pp.112.208470. Epub 2013 Feb 26.

Abstract

Apple (Malus domestica) fruitlet abscission represents an interesting model system to study the early phases of the shedding process, during which major transcriptomic changes and metabolic rearrangements occur within the fruit. In apple, the drop of fruits at different positions within the cluster can be selectively magnified through chemical thinners, such as benzyladenine and metamitron, acting as abscission enhancers. In this study, different abscission potentials were obtained within the apple fruitlet population by means of the above-cited thinners. A metabolomic study was conducted on the volatile organic compounds emitted by abscising fruitlets, allowing for identification of isoprene as an early marker of abscission induction. A strong correlation was also observed between isoprene production and abscisic acid (ABA) levels in the fruit cortex, which were shown to increase in abscising fruitlets with respect to nonabscising ones. Transcriptomic evidence indicated that abscission-related ABA is biologically active, and its increased biosynthesis is associated with the induction of a specific ABA-responsive 9-cis-epoxycarotenoid dioxygenase gene. According to a hypothetical model, ABA may transiently cooperate with other hormones and secondary messengers in the generation of an intrafruit signal leading to the downstream activation of the abscission zone. The shedding process therefore appears to be triggered by multiple interdependent pathways, whose fine regulation, exerted within a very short temporal window by both endogenous and exogenous factors, determines the final destiny of the fruitlets.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / metabolism*
  • Abscisic Acid / pharmacology
  • Biosynthetic Pathways / drug effects
  • Biosynthetic Pathways / genetics
  • Butadienes / analysis*
  • Fruit / drug effects
  • Fruit / growth & development*
  • Fruit / metabolism*
  • Gene Expression Profiling
  • Gene Expression Regulation, Plant / drug effects
  • Hemiterpenes / analysis*
  • Malus / drug effects
  • Malus / genetics
  • Malus / growth & development*
  • Malus / metabolism
  • Models, Biological
  • Molecular Sequence Data
  • Pentanes / analysis*
  • Volatile Organic Compounds / analysis

Substances

  • Butadienes
  • Hemiterpenes
  • Pentanes
  • Volatile Organic Compounds
  • isoprene
  • Abscisic Acid

Associated data

  • GENBANK/ACL13550
  • GENBANK/DQ438989