Vernalization: Winter and the Timing of Flowering in Plants

Abstract

Plants have evolved many systems to sense their environment and to modify their growth and development accordingly. One example is vernalization, the process by which flowering is promoted as plants sense exposure to the cold temperatures of winter. A requirement for vernalization is an adaptive trait that helps prevent flowering before winter and permits flowering in the favorable conditions of spring. In Arabidopsis and cereals, vernalization results in the suppression of genes that repress flowering. We describe recent progress in understanding the molecular basis of this suppression. In Arabidopsis, vernalization involves the recruitment of chromatin-modifying complexes to a clade of flowering repressors that are silenced epigenetically via histone modifications. We also discuss the similarities and differences in vernalization between Arabidopsis and cereals.

NO FLOWERING IN SHORT DAY (NFL) is a bHLH transcription factor that promotes flowering specifically under short-day in Arabidopsis

“…Some autonomous pathway mutants also fail to flower under SD. However, they flower very late under LD as well (Kim et al, 2009). Unlike known late-flowering mutants, nfl mutants failed to flower only under SD conditions, but not under LD conditions (Figs 2 and 3).…”

“…These four genetic pathways regulate the expression of floral integrator genes, such as FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) that activate the downstream floral identity genes [e.g. APETALA1 (AP1) and LEAFY (LFY)] to promote flowering (Andrés and Coupland, 2012;Kim et al, 2009;Song et al, 2015).…”

“…The vernalization pathway controls flowering time through the floral repressors FLC and other FLC clade members (Kim et al, 2009). The FLC clade consists of MADS-box transcription factors FLOWERING LOCUS M/MADS AFFECTING FACTOR 1 (MAF1) and MAF2-MAF5 (Kim and Sung, 2010).…”

“…In non-vernalized plants, FLC represses expression of FT and SOC1 in phloem and in the meristem and FD in the meristem (Searle et al, 2006). After vernalization, FLC expression is strongly repressed through histone modifications (Kim et al, 2009). Repression of FLC leads to activation of downstream floral integrators, FT and SOC1 that allow plants to flower after a long duration of cold exposure.…”

Phosphate starvation induces DNA methylation in the vicinity of cis-acting elements known to regulate the expression of phosphate–responsive genes

“…7,8 Therefore, epigenetic states are dynamic and can be effectively remodeled by environmental cues, developmental signals, and disease states to enhance genome transcriptional plasticity. 7,[9][10][11] Phosphorus (P) is an important macronutrient for all living organisms that is a critical component of nucleic acids and membrane phospholipids, as well as an essential element for energy-dependent metabolic processes. 12 Plants absorb P as inorganic phosphate (Pi), a chemical form of P with low availability and mobility in most soils.…”