Changes In Light Quality Research Articles

Dephosphorylation of bZIP59 by PP2A ensures appropriate shade avoidance response in Arabidopsis.

Changes in light quality and quantity experienced by many shade-intolerant plants grown in close proximity lead to transcriptional reprogramming and shade avoidance syndrome (SAS). Despite the importance of phosphorylation-dependent signaling in cellular physiology, phosphorylation events during SAS are largely unknown. Here, we examined shade-regulated phosphorylation events in Arabidopsis using quantitative phosphoproteomics. We confirmed shade-induced dephosphorylation of bZIP59, a basic region/leucine zipper motif (bZIP) transcription factor. Shade treatment promotes the nuclear localization of bZIP59, which can be mimicked by mutation of the phosphorylation sites on bZIP59. Phenotypic analysis identified that bZIP59 negatively regulated shade-induced hypocotyl elongation. bZIP59 repressed the shade-induced activation of certain growth-related genes, while shade increased the DNA binding of bZIP59. Furthermore, the protein phosphatase 2A (PP2A) mediated dephosphorylation of bZIP59. Our study characterized a previously unidentified mechanism by which the phytochrome B (phyB)-PP2A-bZIP59 regulatory module integrates shade signals and transcriptomes, broadening our knowledge of phosphorylation strategies for rapid adaptation to shade.

ASYMMETRIC LEAVES1 promotes leaf hyponasty in Arabidopsis by light-mediated auxin signaling.

In plants, balancing growth and environmental responses is crucial for maximizing fitness. Close proximity among plants and canopy shade, which negatively impacts reproduction, elicits morphological adjustments such as hypocotyl growth and leaf hyponasty, mainly through changes in light quality and auxin levels. However, how auxin, synthesized from a shaded leaf blade, distally induces elongation of hypocotyl and petiole cells remains to be elucidated. We demonstrated that ASYMMETRIC LEAVES1 (AS1) promotes leaf hyponasty through the regulation of auxin biosynthesis, polar auxin transport, and auxin signaling genes in Arabidopsis (Arabidopsis thaliana). AS1 overexpression leads to elongation of the abaxial petiole cells with auxin accumulation in the petiole, resulting in hyponastic growth, which is abolished by the application of an auxin transport inhibitor to the leaf blade. In addition, the as1 mutant exhibits reduced hypocotyl growth under shade conditions. We observed that AS1 protein accumulates in the nucleus in response to shade or far-red light. Chromatin immunoprecipitation analysis identified the association of AS1 with the promoters of YUCCA8 (YUC8) and INDOLE-3-ACETIC ACID INDUCIBLE 19 (IAA19). In addition, AS1 forms complexes with PHYTOCHROME INTERACTING FACTORs in the nucleus and synergistically induces YUC8 and IAA19 expression. Our findings suggest that AS1 plays a crucial role in facilitating phenotypic plasticity to the surroundings by connecting light and phytohormone action.

Cysteine residues contribute to the regulation of Arabidopsis state transition 7 kinase.

State transitions are an acclimatory response by which plants, algae, and cyanobacteria counteract photosynthetic inefficiency caused by changes in incident light quality. In plants and green algae, state transition 7 (STN7/STT7) kinase promotes state 2 transition. Conserved cysteine residues are implicated in STN7/STT7 regulation, but the precise nature of their involvement remains unclear. Here, an analysis of the STN7 thiols in vitro and a determination of their midpoint redox potential indicate that the lumenal disulfide linkage is unlikely to be redox regulated while the stromal cysteines form a regulatory intramolecular disulfide. We further show that thioredoxin f1 (Trx-f1) reduces the STN7 stromal disulfide linkage as consistent with a Trx-f1-mediated inhibition of the kinase under high light.

BZIP transcription factor responds to changes in light quality and affects saponins synthesis in Eleutherococcus senticosus

Light quality considerably influences plant secondary metabolism, yet the precise mechanism underlying its impact on Eleutherococcus senticosus remains elusive. Comprehensive metabolomic and transcriptomic analyses revealed that varying light quality alters the biosynthesis of triterpene saponins by modulating the expression of genes involved in the process in E. senticosus. Through correlation analysis of gene expression and saponin biosynthesis, we identified four light-responsive transcription factors, namely EsbZIP1, EsbZIP2, EsbZIP4, and EsbZIP5. EsbZIP transcription factors function in the nucleus, with light quality-dependent promoter activity. Except for EsbZIP2, the other EsbZIP transcription factors exhibit transcriptional self-activation. Furthermore, EsbZIP can bind to the promoter areas of genes that encode important enzymes (EsFPS, EsSS, and EsSE) involved in triterpene saponin biosynthesis, thereby regulating their expression. Overexpression of EsbZIP resultes in significant down-regulation of most downstream target genes，which leads to a decrease in saponin content. Overall, varying light quality enhances the content of triterpene saponins by suppressing the expression of EsbZIP. This study thus elucidates the molecular mechanism by which E. senticosus adjusts triterpene saponin levels in response to changes in light quality.

Impact of dye treatment as management strategy on available light may favour a highly invasive alien aquatic plant

Attempts to control massive proliferations of invasive alien aquatic plants (IAAP) are often ineffective. A renewed interest for dye treatment is emerging aiming to control the submerged macrophyte Myriophyllum heterophyllum in France. We aimed to understand the effects of dye on this plant knowing about its adaptation to low light. In a 2 × 2 factorial design experiment, we assessed the effect of a dye mixture based on Brilliant Blue (E133) and Allura Red (E129) at high and low light intensities on light quantity and quality and how this might affect the plant’s performance by measuring morphological and physiological traits. A multivariate analysis identified three groups – high light (HL) plants, plants in high light with dye (HLD) or low light (LL), and low light with dye (LLD) plants. HL plants performed well but showed stress signs, with a reduced main shoot length, a higher leaf dry matter content (LDMC) and a lower nitrogen content (N), not observed in plants grown in HLD or LL. HLD and LL plants exhibited a comparable total length growth rate to those in HL, but had lower LDMC and higher N contents. LLD plants performed poorly with the lowest growth and signs of physiological stress. Dye-induced changes in light quality only marginally affected the absorbance range of chlorophyll b, which apparently did not affect photosynthesis. Commercially available dyes currently used to control nuisance aquatic plants thus seem to have little or no effect on submerged macrophytes. The presence of dye may exacerbate negative effects of very low light intensities on the plant’s growth. However, these very low intensities would only be reached during high-water levels or in winter, periods where the dye would rapidly be diluted. During summer, however, the application of dye may protect the plant from damaging light intensities and thus not be a good management strategy to control low light adapted invasive submerged macrophytes.

A Novel 10-Base Pair Deletion in the First Exon of GmHY2a Promotes Hypocotyl Elongation, Induces Early Maturation, and Impairs Photosynthetic Performance in Soybean.

Plants photoreceptors perceive changes in light quality and intensity and thereby regulate plant vegetative growth and reproductive development. By screening a γ irradiation-induced mutant library of the soybean (Glycine max) cultivar "Dongsheng 7", we identified Gmeny, a mutant with elongated nodes, yellowed leaves, decreased chlorophyll contents, altered photosynthetic performance, and early maturation. An analysis of bulked DNA and RNA data sampled from a population segregating for Gmeny, using the BVF-IGV pipeline established in our laboratory, identified a 10 bp deletion in the first exon of the candidate gene Glyma.02G304700. The causative mutation was verified by a variation analysis of over 500 genes in the candidate gene region and an association analysis, performed using two populations segregating for Gmeny. Glyma.02G304700 (GmHY2a) is a homolog of AtHY2a in Arabidopsis thaliana, which encodes a PΦB synthase involved in the biosynthesis of phytochrome. A transcriptome analysis of Gmeny using the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed changes in multiple functional pathways, including photosynthesis, gibberellic acid (GA) signaling, and flowering time, which may explain the observed mutant phenotypes. Further studies on the function of GmHY2a and its homologs will help us to understand its profound regulatory effects on photosynthesis, photomorphogenesis, and flowering time.

The PHYB–FOF2–VOZ2 module functions to fine-tune flowering in response to changes in light quality by modulating FLC expression in Arabidopsis

Proper timing of flowering under different environmental conditions is critical for plant propagation. Light quality is a pivotal environmental cue that plays a critical role in flowering regulation. Plants tend to flower late under light with a high red (R)/far-red (FR) light ratio but early under light with a low R/FR light ratio. However, how plants fine-tune flowering in response to changes in light quality is not well understood. Here, we demonstrate that F-box of Flowering 2 (FOF2), an autonomous pathway–related regulator, physically interacts with VASCULAR PLANT ONE-ZINC FINGER 1 and 2 (VOZ1 and VOZ2), which are direct downstream factors of the R/FR light receptor phytochrome B (PHYB). We show that PHYB physically interacts with FOF2, mediates stabilization of the FOF2 protein under FR light and end-of-day FR light, and enhances FOF2 binding to VOZ2, which leads to degradation of VOZ2 by SCFFOF2 E3 ligase. By contrast, PHYB mediates degradation of FOF2 protein under R light and end-of-day R light. Genetic interaction studies demonstrated that FOF2 functions downstream of PHYB to promote FLC expression and inhibit flowering under both high R/FR light and simulated shade conditions, processes that are partially dependent on VOZ proteins. Taken together, our findings suggest a novel mechanism whereby plants fine-tune flowering time through a PHYB–FOF2–VOZ2 module that modulates FLC expression in response to changes in light quality.

Light quality induces a shift in coccosphere morphology in Scyphosphaera apsteinii.

The coccolithophore Schyphosphaera apsteinii produces distinct coccolith morphotypes and offers a unique insight into coccolith calcification, as the number of lopadoliths per cell increases under low light intensities. This study employs S. apsteinii to investigate the acclimated impact of light intensity and wavelength on cell physiology and coccosphere morphology. Our findings reveal a marked increase in lopadolith production when grown under reduced light intensity, with lower growth rates, higher chlorophyll concentration and elevated net photosynthetic rates. Reduced blue-light also caused an increase in lopadolith numbers, elevated chlorophyll concentrations and net photosynthetic rates. Conversely, such responses are less pronounced under reduced red-light. Moreover, reduced blue- and red-light treatments exhibited enhanced growth rates compared to the light-replete control, despite a reduction in light intensity. Our findings suggest that changes in light quality cause a shift in the coccosphere morphology, affecting cell physiology and potentially aiding light harvesting in S. apsteinii.

Investigating the Effects of Full-Spectrum LED Lighting on Strawberry Traits Using Correlation Analysis and Time-Series Prediction.

In crop cultivation, particularly in controlled environmental agriculture, light quality is one of the most critical factors affecting crop growth and harvest. Many scholars have studied the effects of light quality on strawberry traits, but they have used relatively simple light components and considered only a small number of light qualities and traits in each experiment, and the results were not complete or objective. In order to comprehensively investigate the effects of different light qualities from 350 nm to 1000 nm on strawberry traits to better predict the future growth trend of strawberries under different light qualities, we proposed a new approach. We introduced Spearman's rank correlation coefficient to handle complex light quality variations and multiple traits, preprocessed the cultivation data through the CEEDMAN method, and predicted them using the Informer network. We took 500 strawberry plants as samples and cultivated them in 72 groups of dynamically changing light qualities. Then, we recorded the growth changes and formed training and testing sets. Finally, we discussed the correlation between light quality and plant trait changes in consistency with current studies, and the proposed prediction model achieved the best performance in the prediction task of nine plant traits compared with the comparison models. Thus, the validity of the proposed method and model was demonstrated.

Temporal control of the Aux/IAA genes BnIAA32 and BnIAA34 mediates Brassica napus dual shade responses.

Precise responses to changes in light quality are crucial for plant growth and development. For example, hypocotyls of shade-avoiding plants typically elongate under shade conditions. Although this typical shade-avoidance response (TSR) has been studied in Arabidopsis (Arabidopsis thaliana), the molecular mechanisms underlying shade tolerance are poorly understood. Here we report that B. napus (Brassica napus) seedlings exhibit dual shade responses. In addition to the TSR, B. napus seedlings also display an atypical shade response (ASR), with shorter hypocotyls upon perception of early-shade cues. Genome-wide selective sweep analysis indicated that ASR is associated with light and auxin signaling. Moreover, genetic studies demonstrated that phytochrome A (BnphyA) promotes ASR, whereas BnphyB inhibits it. During ASR, YUCCA8 expression is activated by early-shade cues, leading to increased auxin biosynthesis. This inhibits hypocotyl elongation, as young B. napus seedlings are highly sensitive to auxin. Notably, two non-canonical AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) repressor genes, BnIAA32 and BnIAA34, are expressed during this early stage. BnIAA32 and BnIAA34 inhibit hypocotyl elongation under shade conditions, and mutations in BnIAA32 and BnIAA34 suppress ASR. Collectively, our study demonstrates that the temporal expression of BnIAA32 and BnIAA34 determines the behavior of B. napus seedlings following shade-induced auxin biosynthesis.

Preliminary Examinations of Phenotypical Changes in Land-Based Long-Term Tumble Culture of Palmaria palmata

Within the last decade, the red alga P. palmata gained increasing interest as a food additive in Europe. Traditionally, P. palmata is harvested from wild stocks, but higher biomass demands request a shift towards industrial cultivation of this species. Using a land-based tumble culture approach, we have successfully grown P. palmata via vegetative propagation over a 2-year period. One year after the initial setup, phenotypic changes represented in the formation of randomly shaped, mostly circular galls and homogeneous greenish–white spots with significantly reduced photosynthetic activity were observed on the algal thalli. With progressing time, galls increased into large flat or sunken structures, whereas the tissue in the center of the greenish–white spots weakened. In later stages, the weakened tissue is disrupted, forming holes in the thallus. In this study, we present observations, microscopy analysis, PAM results, and biotechnological approaches to describe a possible infection of P. palmata. Test results showed that light quantity might be the most important factor for the propagation behavior of the infection, whereas the pH level might be secondary, and the nutrient level and biomass density might be of minor relevance. Similarly, changes in light quality could also influence the occurrence of pathological changes in P. palmata.

EMS-induced mutagenesis in Choy sum (Brassica chinensis var. parachinensis) and selection for low light tolerance using abiotic stress indices

BackgroundChoy Sum (Brassica rapa ssp. chinensis var. parachinensis), grown in a controlled environment, is vulnerable to changes in indoor light quality and displays distinct photo-morphogenesis responses. The scarcity of Choy Sum germplasm for indoor cultivation necessitates the development of new cultivars. Hence, this study attempted to develop mutants through chemical mutagenesis and select low-light-tolerant mutants by using abiotic stress tolerance indices.ResultsA mutant population of Choy Sum created using 1.5% ethyl methane sulfonate (EMS) at 4 h was manually pollinated to obtain the M2 generation. 154 mutants with reduced hypocotyl length were initially isolated from 3600 M2 seedlings screened under low light (R: FR = 0.5). Five mutants that showed reduced plant height at mature stages were selected and screened directly for shade tolerance in the M3 generation. Principal component analysis based on phenotypic data distinguished the M3 mutants from the wild type. Abiotic stress tolerance indices such as relative stress index (RSI), stress tolerance index (STI), geometric mean productivity (GMP), yield stability index (YSI), and stress resistance index (SRI) showed significant (P < 0.05), and positive associations with leaf yield under shade. M3-12–2 was selected as a shade-tolerant mutant based on high values of STI, YSI, and SRI with low values for tolerance (TOL) and stress susceptibility index (SSI).ConclusionsThe results demonstrate that mutation breeding can be used to create dominant mutants in Choy Sum. Furthermore, we show that screening for low light and selection based on abiotic tolerance indices allowed the identification of mutants with high resilience under shade. This method should apply to developing new cultivars in other crop plants that can be suitable for controlled environments with stable yield performance.

How tree stand phenology determines understorey senescence - a case study from boreal forests

Leaf fall in the autumn opens the forest canopy, allowing more solar radiation to be transmitted to the forest floor. Those understorey species that remain physiologically active into the autumn may benefit from the sunlight received by extending their growing season, to assimilate additional carbon while conditions remain favourable. We monitored leaf water and pigment content, as well as photosynthetic capacity in understorey species growing in adjacent stands differing in their canopy tree species. Leaf fall, transmitted light, and microclimate were monitored in each stand. We found that overstorey leaf fall started earlier in the birch (Betula pendula, L.), than in the oak (Quercus robur, L.) stand, and light transmission changed accordingly. Concurrently, understorey leaf senescence was generally earlier in the birch than in the oak stand, itself earlier than in the evergreen spruce stand (Picea abies, L. H. Karst.). Neither atmospheric CO2, humidity, nor temperature differed between stands. A change in light quality and/or increase in quantity following leaf fall drove the difference in the timing of senescence in the understorey. Understorey species with later senescence were able to use the increased light more after leaf fall. Together these findings help to provide a mechanistic foundation to predict how ecosystem functioning and ultimately carbon balance will be impacted by phenological shifts in response to global changes.

Modeling functional relationships between morphogenetically active radiation and photosynthetic photon flux density in mango tree crown

Light is a key factor in plant ecophysiological modeling because of its crucial effects on plant growth and development. However, solar light quantity and quality change with environmental factors such as sky condition and solar elevation. When passing through a tree crown, light is modified by its interaction with the phytoelements, leaves and axes. This leads to a variability of light quantity and quality within the crown, with consequences on light-related processes such as photosynthesis and photomorphogenesis. We evaluated the effects of positional (depth within the crown) and environmental (sky condition, solar elevation) factors on light quantity and quality within the crown of the tropical evergreen mango tree. Functional relationships were modeled between morphogenetically active radiation variables that describe light quality [narrowband red (Rn), narrowband far-red (FRn), the ratio ζ=Rn : FRn, and UVA-blue (UVA-BL)] and light quantity [photosynthetic photon flux density (PPFD) and relative transmitted PPFD (TrPPFD)]. Light quantity and quality varied within the mango tree crown in a wide range similar to that of a forest. This variability was structured by the depth within the crown as well as by sky condition and solar elevation. Linear relationships linked Rn, FRn and UVA-BL to PPFD, and non-linear relationships linked ζ to TrPPFD. These relationships were strong, accurate and unbiased. They were affected by positional and environmental factors. The results suggested that these relationships were shaped by the characteristics of incident solar light and/or by the interactions between light and phytoelements. Two consequences of interest emerged from this research: i) the modeled relationships allow to infer light quality, that is difficult and time-consuming to simulate, from light quantity modeling within a tree crown, and ii) sky condition and solar elevation should be considered to improve light modeling within a tree crown.

Artificial light quality changes colonization ability of biocontrol agents under greenhouse conditions

Artificial light quality changes colonization ability of biocontrol agents under greenhouse conditions

Genetic and physiological responses to light quality in a deep ocean ecotype of Ostreococcus, an ecologically important photosynthetic picoeukaryote.

Phytoplankton are exposed to dramatic variations in light quality when cells are carried by upwelling or downwelling currents or encounter sediment. We investigated the potential impact of light quality changes in Ostreococcus, a key marine photosynthetic picoeukaryote, by analysing changes in its transcriptome, pigment content, and photophysiology after acclimation to monochromatic red, green, or blue light. The clade B species RCC809, isolated from the deep euphotic zone of the tropical Atlantic Ocean, responded to blue light by accelerating cell division at the expense of storage reserves and by increasing the relative level of blue-light-absorbing pigments. It responded to red and green light by increasing its potential for photoprotection. In contrast, the clade A species OTTH0595, which originated from a shallow water environment, showed no difference in photosynthetic properties and minor differences in carotenoid contents between light qualities. This was associated with the loss of candidate light-quality responsive promoter motifs identified in RCC809 genes. These results demonstrate that light quality can have a major influence on the physiology of eukaryotic phytoplankton and suggest that different light quality environments can drive selection for diverse patterns of responsiveness and environmental niche partitioning.

Biosynthesis of gibberellin-related compounds modulates far-red light responses in the liverwort Marchantia polymorpha.

Gibberellins (GAs) are key phytohormones that regulate growth, development, and environmental responses in angiosperms. From an evolutionary perspective, all major steps of GA biosynthesis are conserved among vascular plants, while GA biosynthesis intermediates such as ent-kaurenoic acid (KA) are also produced by bryophytes. Here, we show that in the liverwort Marchantia polymorpha, KA and GA12 are synthesized by evolutionarily conserved enzymes, which are required for developmental responses to far-red light (FR). Under FR-enriched conditions, mutants of various biosynthesis enzymes consistently exhibited altered thallus growth allometry, delayed initiation of gametogenesis, and abnormal morphology of gamete-bearing structures (gametangiophores). By chemical treatments and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses, we confirmed that these phenotypes were caused by the deficiency of some GA-related compounds derived from KA, but not bioactive GAs from vascular plants. Transcriptome analysis showed that FR enrichment induced the up-regulation of genes related to stress responses and secondary metabolism in M. polymorpha, which was largely dependent on the biosynthesis of GA-related compounds. Due to the lack of canonical GA receptors in bryophytes, we hypothesize that GA-related compounds are commonly synthesized in land plants but were co-opted independently to regulate responses to light quality change in different plant lineages during the past 450 million years of evolution.

Precise patterning of carbon films on polyethylene terephthalate polymer substrates using femtosecond lasers

A carbon film on a polyethylene terephthalate (PET) substrate is a novel type of flexible laminated material with unique mechanical and electrical properties, making it suitable for the fabrication of various flexible electronic components. However, due to its micron-level thickness, conventional mechanical processing methods are incapable of precisely removing the carbon film without damaging the substrate. Femtosecond laser processing is an advanced technique for achieving precise etching of thin-film materials due to its non-contact, high-precision, and minimal thermal effects. Therefore, we use femtosecond lasers to achieve precision etching of carbon resistive films on PET substrates to minimize substrate damage. In this study, a series of orthogonal and single-factor experiments were conducted to optimize the laser processing parameters. Various measurement and characterization methods, including X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, ultraviolet–visible spectroscopy, and confocal microscopy, were employed to analyze the removal of the carbon layer, changes in light transmittance, surface quality, and chemical composition of the processed substrate. Furthermore, the mechanisms of carbon film removal and PET substrate damage are explained.

Different LED light intensity and quality change perennial ryegrass (Lolium perenne L.) physiological and growth responses and water and energy consumption.

Light intensity and spectral composition highly affect plant physiology, growth, and development. According to growing conditions, each species and/or cultivar has an optimum light intensity to drive photosynthesis, and different light spectra trigger photosynthetic responses and regulate plant development differently. For the maintenance of natural sports pitches, namely professional football competitions, turf quality is a key condition. Due to the architecture of most football stadiums, the lawns receive low intensities of natural light, so supplementary artificial lighting above the turf is required. The use of light-emitting diodes (LEDs) can have a higher cost-benefit ratio than traditional high-pressure sodium lamps. The continuous emission spectrum, combined with high spectral selectivity and adjustable optical power, can be used to optimize plant growth and development. Thus, perennial ryegrass (Lolium perenne L.) plants, commonly used for lawns, were primarily grown at three different intensities (200, 300, and 400 μmol m-2 s-1) of cool white light. Despite the higher water and energy consumption, 400 μmol m-2 s-1 maximizes the plant's efficiency, with higher photosynthetic rates and foliar pigment concentration, and more foliar soluble sugars and aboveground biomass accumulation. Then, it was evaluated the perennial ryegrass (Double and Capri cultivars) response to different spectral compositions [100% cool white (W), 80% Red:20% Blue (R80:B20), 90% Red:10% Blue (R90:B10), and 65% Red:15% Green:20% Blue (R65:G15:B20)] at 400 μmol m-2 s-1. Both cultivars exhibited similar responses to light treatments. In general, W contributed to the better photosynthetic performance and R90:B10 to the worst one. Water consumption and aboveground biomass were equal in all light treatments. R80:B20 allows energy savings of 24.3% in relation to the W treatment, showing a good compromise between physiological performance and energy consumption.

PIF7-mediated epigenetic reprogramming promotes the transcriptional response to shade inArabidopsis.

For shade-intolerant plants, changes in light quality through competition from neighbors trigger shade avoidance syndrome (SAS): a series of morphological and physiological adaptations that are ultimately detrimental to plant health and crop yield. Phytochrome-interacting factor 7 (PIF7) is a major transcriptional regulator of SAS in Arabidopsis; however, how it regulates gene expression is not fully understood. Here, we show that PIF7 directly interacts with the histone chaperone anti-silencing factor 1 (ASF1). The ASF1-deprived asf1ab mutant showed defective shade-induced hypocotyl elongation. Histone regulator homolog A (HIRA), which mediates deposition of the H3.3 variant into chromatin, is also involved in SAS. RNA/ChIP-sequencing analyses identified the role of ASF1 in the direct regulation of a subset of PIF7 target genes. Furthermore, shade-elicited gene activation is accompanied by H3.3 enrichment, which is mediated by the PIF7-ASF1-HIRA regulatory module. Collectively, our data reveal that PIF7 recruits ASF1-HIRA to increase H3.3 incorporation into chromatin to promote gene transcription, thus enabling plants to effectively respond to environmental shade.