Temperature-dependent regulation of flowering by antagonistic FLM variants

Abstract

The appropriate timing of flowering is crucial for plant reproductive success. It is therefore not surprising that intricate genetic networks have evolved to perceive and integrate both endogenous and environmental signals, such as carbohydrate and hormonal status, photoperiod and temperature. In contrast to our detailed understanding of the vernalization pathway, little is known about how flowering time is controlled in response to changes in the ambient growth temperature. In Arabidopsis thaliana, the MADS-box transcription factor genes FLOWERING LOCUS M (FLM) and SHORT VEGETATIVE PHASE (SVP) have key roles in this process. FLM is subject to temperature-dependent alternative splicing. Here we report that the two main FLM protein splice variants, FLM-β and FLM-δ, compete for interaction with the floral repressor SVP. The SVP-FLM-β complex is predominately formed at low temperatures and prevents precocious flowering. By contrast, the competing SVP-FLM-δ complex is impaired in DNA binding and acts as a dominant-negative activator of flowering at higher temperatures. Our results show a new mechanism that controls the timing of the floral transition in response to changes in ambient temperature. A better understanding of how temperature controls the molecular mechanisms of flowering will be important to cope with current changes in global climate.

Seasonal Regulation of Petal Number

“…For example, SVP complexes with FLOWERING LOCUS C (FLC) to permit flowering only once FLC levels are sufficiently reduced by progressive chromatin changes in response to prolonged vernalization (Michaels and Amasino, 1999;Bastow et al, 2004;Sung and Amasino, 2004;Li et al, 2008). In addition, repressive complexes of SVP with FLOWERING LOCUS M or MADS AFFECTING FLOWERING2 decline at warmer temperatures, contributing to thermoresponsive flowering (Ratcliffe et al, 2003;Gu et al, 2013;Lee et al, 2013;Posé et al, 2013;Airoldi et al, 2015;Sureshkumar et al, 2016).…”

Scientific report: Training workshop interdisciplinary life sciences

“…We used model 3 to predict the flowering times for various mutations at 16 • C, 23 • C and 27 • C and compared these with available experimental data [Pose13]. Loss of temperature dependence is seen both in experiment and in prediction of the FLM knockout.…”

“…Expression time series (qPCR) of FLM-β and FLM-δ at 23 • C, as well as relative expression of these splice variants after 10 days at 16 • C, 23 • C and 27 • C were obtained from [Pose13]. The equation describing how FLM-β and FLM-δ concentrations change with temperature was approximated by a linear fit between these data points.…”

“…The time of flowering is regulated on a genetic level and is influenced by environmental factors (Figure 1). In Arabidopsis thaliana, one of these environmental factors is temperature [Pose13].…”

Chromatin and epigenetics in all their states: Meeting report of the first conference on Epigenetic and Chromatin Regulation of Plant Traits - January 14 – 15, 2016 - Strasbourg, France

“…23 Previous studies have shown that the MADS-box TF genes FLOWERING LOCUS M (FLM), MADS AFFECTING FLOWERING 2 (MAF2) and SHORT VEGETATIVE PHASE (SVP) play key roles in the temperature-dependent regulation of flowering, with the alternative splicing of FLM and MAF2 working as a molecular thermometer to prevent or induce precocious flowering. 24,25 Alice Pajoro, postdoc in Richard Immink's group (Wageningen University, The Netherlands), reported her work on the epigenetic regulation behind this temperature-mediated alternative splicing process. Using RNA-seq, numerous temperature-mediated alternative splicing events, including many flowering time regulators, were identified.…”