An official website of the United States government
Abstract The precise onset of flowering is crucial to ensure successful plant reproduction. The geneFLOWERING LOCUS T(FT) encodes florigen, a mobile signal produced in leaves that initiates flowering at the shoot apical meristem. In response to seasonal changes,FTis induced in phloem companion cells located in distal leaf regions. Thus far, a detailed molecular characterization of theFT-expressing cells has been lacking. Here, we used bulk nuclei RNA-seq and single nuclei RNA (snRNA)-seq to investigate gene expression inFT-expressing cells and other phloem companion cells. Our bulk nuclei RNA-seq demonstrated thatFT-expressing cells in cotyledons and in true leaves differed transcriptionally. Within the true leaves, our snRNA-seq analysis revealed that companion cells with highFTexpression form a unique cluster in which many genes involved in ATP biosynthesis are highly upregulated. The cluster also expresses other genes encoding small proteins, including the flowering and stem growth inducer FPF1-LIKE PROTEIN 1 (FLP1) and the anti-florigen BROTHER OF FT AND TFL1 (BFT). In addition, we found that the promoters ofFTand the genes co-expressed withFTin the cluster were enriched for the consensus binding motifs of NITRATE-INDUCIBLE GARP-TYPE TRANSCRIPTIONAL REPRESSOR 1 (NIGT1). Overexpression of the paralogousNIGT1.2andNIGT1.4repressedFTexpression and significantly delayed flowering under nitrogen-rich conditions, consistent with NIGT1s acting as nitrogen-dependentFTrepressors. Taken together, our results demonstrate that majorFT-expressing cells show a distinct expression profile that suggests that these cells may produce multiple systemic signals to regulate plant growth and development.
more »
« less
An explanatory model of temperature influence on flowering through whole-plant accumulation of FLOWERING LOCUS T in Arabidopsis thaliana
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 FLOWERING LOCUS T (FT), a photoperiodic flowering regulator that is expressed in leaves. The Arabidopsis Framework Model incorporated temperature influence on leaf growth but ignored the consequences of leaf growth on and direct temperature influence of FT expression. We measured FT production in differently aged leaves and modified the model, adding mechanistic temperature influence on FT transcription, and causing whole-plant FT to accumulate with leaf growth. Our simulations suggest that in long days, the developmental stage (leaf number) at which the reproductive transition occurs is influenced by day length and temperature through FT, while temperature influences the rate of leaf production and the time (in days) the transition occurs. Further, we demonstrate that FT is mainly produced in the first 10 leaves in the Columbia (Col-0) accession, and that FT accumulation alone cannot explain flowering in conditions in which flowering is delayed. Our simulations supported our hypotheses that: (i) temperature regulation of FT, accumulated with leaf growth, is a component of thermal time, and (ii) incorporating mechanistic temperature regulation of FT can improve model predictions when temperatures change over time.
more »
« less
- Award ID(s):
- 1656076
- PAR ID:
- 10132952
- Date Published:
- Journal Name:
- in silico plants
- Volume:
- 1
- Issue:
- 1
- ISSN:
- 2517-5025
- Page Range / eLocation ID:
- diz006
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Background The 29-member Arabidopsis AHL gene family is classified into three main classes based on nucleotide and protein sequence evolutionary differences. These differences include the presence or absence of introns, type and/or number of conserved AT-hook and PPC domains. AHL gene family members are divided into two phylogenetic clades, Clade-A and Clade-B. A majority of the 29 members remain functionally uncharacterized. Furthermore, the biological significance of the DNA and peptide sequence diversity, observed in the conserved motifs and domains found in the different AHL types, is a subject area that remains largely unexplored. Results Transgenic plants overexpressing AtAHL20 flowered later than the wild type under both short and long days. Transcript accumulation analyses showed that 35S:AtAHL20 plants contained reduced FT, TSF, AGL8 and SPL3 mRNA levels. Similarly, overexpression of AtAHL20’s orthologue in Camelina sativa, Arabidopsis’ closely related Brassicaceae family member species, conferred a late-flowering phenotype via suppression of CsFT expression. However, overexpression of an aberrant AtAHL20 gene harboring a missense mutation in the AT-hook domain’s highly conserved R-G-R core motif abolished the late-flowering phenotype. Data from targeted yeast-two-hybrid assays showed that AtAHL20 interacted with itself and several other Clade-A Type-I AHLs which have been previously implicated in flowering-time regulation: AtAHL19, AtAHL22 and AtAHL29. Conclusion We showed via gain-of-function analysis that AtAHL20 is a negative regulator of FT expression, as well as other downstream flowering time regulating genes. A similar outcome in Camelina sativa transgenic plants overexpressing CsAHL20 suggest that this is a conserved function. Our results demonstrate that AtAHL20 acts as a photoperiod-independent negative regulator of transition to flowering.more » « less
-
The proper timing of flowering, which is key to maximize reproductive success and yield, relies in many plant species on the coordination between environmental cues and endogenous developmental programs. The perception of changes in day length is one of the most reliable cues of seasonal change, and this involves the interplay between the sensing of light signals and the circadian clock. Here, we describe a Brachypodium distachyon mutant allele of the evening complex protein EARLY FLOWERING 3 (ELF3). We show that the elf3 mutant flowers more rapidly than wild type plants in short days as well as under longer photoperiods but, in very long (20 h) days, flowering is equally rapid in elf3 and wild type. Furthermore, flowering in the elf3 mutant is still sensitive to vernalization, but not to ambient temperature changes. Molecular analyses revealed that the expression of a short-day marker gene is suppressed in elf3 grown in short days, and the expression patterns of clock genes and flowering time regulators are altered. We also explored the mechanisms of photoperiodic perception in temperate grasses by exposing B. distachyon plants grown under a 12 h photoperiod to a daily night break consisting of a mixture of red and far-red light. We showed that 2 h breaks are sufficient to accelerate flowering in B. distachyon under non-inductive photoperiods and that this acceleration of flowering is mediated by red light. Finally, we discuss advances and perspectives for research on the perception of photoperiod in temperate grasses.more » « less
-
Many plants are responding to increases in spring temperatures by advancing their leaf‐out and flowering times in temperate regions around the world. The magnitudes of species' sensitivities to temperature vary widely, and patterns within that variation can illuminate underlying phenological drivers related to species' life histories and local‐scale adaptations.The USA National Phenology Network (USA‐NPN) and the National Ecological Observatory Network (NEON) are two rapidly growing, taxonomically and geographically extensive phenology data resources in the USA that offer opportunities to explore emergent properties of spring phenology. Using observations of leaf‐out and flowering in temperate deciduous plant species from USA‐NPN (2009–2024) and NEON (2014–2022), we estimated species‐level flowering (n = 164) and leaf‐out (n = 136) sensitivities to temperatures of the preceding months, obtained through PRISM. We used the results to assess differences in sensitivities between the two datasets and among life history traits (e.g. introduced or native status, seasonal timing and growth habit) and to explore latitudinal patterns in sensitivity among and within species. We found significant relationships between temperature and leaf‐out phenology (2009–2024 for 109 (80%) species, ranging from −7.4 to −1.3 days/°C, and between temperature and flowering phenology for 140 (85%) species, ranging from −8.0 to −1.1 days/°C. Plant sensitivities were highly consistent among the USA‐NPN and NEON datasets, suggesting these datasets can be reasonably combined to expand the coverage of publicly available phenological data across the USA. Introduced species showed stronger sensitivity to temperature than native species for both leaf‐out (−0.8 days/°C difference) and flowering (−0.7 days/°C difference). The strongest (i.e. most negative) leaf‐out sensitivities to temperature were associated with earlier leaf‐out dates and strong flowering sensitivities. Latitudinal analyses within and across species indicate that flowering and leaf‐out sensitivities are both stronger at lower latitudes. Synthesis. Phenological ‘big data’ encompassing over 100 species across the eastern USA shows that leaf‐out and flowering occur earlier with warmer temperatures and that native species and individuals at high latitudes tend to have weaker temperature sensitivities than introduced species and more southern plants; these findings suggest adaptations within and across species to avoid leafing out and flowering under harsh environmental conditions.more » « less
-
Premise of the StudyNew growth in the spring requires resource mobilization in the vascular system at a time when xylem and phloem function are often reduced in seasonally cold climates. As a result, the timing of leaf out and/or flowering could depend on when the vascular system resumes normal function in the spring. This study investigated whether flowering time is influenced by vascular phenology in plants that flower precociously before they have leaves. MethodsFlower, leaf, and vascular phenology were monitored in pairs of precocious and non‐precocious congeners. Differences in resource allocation were quantified by measuring bud dry mass and water content throughout the year, floral hydration was modelled, and a girdling treatment completed on branches in the field. Key ResultsPrecocious flowering species invested more in floral buds the year before flowering than did their non‐precocious congeners, thus mobilizing less water in the spring, which allowed flowering before new vessel maturation. ConclusionsA shift in the timing of resource allocation in precocious flowering plants allowed them to flower before the production of mature vessels and minimized the significance of seasonal changes in vascular function to their flowering phenology. The low investment required to complete floral development in the spring when the plant vascular system is often compromised could explain why flowers can emerge before leaf out.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/https://doi.org/10.1093/insilicoplants/diz006
