Abstract Detail

Ecological Section

Litt, Amy [1], Nowogrodzki, Anna [1], Lalchan, Rebecca [2], Franks, Steven [2].

The role of Brassica rapa FLC orthologs in flowering time divergence due to drought in natural populations in California.

Studies have shown that two natural populations of field mustard (Brassica rapa) underwent a significant heritable shift to earlier flowering in response to five years of drought in Southern California. Although both populations flower over a period of weeks, the average time to first flowering shifted earlier by as much as 8 days; this is consistent with theory that suggests earlier flowering time is advantageous during drought conditions. To identify the molecular basis of this observed evolutionary shift in flowering time we are using a candidate gene approach, focusing on the four paralogs of Arabidopsis FLC present in the B. rapa genome. FLC has been shown to negatively regulate flowering time in Arabidopsis and Brassica in a dosage-dependent fashion. We hypothesize that the presence of four functionally similar paralogs allows fine tuning of flowering time: dry conditions favor alleles that produce early flowering, whereas in wetter conditions alleles that promote later flowering would be favored. To test this hypothesis we are sequencing the coding region of the four loci as well as putative regulatory regions. Preliminary data suggest that the 5’ end of the genes does not show significant variation, consistent with the presence of the highly conserved MADS DNA-binding domain in that portion. Current work is focusing on the potentially more variable 3’ end, promoter region and first intron to determine if allelic variation is correlated with flowering time. We are also using quantitative gene expression analyses to test the hypothesis that changes in the activity of these genes are correlated with the evolutionary shift in flowering time. Preliminary data suggest that members of the earlier flowering population do have lower levels of transcript of the four genes than the later flowering population. In addition we are investigating whether differences in alleles and/or in the expression of the four loci can explain the range of flowering times observed within each population.

Broader Impacts:

1 - The New York Botanical Garden, 200th St and Southern Boulevard, Bronx, NY, 10458-5126, USA
2 - Fordham University, Department of Biological Sciences, Larkin Hall, 441 East Fordham Rd, Bronx, NY, 10458, USA

Keywords:
Brassica
FLC
flowering time
climate change response.

Presentation Type: Oral Paper:Papers for Sections
Session: 43
Location: 552B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 2:15 PM
Number: 43004
Abstract ID:429