PARENT SESSION
Poster Session 36: Genetics / Population Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Adjusting flowering time in the face of changing temperature and precipitation regimes: lessons from the wild winter-annual weed Arabidopsis thaliana.

Israel, Sarah^*,1, Patterson, Angelica¹, Callahan, Hilary¹, ¹ Department of Biological Sciences, New York, NY, 10027

ABSTRACT- Predicting the response of plants to climate change requires assessing their response to both temperatures and precipitation. In the model annual Arabidopsis thaliana, for example, both genes and multiple environmental factors contribute to natural variation in flowering time. Early flowering is constitutive in genotypes lacking a functional allele at the FRIGIDA locus (FRI), whereas extended exposure to cold temperatures (vernalization) is necessary to trigger early flowering in ecotypes possessing a functional FRI allele. In the latter, natural allelic variation at a second, independently segregating locus (FLOWERING LOCUS C, or FLC) can also contribute to the extent of flowering delay in the absence of vernalization. Moreover, physiological responses to drought reportedly vary among ecotypes possessing different allelic combinations at FRI and FLC. We are studying the Bay-0 × Shahdara recombinant inbred (RI) population, which harbors segregating variation at both loci, to test the hypothesis that maladaptive flowering behaviors may be offset by underlying flowering-time genes that pleiotropically improve drought tolerance. We exposed twenty lines to partial (10-d) and full (30-d) vernalization combined factorially with control and mild drought treatments. We documented sources for variation in fruit number, an estimate of fitness; these included main effects of both vernalization and drought, with fitness increased by longer vernalization and, surprisingly, by drought. Genotypic selection gradient analyses indicate that flowering with fewer rosette leaves was favored in all treatments. Both the 30-day vernalization and mild drought tended to attenuate these gradients, even though only the 30-day vernalization treatment contributed to variation in flowering time. We also present regression models that attempt to control for environmentally-induced covariance between flowering time and other traits, such as the size of the seedling and the vegetative rosette.

Key words: genotype-environment interaction, phenotypic plasticity, drought tolerance