JXB Advance Access originally published online on February 17, 2007
Journal of Experimental Botany 2007 58(6):1281-1290; doi:10.1093/jxb/erl283
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
© 2007 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.This paper is available online free of all access charges (see http://jxb.oxfordjournals.org/open_access.html for further details)
RESEARCH PAPER |
Ethylene regulation of fruit softening and cell wall disassembly in Charentais melon
1Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530 Japan
2UMR990 INRA/INP-ENSA Toulouse, Avenue de l'Agrobiopole, BP 32607, F-31326 Castanet-Tolosan, France
3Department of Plant Biology, Cornell University, Ithaca, NY 14853, USA
4Department of Plant Sciences, University of California, Davis, CA 95616, USA
To whom correspondence should be addressed. E-mail: abbennett{at}ucdavis.edu
Cell wall disassembly in ripening fruit is highly complex, involving the dismantling of multiple polysaccharide networks by diverse families of wall-modifying proteins. While it has been reported in several species that multiple members of each such family are expressed in the same fruit tissue, it is not clear whether this reflects functional redundancy, with protein isozymes from a single enzyme class performing similar roles and contributing equally to wall degradation, or whether they have discrete functions, with some isoforms playing a predominant role. Experiments reported here sought to distinguish between cell wall-related processes in ripening melon that were softening-associated and softening-independent. Cell wall polysaccharide depolymerization and the expression of wall metabolism-related genes were examined in transgenic melon (Cucumis melo var. cantalupensis Naud.) fruit with suppressed expression of the 1-aminocyclopropane-1-carboxylate oxidase (ACO) gene and fruits treated with ethylene and 1-methylcyclopropene (1-MCP). Softening was completely inhibited in the transgenic fruit but was restored by treatment with exogenous ethylene. Moreover, post-harvest application of 1-MCP after the onset of ripening completely halted subsequent softening, suggesting that melon fruit softening is ethylene-dependent. Size exclusion chromatography of cell wall polysaccharides, from the transgenic fruits, with or without exogenous ethylene, indicated that the depolymerization of both pectins and xyloglucans was also ethylene dependent. However, northern analyses of a diverse range of cell wall-related genes, including those for polygalacturonases, xyloglucan endotransglucosylase/hydrolases, expansin, and ß-galactosidases, identified specific genes within single families that could be categorized as ethylene-dependent, ethylene-independent, or partially ethylene-dependent. These results support the hypothesis that while individual cell wall-modifying proteins from each family contribute to cell wall disassembly that accompanies fruit softening, other closely related family members are regulated in an ethylene-independent manner and apparently do not directly participate in fruit softening.
Key words: Cell wall modification, enzyme, fruit softening, gene expression, 1-MCP, melon fruit, transgenic plant
* These authors contributed equally to the work presented here.
Received 26 September 2006; Revised 23 November 2006 Accepted 27 November 2006
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  J. W. Johnston, K. Gunaseelan, P. Pidakala, M. Wang, and R. J. Schaffer Co-ordination of early and late ripening events in apples is regulated through differential sensitivities to ethylene J. Exp. Bot., July 1, 2009; 60(9): 2689 - 2699. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y.-X. Zhong, J.-Y. Chen, H.-L. Feng, J.-F. Kuang, R. Xiao, M. Ou, H. Xie, W.-J. Lu, Y.-M. Jiang, and H.-T. Lin Expansin and XET Genes Are Differentially Expressed During Aril Breakdown in Harvested Longan Fruit J. Amer. Soc. Hort. Sci., May 1, 2008; 133(3): 462 - 467. [Abstract] [Full Text] [PDF]
|
|