CONSTANS, a HUB for all seasons: How photoperiod pervades plant physiology regulatory circuits

Transcriptome Analysis Reveals Co-Expression Regulation of Sugar Transport and Signaling Networks in Initiating Stolon-to-Tuber Transition in Potato

The network regulatory mechanism governing the dynamics of plant maturity and tuber development in potatoes (Solanum tuberosum L.) has remained a major focus in potato molecular biology research. In this study, three potato cultivars with different maturity periods ('Shishu 2', 'Zhongshu 3', and 'Zhongshu 49') were examined. RNA sequencing was performed on samples from five tissues, including the leaves, stems, stolon (T0), sub-apical swellings (T1), and initiation stage (T2), to reveal the co-expression regulatory network involved in leaf, stem, and tuber development. StSWEET11 and StSP6A were significantly upregulated in the early-maturing cultivar 'Shishu 2'. Differentially expressed genes were classified into 18 modules (ME) using weighted gene co-expression network analysis (WGCNA). Among these, ME1, ME3, and ME13 showed significant positive correlations with leaf tissue, ME2, ME4, and ME15 with stem tissue, and ME7, ME8, and ME14 with T1 and T2 tissues. StSP5G was identified as the core hub gene of ME4. Genes such as StCOL1, StSWEET11, and StSP6A exhibited significant co-expression in leaf-related modules. StGIGANTEA and StGIGANTEA-like played important regulatory roles in linking the expression networks of stems and tubers. Metabolism-related genes, including StSUSⅠc/StSuSy4 and StDPE1, were also found to be crucial in mediating interactions between leaf and tuber tissues. Therefore, this study provides new insights into the regulatory network governing tuberous signal transmission from leaves and stems to tubers.

Complex Signaling Networks Underlying Blue-Light-Mediated Floral Transition in Plants

Blue light (BL) is important in regulating floral transition. In a controlled environment production system, BL can be manipulated easily and precisely in aspects like peak wavelength, intensity, duration, and co-action with other wavelengths. However, the results of previous studies about BL-mediated floral transition are inconsistent, which implies that an in-depth critical examination of the relevant physiological mechanisms is necessary. This review consolidates the recent findings on the role of BL in mediating floral transition not only in model plants, such as Arabidopsis thaliana, but also in crops, especially horticultural crops. The photoreceptors, floral integrator proteins, signal pathways, and key network components involved in BL-mediated floral transition are critically reviewed. This review provides possible explanations for the contrasting results of previous studies on BL-mediated flowering; it provides valuable information to explain and develop BL manipulation strategies for mediating flowering, especially in horticultural plants. The review also identifies the knowledge gaps and outlines future directions for research in related fields.

TANDEM ZINC-FINGER/PLUS3 integrates light signaling and flowering regulatory pathways at the chromatin level

Environmental and endogenous stimuli determine plant developmental transitions including flowering through multiple signaling cascades. Although the key activators and repressors of flowering initiation are defined, the components and mechanisms integrating light signaling and flowering pathways are not fully established. This study investigates the role of TANDEM ZINC-FINGER/PLUS3 (TZP), a light-integrating transcriptional regulator, to elucidate how light cues influence the epigenetic regulation of flowering in Arabidopsis thaliana. To dissect the molecular function of TZP, this study employed a combination of genetics, RNA sequencing, chromatin immunoprecipitation sequencing and phenotypic assays. These approaches were used to determine TZP's genomic binding sites, its downstream gene targets and its influence on flowering time and chromatin modifications. TANDEM ZINC-FINGER/PLUS3 was found to directly associate with the promoter regions of chromatin-modifying genes, including FLOWERING LOCUS D (a histone H3K4 demethylase) and histone deacetylase 6 (a histone deacetylase). This regulation promotes a chromatin environment that represses FLOWERING LOCUS C (FLC) transcription, thereby accelerating flowering. TANDEM ZINC-FINGER/PLUS3 thus functions upstream of multiple pathways integrating photoperiodic and autonomous floral cues. TANDEM ZINC-FINGER/PLUS3 mediates crosstalk between light signaling and flowering pathways by modulating chromatin structure at the FLC locus. This provides a mechanistic framework for understanding how environmental signals dynamically influence epigenetic regulation of developmental transitions.

Tomato CONSTANS-Like1 promotes anthocyanin biosynthesis under short day and suboptimal low temperature

Plant growth and development are precisely controlled by light and temperature during their life span. However, the mechanism by which photoperiod and seasonal changes influence the physiological response of day-neutral plants, such as tomato (Solanum lycopersicum), remains unclear. Here, we found that the tomato CONSTANS (CO) close homolog, CONSTANS-Like1 (SlCOL1), does not affect the flowering of tomato under either long-day or short-day conditions. However, CRISPR/Cas9-mediated editing of SlCOL1 showed a much lower anthocyanin accumulation in mutant than in wild-type plants, especially under SD at suboptimal low-temperature conditions. SlCOL1 directly activated the Hoffman's Anthocyanin 1 (SlAN1) promoter and interacted with SlAN1 to promote anthocyanin biosynthesis under SD. The cold-induced upregulation of SlCOL1 further promoted anthocyanin accumulation and enhanced reactive oxygen species scavenging under SD at low-temperature conditions. These results reveal that the SlCOL1-SlAN1 module collaboratively regulates anthocyanin accumulation under SD and cold conditions, which could help tomato counteract the cold autumn/winter season in nature.

Comparative transcriptome analysis of emerging young and mature leaves of Bienertia sinuspersici, a single-cell C4 plant

Background

Efficient carbon capture by plants is crucial to meet the increasing demands for food, fiber, feed, and fuel worldwide. One potential strategy to improve the photosynthetic performance of plants is the conversion of C3-type crops to C4-type crops, enabling them to perform photosynthesis at higher temperatures and with less water. C4-type crops, such as corn, possess a distinct Kranz anatomy, where photosynthesis occurs in two distinct cell types. Remarkably, Bienertia sinuspersici is one of the four known land plant species that perform C4 photosynthesis within a single cell. This unique single-cell C4 (SCC4) anatomy is characterized by dimorphic chloroplasts and corresponding intracellular biochemistry. Because young, emergent Bienertia leaves first exhibit C3anatomy and then differentiate into the C4 anatomy as the leaves mature, Bienertia represents an excellent system to explore the basis for a C3 to C4 transition.

Methods

To gain insight into the genes and pathways associated with the C3 to C4 transition between emerging young and mature Bienertia sinuspersici leaves, a comparative transcriptome analysis was conducted in which global gene expression and gene ontologies were compared between the two stages.

Results

In the emergent leaf, differentially expressed genes and enrichment of ontologies associated with the cell cycle and cytoskeletal dynamics were observed, while the mature leaf displayed enrichment of processes associated with photosynthesis and cellular energetics. Additionally, numerous transcription factors (TFs) associated with metabolic homeostasis, hormone and stress signaling, and developmental regulation were expressed throughout development, with unique TF expression profiles at each stage. These data expand our insights into the molecular basis of Binertia's unique cellular compartmentalization, chloroplast dimorphism, and single-cell C4 biochemistry and provide information that will be useful in the ongoing efforts to transform C3-type crops into C4 type.

Phase separation as a key mechanism in plant development, environmental adaptation, and abiotic stress response

Liquid-liquid phase separation is a fundamental biophysical process in which biopolymers, such as proteins, nucleic acids, and their complexes, spontaneously demix into distinct coexisting phases. This phenomenon drives the formation of membraneless organelles-cellular subcompartments without a lipid bilayer that perform specialized functions. In plants, phase-separated biomolecular condensates play pivotal roles in regulating gene expression, from genome organization to transcriptional and post-transcriptional processes. In addition, phase separation governs plant-specific traits, such as flowering and photosynthesis. As sessile organisms, plants have evolved to leverage phase separation for rapid sensing and response to environmental fluctuations and stress conditions. Recent studies highlight the critical role of phase separation in plant adaptation, particularly in response to abiotic stress. This review compiles the latest research on biomolecular condensates in plant biology, providing examples of their diverse functions in development, environmental adaptation, and stress responses. We propose that phase separation represents a conserved and dynamic mechanism enabling plants to adapt efficiently to ever-changing environmental conditions. Deciphering the molecular mechanisms underlying phase separation in plant stress responses opens new avenues for biotechnological strategies aimed at engineering stress-resistant crops. These advancements have significant implications for agriculture, particularly in addressing crop productivity in the face of climate change.

Improving yield-related traits by editing the promoter and distal regulatory region of heading date genes Ghd7 and PRR37 in elite rice variety Mei Xiang Zhan 2

KEY MESSAGE

We revealed that editing the promoter and distal regulatory region of the pleiotropic genes Ghd7 and PRR37 reduces their ability to delay heading date while improving their capacity to boost crop yield, offering valuable resources for rice breeding. Heading date is a crucial agronomic characteristic in rice that governs the adaptability to different latitudes and the yield of various varieties. Optimizing the heading date of superior cultivars in breeding practice can significantly broaden their potential planting areas. Ghd7 and PRR37 are pivotal genes that control heading date and enhance agronomic traits. In the elite indica rice variety Mei Xiang Zhan 2 (MXZ2), we used CRISPR/Cas9 technology to effectively generate homozygous mutant lines with a gradient change in heading date by multi-target editing the promoter and distal regulatory region of Ghd7 and PRR37. Various degrees of down-regulation of Ghd7 or PRR37 expression, impaired gene functions, and advancement of the heading date were observed in the mutant lines. Certain mutant lines exhibited an early heading date and increased yield while preserving the exceptional quality of MXZ2. Our study revealed that editing the promoter and distal regulatory region of the pleiotropic genes Ghd7 and PRR37 reduces their ability to delay heading date while improving their capacity to boost crop yield, offering valuable resources for rice breeding.

Characterization and functional analysis of CONSTANS-like 3 involved in photoperiodic flowering of Gossypium hirsutum

The CONSTANS-like (COL) family plays a pivotal role in regulating plant photoperiodic flowering pathways. Although several COLs have been characterized in Arabidopsis, their functions in cotton lack clarity. Here, GhCOL3, a gene of the COL family in cotton (Gossypium hirsutum), was cloned and characterized. GhCOL3 is located in the nucleus, and GhCOL3 was expressed in young leaves, hypocotyls, and flower organs and exhibited obvious circadian rhythms under long-day conditions. Overexpressing of GhCOL3 heterogeneously in Arabidopsis thaliana led to delayed flowering, whereas silencing of GhCOL3 in cotton using the virus-induced gene silencing system led to earlier flowering, suggesting a negative regulatory role of GhCOL3 in plant flowering. Transcriptome analysis and expression detection showed that bHLH38, bHLH100, bHLH101, and BBX31 were significantly upregulated in GhCOL3 heterogeneous overexpression lines, whereas the expression of FT was downregulated. Moreover, the expression of GhbHLH38, GhBBX31, and GhFT were significantly affected in the GhCOL3-silenced line, thus laying the foundation for elucidating the regulatory mechanism of GhCOL3 in cotton flowering.

Photoperiodic control of growth and reproduction in non-flowering plants

Photoperiodic responses shape plant fitness to the changing environment and are important regulators of growth, development, and productivity. Photoperiod sensing is one of the most important cues to track seasonal variations. It is also a major cue for reproductive success. The photoperiodic information conveyed through the combined action of photoreceptors and the circadian clock orchestrates an output response in plants. Multiple responses such as hypocotyl elongation, induction of dormancy, and flowering are photoperiodically regulated in seed plants (eg. angiosperms). Flowering plants such as Arabidopsis or rice have served as important model systems to understand the molecular players involved in photoperiodic signalling. However, photoperiodic responses in non-angiosperm plants have not been investigated and documented in detail. Genomic and transcriptomic studies have provided evidence on the conserved and distinct molecular mechanisms across the plant kingdom. In this review, we have attempted to compile and compare photoperiodic responses in the plant kingdom with a special focus on non-angiosperms.