SHORT VEGETATIVE PHASE Up-Regulates TEMPRANILLO2 Floral Repressor at Low Ambient Temperatures

Abstract

Plants integrate day length and ambient temperature to determine the optimal timing for developmental transitions. In Arabidopsis (Arabidopsis thaliana), the floral integrator FLOWERING LOCUS T (FT) and its closest homolog TWIN SISTER OF FT promote flowering in response to their activator CONSTANS under long-day inductive conditions. Low ambient temperature (16°C) delays flowering, even under inductive photoperiods, through repression of FT, revealing the importance of floral repressors acting at low temperatures. Previously, we have reported that the floral repressors TEMPRANILLO (TEM; TEM1 and TEM2) control flowering time through direct regulation of FT at 22°C. Here, we show that tem mutants are less sensitive than the wild type to changes in ambient growth temperature, indicating that TEM genes may play a role in floral repression at 16°C. Moreover, we have found that TEM2 directly represses the expression of FT and TWIN SISTER OF FT at 16°C. In addition, the floral repressor SHORT VEGETATIVE PHASE (SVP) directly regulates TEM2 but not TEM1 expression at 16°C. Flowering time analyses of svp tem mutants indicate that TEM may act in the same genetic pathway as SVP to repress flowering at 22°C but that SVP and TEM are partially independent at 16°C. Thus, TEM2 partially mediates the temperature-dependent function of SVP at low temperatures. Taken together, our results indicate that TEM genes are also able to repress flowering at low ambient temperatures under inductive long-day conditions. Plants constantly monitor environmental and endogenous signals to control their growth and adjust developmental responses to daily and seasonal cues (Penfield, 2008). During the juvenile phase, plants are not competent to flower; they are insensitive to inductive environmental factors, such as favorable conditions of day length or temperature. The transition to the adult phase permits reaching the competence to respond to those signals, which is essential to trigger flowering during the reproductive phase (Bergonzi and Albani, 2011;Huijser and Schmid, 2011). Consequently, the control of flowering time is a key determinant of reproductive success and plays an essential role in plant adaptation to seasons and geography.Flowering time is controlled by an intricate network of interdependent genetic pathways that monitor and respond to both endogenous and environmental signals. These pathways include age, photoperiod and light quality, GA, thermosensory (ambient temperature), vernalization, and autonomous pathways (Fornara et al., 2010;Srikanth and Schmid, 2011). In Arabidopsis (Arabidopsis thaliana), it is well documented the noteworthy regulation of the timing of flowering by day length or photoperiod and temperature (for review, see Andrés and Coupland, 2012;Song et al., 2013;Chew et al., 2014;Romera-Branchat * Address correspondence to soraya.pelaz@cragenomica.es. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions f...

TEMPRANILLO is a direct repressor of the microRNA miR172

“…Together with the binding of TEMs to MIR172C chromatin, the effect of TEMs on MIR172A , MIR172B and MIR172C RNAs and mature miR172 levels (Figure ) indicates that TEMs regulate flowering partly through miR172, by repressing the expression of MIR172A , MIR172B and directly that of MIR172C . Taking into account previous reports, we can conclude that the regulation of flowering time by TEMs is mainly mediated by FT, TSF and GA (Castillejo and Pelaz, ; Osnato et al ., ; Marín‐González et al ., ), but also partially by miR172.…”

“…It has been described that TEM1 and TEM2 are transcriptional repressors that directly downregulate FT , TSF , GA3ox1 and GA3ox2 (Castillejo and Pelaz, ; Osnato et al ., ; Marín‐González et al ., ). We show here that TEMs downregulate miR172 levels through direct binding to at least one MIR172 gene, MIR172C , and transcriptional repression of MIR172A , MIR172B and MIR172C (Figure ).…”

“…The different genetic pathways acting in the flowering time network share several genes (Bouché et al ., ). By revealing the role of TEMs in the age‐dependent flowering pathway, our work suggests that TEMs link this pathway to the photoperiod, GA and ambient temperature pathways, in which TEMs are also involved (Castillejo and Pelaz, ; Osnato et al ., ; Marín‐González et al ., ), pointing to additional inter‐communication of genetic pathways within the flowering network.…”

TEMPRANILLO Reveals the Mesophyll as Crucial for Epidermal Trichome Formation

“…information from diverse redundant pathways (Yant et al, 2010;Tao et al, 2012;Marín-González et al, 2015). Similarly to other transcription factor families, it has been suggested that RAV genes may control additional biological aspects during plant development (Matías-Hernández et al, 2014).…”

Manipulation of flowering time and branching by overexpression of the tomato transcription factor SlZFP2

“…For example, FT transcription is directly activated by CONSTANS (CO), CRYPTOCHROME-INTERACTING BASIC-HELIX-LOOP-HELIX1 (CIB1), WRKY71, PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) and Morf-related Gene 2 (MRG2) (Kumar et al, 2012;Liu et al, 2008Liu et al, , 2013Tiwari et al, 2010;Xu et al, 2014;Yu et al, 2016). In addition, FT transcription is also directly repressed by TEMPRANILLO (TEM) 1 and 2, TARGET OF EAT (TOE) 1 and 2, SHORT VEGETATIVE PHASE (SVP), CYCLING DOF FACTOR1 (CDF1), EARLY-FLOWERING MYB PROTEIN (EFM), SCHLAFMUTZE (SMZ) and SCHNARCHZAPFEN (SNZ) (Marin-Gonzalez et al, 2015;Mathieu et al, 2009;Song et al, 2012;Yan et al, 2014;Zhang et al, 2015). Thus, transcriptional regulation of FT expression plays a crucial role in flowering time control in Arabidopsis.…”