Temporal and spatial expression of polygalacturonase gene family members reveals divergent regulation during fleshy fruit ripening and abscission in the monocot species oil palm

Roongsattham Peerapat, Morcillo Fabienne, Jantasuriyarat Chatchawan, Pizot Maxime, Moussu Steven, Jayaweera D.M.A., Collin Myriam, Gonzalez-Carranza Zinnia H., Amblard Philippe, Tregear James, Tragoonrung Somvong, Verdeil Jean-Luc, Tranbarger Timothy John. 2012. Temporal and spatial expression of polygalacturonase gene family members reveals divergent regulation during fleshy fruit ripening and abscission in the monocot species oil palm. BMC Plant Biology, 12 (150), 16 p.

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Quartile : Q1, Sujet : PLANT SCIENCES

Abstract : Background: Cell separation that occurs during fleshy fruit abscission and dry fruit dehiscence facilitates seed dispersal, the final stage of plant reproductive development. While our understanding of the evolutionary context of cell separation is limited mainly to the eudicot model systems tomato and Arabidopsis, less is known about the mechanisms underlying fruit abscission in crop species, monocots in particular. The polygalacturonase (PG) multigene family encodes enzymes involved in the depolymerisation of pectin homogalacturonan within the primary cell wall and middle lamella. PG activity is commonly found in the separation layers during organ abscission and dehiscence, however, little is known about how this gene family has diverged since the separation of monocot and eudicots and the consequence of this divergence on the abscission process. Results: The objective of the current study was to identify PGs responsible for the high activity previously observed in the abscission zone (AZ) during fruit shedding of the tropical monocot oil palm, and to analyze PG gene expression during oil palm fruit ripening and abscission. We identified 14 transcripts that encode PGs, all of which are expressed in the base of the oil palm fruit. The accumulation of five PG transcripts increase, four decrease and five do not change during ethylene treatments that induce cell separation. One PG transcript (EgPG4) is the most highly induced in the fruit base, with a 700-5000 fold increase during the ethylene treatment. In situ hybridization experiments indicate that the EgPG4 transcript increases preferentially in the AZ cell layers in the base of the fruit in response to ethylene prior to cell separation. Conclusions: The expression pattern of EgPG4 is consistent with the temporal and spatial requirements for cell separation to occur during oil palm fruit shedding. The sequence diversity of PGs and the complexity of their expression in the oil palm fruit tissues contrast with data from tomato, suggesting functional divergence underlying the ripening and abscission processes has occurred between these two fruit species. Furthermore, phylogenetic analysis of EgPG4 with PGs from other species suggests some conservation, but also diversification has occurred between monocots and eudicots, in particular between dry and fleshy fruit species. (Résumé d'auteur)

Mots-clés Agrovoc : Elaeis guineensis, Abscission, Fruit, Polygalacturonase, Activité enzymatique, Éthylène, Phylogénie, Expression des gènes

Mots-clés géographiques Agrovoc : Thaïlande

Classification Agris : F60 - Plant physiology and biochemistry
F62 - Plant physiology - Growth and development
F30 - Plant genetics and breeding

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

Auteurs et affiliations

  • Roongsattham Peerapat, IRD (FRA)
  • Morcillo Fabienne, CIRAD-BIOS-UMR DIADE (FRA)
  • Jantasuriyarat Chatchawan, Kasetsart University (THA)
  • Pizot Maxime, UM2 (FRA)
  • Moussu Steven
  • Jayaweera D.M.A., University of Nottingham (GBR)
  • Collin Myriam, IRD (FRA)
  • Gonzalez-Carranza Zinnia H., University of Nottingham (GBR)
  • Amblard Philippe, CIRAD-BIOS-UMR AGAP (FRA)
  • Tregear James, IRD (FRA)
  • Tragoonrung Somvong, BIOTEC [National Center for Genetic Engineering and Biotechnology] (THA)
  • Verdeil Jean-Luc, CIRAD-BIOS-UMR AGAP (FRA)
  • Tranbarger Timothy John, IRD (FRA)

Source : Cirad - Agritrop (

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