PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of bmcpsBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Plant Biology
 
BMC Plant Biol. 2012; 12: 15.
Published online Jan 27, 2012. doi:  10.1186/1471-2229-12-15
PMCID: PMC3296646
The role of the Arabidopsis FUSCA3 transcription factor during inhibition of seed germination at high temperature
Rex S Chiu,1,2 Hardeep Nahal,2,3 Nicholas J Provart,2,3 and Sonia Gazzarrinicorresponding author1,2
1Department of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, ON, M1C 1A4 Canada
2Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5 Canada
3Centre for the Analysis of Genome Evolution and Function (CAGEF), University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5 Canada
corresponding authorCorresponding author.
Rex S Chiu: chiu/at/utoronto.ca; Hardeep Nahal: hardeep.nahal/at/utoronto.ca; Nicholas J Provart: nicholas.provart/at/utoronto.ca; Sonia Gazzarrini: gazzarrini/at/utsc.utoronto.ca
Received September 19, 2011; Accepted January 27, 2012.
Abstract
Background
Imbibed seeds integrate environmental and endogenous signals to break dormancy and initiate growth under optimal conditions. Seed maturation plays an important role in determining the survival of germinating seeds, for example one of the roles of dormancy is to stagger germination to prevent mass growth under suboptimal conditions. The B3-domain transcription factor FUSCA3 (FUS3) is a master regulator of seed development and an important node in hormonal interaction networks in Arabidopsis thaliana. Its function has been mainly characterized during embryonic development, where FUS3 is highly expressed to promote seed maturation and dormancy by regulating ABA/GA levels.
Results
In this study, we present evidence for a role of FUS3 in delaying seed germination at supraoptimal temperatures that would be lethal for the developing seedlings. During seed imbibition at supraoptimal temperature, the FUS3 promoter is reactivated and induces de novo synthesis of FUS3 mRNA, followed by FUS3 protein accumulation. Genetic analysis shows that FUS3 contributes to the delay of seed germination at high temperature. Unlike WT, seeds overexpressing FUS3 (ML1:FUS3-GFP) during imbibition are hypersensitive to high temperature and do not germinate, however, they can fully germinate after recovery at control temperature reaching 90% seedling survival. ML1:FUS3-GFP hypersensitivity to high temperature can be partly recovered in the presence of fluridone, an inhibitor of ABA biosynthesis, suggesting this hypersensitivity is due in part to higher ABA level in this mutant. Transcriptomic analysis shows that WT seeds imbibed at supraoptimal temperature activate seed-specific genes and ABA biosynthetic and signaling genes, while inhibiting genes that promote germination and growth, such as GA biosynthetic and signaling genes.
Conclusion
In this study, we have uncovered a novel function for the master regulator of seed maturation, FUS3, in delaying germination at supraoptimal temperature. Physiologically, this is important since delaying germination has a protective role at high temperature. Transcriptomic analysis of seeds imbibed at supraoptimal temperature reveal that a complex program is in place, which involves not only the regulation of heat and dehydration response genes to adjust cellular functions, but also the activation of seed-specific programs and the inhibition of germination-promoting programs to delay germination.
Keywords: High temperature, FUSCA3, Seed germination, Hormones, ABA, Transcriptome
Articles from BMC Plant Biology are provided here courtesy of
BioMed Central