The circadian clock regulates receptor-mediated immune responses to an herbivore-associated molecular pattern.

Plants activate induced defenses through the recognition of molecular patterns. Like pathogen-associated molecular patterns (PAMPs), herbivore-associated molecular patterns (HAMPs) can be recognized by cell surface pattern recognition receptors leading to defensive transcriptional changes in host plants. Herbivore-induced defensive outputs are regulated by the circadian clock, but the underlying molecular mechanisms remain unknown.

A florigen-expressing subpopulation of companion cells expresses other small proteins and reveals a nitrogen-sensitive repressor.

The precise onset of flowering is crucial to ensure successful plant reproduction. The gene () encodes florigen, a mobile signal produced in leaves that initiates flowering at the shoot apical meristem. In response to seasonal changes, is induced in phloem companion cells located in distal leaf regions.

Florigen-producing cells express FPF1-LIKE PROTEIN 1 that accelerates flowering and stem growth in long days with sunlight red/far-red ratio in .

Seasonal changes in spring induce flowering by expressing the florigen, FLOWERING LOCUS T (FT), in . is expressed in unique phloem companion cells with unknown characteristics. The question of which genes are co-expressed with and whether they have roles in flowering remains elusive.

Disrupting FKF1 homodimerization increases FT transcript levels in the evening by enhancing CO stabilization.

FKF1 dimerization is crucial for proper FT levels to fine-tune flowering time. Attenuating FKF1 homodimerization increased CO abundance by enhancing its COP1 binding, thereby accelerating flowering under long days. In Arabidopsis (Arabidopsis thaliana), the blue-light photoreceptor FKF1 (FLAVIN-BINDING, KELCH REPEAT, F-BOX 1) plays a key role in inducing the expression of FLOWERING LOCUS T (FT), encoding the main florigenic signal in plants, in the late afternoon under long-day conditions (LDs) by forming dimers with FT regulators.

Responsiveness to long days for flowering is reduced in Arabidopsis by yearly variation in growing season temperatures.

Conservative flowering behaviours, such as flowering during long days in summer or late flowering at a high leaf number, are often proposed to protect against variable winter and spring temperatures which lead to frost damage if premature flowering occurs. Yet, due the many factors in natural environments relative to the number of individuals compared, assessing which climate characteristics drive these flowering traits has been difficult. We applied a multidisciplinary approach to 10 winter-annual Arabidopsis thaliana populations from a wide climactic gradient in Norway.

The FLOWERING LOCUS T gene expression is controlled by high-irradiance response and external coincidence mechanism in long days in Arabidopsis.

In natural long days, the florigen gene FLOWERING LOCUS T (FT) shows a bimodal expression pattern with morning and dusk peaks in Arabidopsis. This pattern differs from the one observed in the laboratory, and little is known about underlying mechanisms. A red : far-red (R : FR) ratio difference between sunlight and fluorescent light causes this FT pattern mismatch.

Photoperiodic flowering in Arabidopsis: Multilayered regulatory mechanisms of CONSTANS and the florigen FLOWERING LOCUS T.

The timing of flowering affects the success of sexual reproduction. This developmental event also determines crop yield, biomass, and longevity. Therefore, this mechanism has been targeted for improvement along with crop domestication.

Clock-Controlled and Cold-Induced Alters Growth and Development in Arabidopsis.

The circadian clock represents a critical regulatory network, which allows plants to anticipate environmental changes as inputs and promote plant survival by regulating various physiological outputs. Here, we examine the function of the clock-regulated transcription factor, CYCLING DOF FACTOR 6 (CDF6), during cold stress in . We found that the clock gates transcript accumulation in the vasculature during cold stress.

BrABF3 promotes flowering through the direct activation of CONSTANS transcription in pak choi.

Drought stress triggers the accumulation of the phytohormone abscisic acid (ABA), which in turn activates the expression of the floral integrator gene CONSTANS (CO), accelerating flowering. However, the molecular mechanism of ABA-induced CO activation remains elusive. Here, we conducted a yeast one-hybrid assay using the CO promoter from Brassica campestris (syn.

Flowering Times of Wild Accessions From Across Norway Correlate With Expression Levels of , , and Genes.

Temperate species often require or flower most rapidly in the long daylengths, or photoperiods, experienced in summer or after prolonged periods of cold temperatures, referred to as vernalization. Yet, even within species, plants vary in the degree of responsiveness to these cues. In , () and () genes are key to photoperiod and vernalization perception and antagonistically regulate () to influence the flowering time of the plants.

Simple Nuclei Preparation and Co-immunoprecipitation Procedures for Studying Protein Abundance and Interactions in Plant Circadian Time Courses.

The plant circadian clock regulates multiple developmental and physiological events that occur at specific times and seasons. As many of the currently known clock proteins and clock-associated regulators are transcription factors, analyzing molecular events in the nuclei is crucial. In addition, long-time course analyses of protein abundance and interactions are often required to assess the role of the circadian clock on clock-regulated phenomena.

Steric and Electronic Interactions at Gln154 in ZEITLUPE Induce Reorganization of the LOV Domain Dimer Interface.

Plants measure light quality, intensity, and duration to coordinate growth and development with daily and seasonal changes in environmental conditions; however, the molecular details linking photochemistry to signal transduction remain incomplete. Two closely related light, oxygen, or voltage (LOV) domain-containing photoreceptor proteins, ZEITLUPE (ZTL) and FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1), divergently regulate the protein stability of circadian clock and photoperiodic flowering components to mediate daily and seasonal development. Using structural approaches, we identified that mutations at the Gly46 position led to global rearrangements of the ZTL dimer interface in the isolated ZTL-LOV domain.

Building customizable auto-luminescent luciferase-based reporters in plants.

Bioluminescence is a powerful biological signal that scientists have repurposed as a reporter for gene expression in plants and animals. However, there are downsides associated with the need to provide a substrate to these reporters, including its high cost and non-uniform tissue penetration. In this work we reconstitute a fungal bioluminescence pathway (FBP) using a composable toolbox of parts.

GIGANTEA Regulates the Timing Stabilization of CONSTANS by Altering the Interaction between FKF1 and ZEITLUPE.

Plants monitor changes in day length to coordinate their flowering time with appropriate seasons. In Arabidopsis , the diel and seasonal regulation of CONSTANS (CO) protein stability is crucial for the induction of () gene in long days. FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1) and ZEITLUPE (ZTL) proteins control the shape of CO expression profile antagonistically, although regulation mechanisms remain unknown.

An explanatory model of temperature influence on flowering through whole-plant accumulation of in .

We assessed mechanistic temperature influence on flowering by incorporating temperature-responsive flowering mechanisms across developmental age into an existing model. Temperature influences the leaf production rate as well as expression of (), a photoperiodic flowering regulator that is expressed in leaves. The Framework Model incorporated temperature influence on leaf growth but ignored the consequences of leaf growth on and direct temperature influence of expression.

Time-resolved interaction proteomics of the GIGANTEA protein under diurnal cycles in Arabidopsis.

The plant-specific protein GIGANTEA (GI) controls many developmental and physiological processes, mediating rhythmic post-translational regulation. GI physically binds several proteins implicated in the circadian clock, photoperiodic flowering, and abiotic stress responses. To understand GI's multifaceted function, we aimed to comprehensively and quantitatively identify potential interactors of GI in a time-specific manner, using proteomics on Arabidopsis plants expressing epitope-tagged GI.

Dawn and photoperiod sensing by phytochrome A.

In plants, light receptors play a pivotal role in photoperiod sensing, enabling them to track seasonal progression. Photoperiod sensing arises from an interaction between the plant's endogenous circadian oscillator and external light cues. Here, we characterize the role of phytochrome A (phyA) in photoperiod sensing.

Molecular basis of flowering under natural long-day conditions in Arabidopsis.

Plants sense light and temperature changes to regulate flowering time. Here, we show that expression of the Arabidopsis florigen gene, FLOWERING LOCUS T (FT), peaks in the morning during spring, a different pattern than we observe in the laboratory. Providing our laboratory growth conditions with a red/far-red light ratio similar to open-field conditions and daily temperature oscillation is sufficient to mimic the FT expression and flowering time in natural long days.