eprintid: 197
rev_number: 4
eprint_status: archive
userid: 6
dir: disk0/00/00/01/97
datestamp: 2009-01-08
lastmod: 2015-05-29 19:49:12
status_changed: 2009-04-08 16:55:47
type: report
metadata_visibility: show
item_issues_count: 0
creators_name: Penfield, Steven
creators_name: Fozard, John
contributors_name: Bastow, Ruth
contributors_name: King, John
contributors_name: Savage, Natasha
title: Network properties underlying seed germination control
ispublished: pub
subjects: other
studygroups: mpssg1
full_text_status: public
abstract: We sought to gain a mechanistic understanding of the control of seed dormancy and germination by hormone balance. The field has matured to a stage where most of the key genes are known, and competing hypotheses have been proposed to explain how hormone balance works in seeds. During the meeting we simplified a more complex model of seed germination (Figure 1), reducing it to a tractable network. We then showed that if considered as a set of competing protein complexes the network took on the properties of a switch. Results from two models of the reduced network, which incorporated the biological switching phenomena, were found to be in good agreement with both wild and mutant phenotypic data. Our models made the novel prediction that one complex in particular was key to promoting germination, and this prediction can now
be tested in the laboratory.
problem_statement: Seed germination control requires the assimilation of signalling from multiple input pathways. Environmental signals such as light control the level of the hormones gibberellin (GA) and abscisic acid (ABA) in seeds. Since the 1960s is has been hypothesised that the 'balance' of the germination-promoting hormone GA and the germination inhibiting hormone ABA controls the decision to germinate. However, to date, despite massive advances in the understanding of the molecular basis of germination control, it is still unclear exactly how hormone balance works.

The decision to germinate (or not) is essentially a binary output of a complex molecular network. This germination-controlling network comprises a set of complex interlocking feedback loops involving regulation at the mRNA and protein levels, through which the abundance of GA and ABA is managed. Furthermore, the output of the network is transduced through a transcription factor complex that is also integral to the function of the feedback loops themselves. The same complex also performs a key step in environmental signal transduction.

The primary goal will be to create a platform for modelling the effect of one key input, light, and to ask which, if any, of the current conceptual models of germination control can account for observed behaviour. In the future model solutions will be integrated with traditional hydrothermal time models linking molecular events to seed germination studies under field conditions.
date: 2007-12
date_type: published
pages: 8
citation:   Penfield, Steven and Fozard, John  (2007) Network properties underlying seed germination control.  [Study Group Report]     
document_url: http://miis.maths.ox.ac.uk/miis/197/1/report1.pdf