Poster: Temperature Responses

Abs # 204: Function and regulation of EARLI1 in Arabidopsis thaliana

Presenter:	Bubier, Jason A, jason.bubier@mu.edu
Authors	Bubier, Jason A (A)   Schläppi, Michael R (A)
Affiliations:	(A): Marquette University

An integral component of the flower development pathway is the flowering time gene FLOWERING LOCUS C (FLC). A vernalization treatment 4 degrees C for 30 days eliminates the FLC transcript, allowing the plant to transition to flowering soon after being returned to 22 degrees C. EARLI1 (early Arabidopsis aluminum-induced gene) has been shown to be stably upregulated by vernalization and transiently induced by cold shock. The low temperature stress accompanying vernalization is often characterized by dehydration or osmotic stress. The change in osmotic pressure affects the turgor of the plants which has been shown to induce the biosynthesis of the plant stress hormone abscisic acid (ABA) as well as the increase in cytosolic Ca⁺, triggering cold-induced gene expression and cold acclimation. Further analysis of EARLI1's regulation has shown that it was not induced by ABA but its cold shock induction was Ca⁺ dependent. Protein prediction analysis suggests that EARLI1 is a membrane protein containing a potential motif common to lipid transfer proteins. In support of this, we have preliminary data showing that an EARLI1::GFP fusion protein was localized to the plasma membrane. Recent work demonstrated that the vernalization response of EARLI1 was independent of FLC but varies between accessions. An over-expression of EARLI1 had no effect on flowering time and did not produce a constitutively cold-acclimated plant. T-DNA and RNAi knockouts are currently being analyzed for effects on flowering time as well as on cold acclimation. The regulation of EARLI1 is being reconstituted using promoter::GUS fusions in transgenic plants to determine the minimal gene fragment that allows response to vernalization or cold shock, and to identify the putative response elements.