© 2008 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 |
Differential regulation of four members of the ACC synthase gene family in plum
1Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre. 4902 Victoria Av. N., PO Box 6000 Vineland Station, ON L0R 2E0, Canada
2University of Guelph, Department of Plant Agriculture, 4890 Victoria Av. N., PO Box 7000 Vineland Station, ON L0R 2E0, Canada
3Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, 1391 Sandford St, London, ON N5V 4T3, Canada
* To whom correspondence should be addressed. E-mail: jsubrama{at}uoguelph.ca
The regulation of ACC synthase (ACS) genes was studied in early (‘Early Golden’) and late (‘Shiro’) Japanese plum cultivars (Prunus salicina L.) in order to determine the role of this gene family in fruit ripening. Of the four Ps-ACS cDNAs isolated, two (Ps-ACS1 and -3) showed differential expression between the two cultivars. Ps-ACS1 accumulated during fruit ripening of ‘Early Golden’ (‘EG’) and ‘Shiro’ (‘SH’) in ethylene-dependent and -independent manners, respectively. Ps-ACS3a transcripts accumulated throughout fruit development and during ‘EG’ fruit ripening. Ps-ACS3b was detected only during ripening of ‘SH’ fruit. Furthermore, Ps-ACS3a transcript accumulation was negatively regulated by ethylene, whereas Ps-ACS3b was positively induced by the hormone. In both cultivars, the expression of Ps-ACS4 and -5 is under positive and negative feedback control by ethylene, respectively. Genetic analyses of ‘EG’ and ‘SH’ cultivars demonstrated that ‘EG’ is homozygous for Ps-ACS3a whereas ‘SH’ is heterozygous for Ps-ACS3 (a/b). The role of ethylene-overproducer 1-like in delaying fruit ripening by interacting with Ps-ACS proteins was also studied. The effect of the plant hormones, auxin, gibberellin, and cytokinin, in regulating ethylene production by promoting the induction of the different Ps-ACS mRNAs in plum was investigated. A model is presented in which differences in Ps-ACS alleles and gene expression between early and late plums are critical in determining the ripening behaviour of the cultivars.
Key words: 1-Aminocyclopropane-1-carboxylic acid synthase (ACS), ACS alleles, auxin, cytokinin, double sigmoid curve growth pattern, ethylene-overproducer 1 (ETO1), gibberellin, plum fruit development and ripening, system 1 and system 2 ethylene production
Received 13 November 2007; Revised 21 January 2008 Accepted 5 February 2008