JXB Advance Access originally published online on February 26, 2009
Journal of Experimental Botany 2009 60(4):1375-1386; doi:10.1093/jxb/erp020
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© 2009 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 |
One tissue, two fates: different roles of megagametophyte cells during Scots pine embryogenesis
1Department of Biology, University of Oulu, PO Box 3000, 90014 Oulu, Finland
2Finnish Forest Research Institute, Parkano Research Unit, 39700 Parkano, Finland
3Department of Mathematical Sciences/Statistics, University of Oulu, PO Box 3000, 90014 Oulu, Finland
* To whom correspondence should be addressed: E-mail: jaana.vuosku{at}oulu.fi
In the Scots pine (Pinus sylvestris L.) seed, embryos grow and develop within the corrosion cavity of the megagametophyte, a maternally derived haploid tissue, which houses the majority of the storage reserves of the seed. In the present study, histochemical methods and quantification of the expression levels of the programmed cell death (PCD) and DNA repair processes related genes (MCA, TAT-D, RAD51, KU80, and LIG) were used to investigate the physiological events occurring in the megagametophyte tissue during embryo development. It was found that the megagametophyte was viable from the early phases of embryo development until the early germination of mature seeds. However, the megagametophyte cells in the narrow embryo surrounding region (ESR) were destroyed by cell death with morphologically necrotic features. Their cell wall, plasma membrane, and nuclear envelope broke down with the release of cell debris and nucleic acids into the corrosion cavity. The occurrence of necrotic-like cell death in gymnosperm embryogenesis provides a favourable model for the study of developmental cell death with necrotic-like morphology and suggests that the mechanism underlying necrotic cell death is evolutionary conserved.
Key words: Conifer, developmental cell death, embryogenesis, megagametophyte, necrotic cell death, seed development
Received 12 November 2008; Revised 17 January 2009 Accepted 19 January 2009