S-scheme carbon doped-TiO2/ZnIn2S4 heterojunction for enhanced photocatalytic degradation of microcystin-LR and hydrogen evolution.

Photocatalytic degradation of pollutants coupled with hydrogen (H2) evolution has emerged as a promising solution for environmental and energy crises. However, the fast recombination of photoexcited electrons and holes limits photocatalytic activities. Herein, an S-scheme heterojunction carbon doped-TiO2/ZnIn2S4 (C-TiO2/ZnIn2S4) was designed by substituting oxygen sites within C-TiO2 by ZnIn2S4. Under visible light irradiation, the optimal C-TiO2/ZnIn2S4 exhibits a higher degradation efficiency (88.6%) of microcystin-LR (MC-LR), compared to pristine C-TiO2 (72.9%) and ZnIn2S4 (66.8%). Furthermore, the H2 yield of the C-TiO2/ZnIn2S4 reaches 1526.9 µmol g-1 h-1, which is 3.83 times and 2.87 times that of the C-TiO2 and ZnIn2S4, respectively. Experimental and theoretical investigations reveal that an internal electric field (IEF) informed in the C-TiO2/ZnIn2S4 heterojunction, accelerates the separation of photogenerated charge pairs, thereby enhancing photocatalytic efficiency of MC-LR degradation and H2 production. This work highlights a new perspective on the development of high-performance photocatalysts for wastewater treatment and H2 generation.

Carotid Vessel Wall Segmentation Through Domain Aligner, Topological Learning, and Segment Anything Model for Sparse Annotation in MR Images.

Medical image analysis poses significant challenges due to limited availability of clinical data, which is crucial for training accurate models. This limitation is further compounded by the specialized and labor-intensive nature of the data annotation process. For example, despite the popularity of computed tomography angiography (CTA) in diagnosing atherosclerosis with an abundance of annotated datasets, magnetic resonance (MR) images stand out with better visualization for soft plaque and vessel wall characterization. However, the higher cost and limited accessibility of MR, as well as time-consuming nature of manual labeling, contribute to fewer annotated datasets. To address these issues, we formulate a multi-modal transfer learning network, named MT-Net, designed to learn from unpaired CTA and sparsely-annotated MR data. Additionally, we harness the Segment Anything Model (SAM) to synthesize additional MR annotations, enriching the training process. Specifically, our method first segments vessel lumen regions followed by precise characterization of carotid artery vessel walls, thereby ensuring both segmentation accuracy and clinical relevance. Validation of our method involved rigorous experimentation on publicly available datasets from COSMOS and CARE-II challenge, demonstrating its superior performance compared to existing state-of-the-art techniques.

Recent Advances of Green Electricity Generation: Potential in Solar Interfacial Evaporation System.

Solar-driven interfacial evaporation (SDIE) has played a pivotal role in optimizing water-energy utilization, reducing conventional power costs, and mitigating environmental impacts. The increasing emphasis on the synergistic cogeneration of water and green electricity through SDIE is particularly noteworthy. However, there is a gap of existing reviews that have focused on the mechanistic understanding of green power from water-electricity cogeneration (WEC) systems, the structure-activity relationship between efficiency of green energy utilization in WEC and material design in SDIE. Particularly, it lacks a comprehensive discussion to address the challenges faced in these areas along with potential solutions. Therefore, this review aims to comprehensively assess the progress and future perspective of green electricity from WEC systems by investigating the potential expansion of SDIE. First, it provides a comprehensive overview about material rational design, thermal management, and water transportation tunnels in SDIE. Then, it summarizes diverse energy sources utilized in the SDIE process, including steaming generation, photovoltaics, salinity gradient effect, temperature gradient effect, and piezoelectric effect. Subsequently, it explores factors that affect generated green electricity efficiency in WEC. Finally, this review proposes challenges and possible solution in the development of WEC.

Rice husk hydrochar prepared by hydrochloric acid assisted hydrothermal carbonization for levofloxacin removal in bioretention columns.

Hydrochars are promising adsorbents in pollutant removal for water treatment. Herein, hydrochloric acid (HCl) co-hydrothermally treated hydrochars were prepared from rice husk biomass at 180 °C via a one-step hydrothermal method. Adsorption behaviors of levofloxacin (LVX) on hydrochars were evaluated. The specific surface area and pore volume of the hydrochar synthesized in 5 mol/L HCl (5H-HC) were almost 17 and 8 times of untreated hydrochar, respectively. The 5H-HC sample exhibited the highest LVX adsorption capability at room temperature (107 mg/g). Thermodynamic experimental results revealed that adsorption was a spontaneous endothermic process. Yan model provided the best description of the breakthrough behavior of LVX in bioretention column, indicating that the adsorption on the samples involved several rate-limiting factors including diffusion and mass transfer. The results show that facile HCl co-hydrothermal carbonization of waste biomass can produce novel hydrochars with high LVX adsorption ability.

FLZ13 interacts with FLC and ABI5 to negatively regulate flowering time in Arabidopsis.

The transition from vegetative to reproductive growth, known as flowering, is a critical developmental process in flowering plants to ensure reproductive success. This process is strictly controlled by various internal and external cues; however, the underlying molecular regulatory mechanisms need to be further characterized. Here, we report a plant-specific protein, FCS-LIKE ZINC FINGER PROTEIN 13 (FLZ13), which functions as a hitherto unknown negative modulator of flowering time in Arabidopsis thaliana. Biochemical analysis showed that FLZ13 directly interacts with FLOWERING LOCUS C (FLC), a major flowering repressor, and that FLZ13 largely depends on FLC to repress the transcription of two core flowering integrators: FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1. In addition, FLZ13 works together with ABSCISIC ACID INSENSITIVE 5 to activate FLC expression to delay flowering. Taken together, our findings suggest that FLZ13 is an important component of the gene regulatory network for flowering time control in plants.

2D/2D Bi2MoO6/CoAl LDH S-scheme heterojunction for enhanced removal of tetracycline: Performance, toxicity, and mechanism.

In this paper, the two-dimensional (2D) layered CoAl LDH (CoAl) was coupled with Bi2MoO6 (BMO) nanoplate and used for tetracycline (TC) degradation. Based on the results of UV-visible diffuse reflectance spectrum (UV-vis DRS), Motty-Schottky curves, and in situ X-ray photoelectron spectroscopy (XPS), a novel 2D/2D Bi2MoO6/CoAl LDH S-scheme heterojunction photocatalyst was built. The photodegradation rate constant of TC by the optimized sample BMO/CoAl30 was 3.637 × 10-2 min-1, which was 1.26 times and 4.01 times higher than that of Bi2MoO6 and CoAl LDH, respectively. The favorable photocatalytic performance of the heterojunction was attributed to the increased interfacial contact area of the 2D/2D structure. Besides, the transfer of photogenerated electrons from Bi2MoO6 to CoAl LDH under the effect of the built-in electric field (BIEF) reduced the recombination of photogenerated carriers and further improved the photocatalytic performance. The reactive species of h+, ·O2-, and 1O2 exhibited critical roles to degrade TC molecules by reactive radicals capture experiments and electron spin resonance (ESR) tests. The intermediate products of TC degradation and toxicity of intermediates were analyzed by liquid chromatography-mass spectrometer (LC-MS) and Toxicity Estimation Software Tool (T.E.S.T). Additionally, the BMO/CoAl composite photocatalysts showed high stability and environmental tolerance during the testing of cycles and environmental impacts with various water sources, organic contaminants, initial pH, and inorganic ions. This work provides a new protocol for designing and constructing novel 2D/2D S-scheme heterojunction photocatalysts for wastewater treatment.

Autophagy contributes to positive feedback regulation of SnRK1 signaling in plants.

SnRK1 (SNF1-related protein kinase 1) is a plant ortholog of yeast Snf1 and mammalian adenosine monophosphate-activated protein kinase (AMPK) that acts as a positive regulator of macroautophagy/autophagy. However, whether and how the autophagy pathway modulates SnRK1 activity remains elusive. Recently, we identified a clade of plant-specific FLZ (FCS-like zinc finger) proteins as novel ATG8 (autophagy-related 8)-interacting partners in Arabidopsis thaliana. These AtFLZs, which mainly localize on the surface of mitochondria, can inhibit SnRK1 signaling by repressing the T-loop phosphorylation of its catalytic α subunits, thereby negatively regulating carbon starvation-induced autophagy and plant tolerance to energy deprivation. Upon energy starvation, autophagy is activated to mediate the degradation of these AtFLZs, thus relieving their repression of SnRK1. More importantly, the ATG8-FLZ-SnRK1 regulatory axis appears to be functionally conserved during seed plant evolution. These findings highlight the positive role of autophagy in SnRK1 signaling activation under energy-limiting conditions in plants.Abbreviations: ADS, AIMs docking site; AIM, ATG8-interacting motif; AMPK, adenosine monophosphate-activated protein kinase; ATG, autophagy-related; ESCRT, endosomal sorting complexes required for transport; FLZ, FCS-like zinc finger protein; FREE1, FYVE DOMAIN PROTEIN REQUIRED FOR ENDOSOMAL SORTING 1; RAPTOR, REGULATORY-ASSOCIATED PROTEIN OF TOR; Snf1, SUCROSE NON-FERMENTING 1; SnRK1, SNF1-related kinase 1; TOR, TARGET OF RAPAMYCIN.

A positive feedback regulation of SnRK1 signaling by autophagy in plants.

SnRK1, an evolutionarily conserved heterotrimeric kinase complex that acts as a key metabolic sensor in maintaining energy homeostasis in plants, is an important upstream activator of autophagy that serves as a cellular degradation mechanism for the healthy growth of plants. However, whether and how the autophagy pathway is involved in regulating SnRK1 activity remains unknown. In this study, we identified a clade of plant-specific and mitochondria-localized FCS-like zinc finger (FLZ) proteins as currently unknown ATG8-interacting partners that actively inhibit SnRK1 signaling by repressing the T-loop phosphorylation of the catalytic α subunits of SnRK1, thereby negatively modulating autophagy and plant tolerance to energy deprivation caused by long-term carbon starvation. Interestingly, these AtFLZs are transcriptionally repressed by low-energy stress, and AtFLZ proteins undergo a selective autophagy-dependent pathway to be delivered to the vacuole for degradation, thereby constituting a positive feedback regulation to relieve their repression of SnRK1 signaling. Bioinformatic analyses show that the ATG8-FLZ-SnRK1 regulatory axis first appears in gymnosperms and seems to be highly conserved during the evolution of seed plants. Consistent with this, depletion of ATG8-interacting ZmFLZ14 confers enhanced tolerance, whereas overexpression of ZmFLZ14 leads to reduced tolerance to energy deprivation in maize. Collectively, our study reveals a previously unknown mechanism by which autophagy contributes to the positive feedback regulation of SnRK1 signaling, thereby enabling plants to better adapt to stressful environments.

ABI5-FLZ13 module transcriptionally represses growth-related genes to delay seed germination in response to ABA.

The bZIP transcription factor ABSCISIC ACID INSENSITIVE5 (ABI5) is a master regulator of seed germination and post-germinative growth in response to abscisic acid (ABA), but the detailed molecular mechanism by which it represses plant growth remains unclear. In this study, we used proximity labeling to map the neighboring proteome of ABI5 and identified FCS-LIKE ZINC FINGER PROTEIN 13 (FLZ13) as a novel ABI5 interaction partner. Phenotypic analysis of flz13 mutants and FLZ13-overexpressing lines demonstrated that FLZ13 acts as a positive regulator of ABA signaling. Transcriptomic analysis revealed that both FLZ13 and ABI5 downregulate the expression of ABA-repressed and growth-related genes involved in chlorophyll biosynthesis, photosynthesis, and cell wall organization, thereby repressing seed germination and seedling establishment in response to ABA. Further genetic analysis showed that FLZ13 and ABI5 function together to regulate seed germination. Collectively, our findings reveal a previously uncharacterized transcriptional regulatory mechanism by which ABA mediates inhibition of seed germination and seedling establishment.

A non-canonical role of ATG8 in Golgi recovery from heat stress in plants.

Above-optimal growth temperatures, usually referred to as heat stress (HS), pose a challenge to organisms' survival as they interfere with essential physiological functions and disrupt cellular organization. Previous studies have elucidated the complex transcriptional regulatory networks involved in plant HS responses, but the mechanisms of organellar remodelling and homeostasis during plant HS adaptations remain elusive. Here we report a non-canonical function of ATG8 in regulating the restoration of plant Golgi damaged by HS. Short-term acute HS causes vacuolation of the Golgi apparatus and translocation of ATG8 to the dilated Golgi membrane. The inactivation of the ATG conjugation system, but not of the upstream autophagic initiators, abolishes the targeting of ATG8 to the swollen Golgi, causing a delay in Golgi recovery after HS. Using TurboID-based proximity labelling, we identified CLATHRIN LIGHT CHAIN 2 (CLC2) as an interacting partner of ATG8 via the AIM-LDS interface. CLC2 is recruited to the cisternal membrane by ATG8 to facilitate Golgi reassembly. Collectively, our study reveals a hitherto unanticipated process of Golgi stack recovery from HS in plant cells and uncovers a previously unknown mechanism of organelle resilience involving ATG8.

Mixture screening strategy of efficient transition metal heteronuclear dual-atom electrocatalysts toward nitrogen fixation.

To rapidly design nitrogen reduction reaction (NRR) electrocatalysts with superior activity and selectivity is a great challenge. Herein, we propose a simple mixture strategy including three screening steps and a descriptor to predict NRR electrocatalysts with outstanding activity and selectivity based on density functional theory (DFT). Twenty-eight candidate transition-metal dimers anchored on nitrogen-doped graphene were systematically investigated through our mixture strategy. The results show that VRu-NC exhibits a high NRR activity and suppression of the competitive hydrogen evolution reaction (HER) following the mixed mechanism with a favorable limiting potential (UL) of -0.21 V. Finally, the mechanism of the catalytic reaction pathway was investigated according to the profile of atomic orbitals and electronic properties. This work proposes a feasible strategy for rapid screening of the high-performance of double atomic electrocatalysts with excellent activity and selectivity for the NRR.

Step scheme nickel-aluminium layered double hydroxides/biochar heterostructure photocatalyst for synergistic adsorption and photodegradation of tetracycline.

Improving the adsorption ability of layered double hydroxide (LDH) has been considered as a promising strategy to promote its photodegradation of aqueous pollutants. In this work, nickel-aluminium layered double hydroxides (NiAl-LDH)/biochar nanocomposites were prepared using a simple coprecipitation method, and then applied in synergistic adsorption-photodegradation of tetracycline (TC) in aqueous solutions. In addition, the governing TC removal mechanisms by the nanocomposites were revealed. All NiAl-LDH/BC samples showed strong adsorption and photodegradation of TC. The Langmuir maximum TC adsorption capacity of optimized NiAl-LDH/BC-0.5 reached 124.2 mg/g, which was much better than that of NiAl-LDH (56.1 mg/g) and biochar (11.1 mg/g). Besides, TC photodegradation rate constant of NiAl/BC-0.5 was 3.6 and 4.4 times of that of NiAl-LDH and BC, respectively. The NiAl/BC-0.5 exhibited the maximum TC adsorption-photodegradation efficiency 94.4% in 90 min compared to NiAl-LDH (73.7%) and BC (48.2%). The rate constant of modified Elovich kinetic model for synergistic adsorption and photodegradation on NiAl/BC-0.5 (9.477 min-1) was the highest among the composites. The NiAl-LDH/BC had significantly larger BET surface areas than NiAl-LDH and BC. The step scheme (S-scheme) heterostructures were constructed on the interface of BC and NiAl-LDH in nanocomposites, which facilitated the transfer of photo-induced charges. This work demonstrates that combination of NiAl-LDH and biochar can create synergy for TC adsorption-photodegradation, which is a promising and green strategy.

Arabidopsis flowering integrator SOC1 transcriptionally regulates autophagy in response to long-term carbon starvation.

Autophagy is a highly conserved, self-digestion process that is essential for plant adaptations to various environmental stresses. Although the core components of autophagy in plants have been well established, the molecular basis for its transcriptional regulation remains to be fully characterized. In this study, we demonstrate that SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), a MADS-box family transcription factor that determines flowering transition in Arabidopsis, functions as a transcriptional repressor of autophagy. EMSAs, ChIP-qPCR assays, and dual-luciferase receptor assays showed that SOC1 can bind to the promoters of ATG4b, ATG7, and ATG18c via the conserved CArG box. qRT-PCR analysis showed that the three ATG genes ATG4b, ATG7, and ATG18c were up-regulated in the soc1-2 mutant. In line with this, the mutant also displayed enhanced autophagy activity, as revealed by increased autophagosome formation and elevated autophagic flux compared with the wild type. More importantly, SOC1 negatively affected the tolerance of plants to long-term carbon starvation, and this process requires a functional autophagy pathway. Finally, we found that SOC1 was repressed upon carbon starvation at both the transcriptional and protein levels. Overall, our study not only uncovers an important transcriptional mechanism that contributes to the regulation of plant autophagy in response to nutrient starvation, but also highlights novel cellular functions of the flowering integrator SOC1.

Ball-milled bismuth oxybromide/biochar composites with enhanced removal of reactive red owing to the synergy between adsorption and photodegradation.

In this paper, bismuth oxybromide (BiOBr)/biochar composites were synthesized by a facile ball milling method for synergistic adsorption and photodegradation of Reactive red 120 (RR120). The characterizations show that ball milling changed the degree of crystallization, increased the surface area, and promoted the charge transfer ability of biochar. The 70% BiOBr/BC composite showed the best removal efficiency for RR120 removal with or without light illumination, which proves its enhanced removal ability by adsorption and photodegradation. The biochar is served as a support of BiOBr for preventing its aggregation and a transporter of charges for promoting the separation of photo-induced carriers in composites. BiOBr can release the adsorption sites on the surface of composites by degradation, which facilitated the RR120 removal and regenerated the photocatalyst for reusing. The strong interactions between BiOBr and biochar in composites resulted from ball milling were beneficial for the charge transfer and synergistic removal of adsorption and degradation. Findings of this work indicate that ball milling method is an effective method to prepare highly efficient biochar-based composites for RR120 removal through synergistic adsorption and photodegradation.

Self-supported nickel-doped molybdenum carbide nanoflower clusters on carbon fiber paper for an efficient hydrogen evolution reaction.

Developing an efficient, stable and low-cost noble-metal-free electrocatalyst for the hydrogen evolution reaction (HER) is an effective way to alleviate the energy crisis. Herein, we report a simple and facile approach to synthesize self-supported Ni-doped Mo2C via a molten salt method. By optimizing the content of Ni, the concentration of Ni(NO3)2, and the annealing time, self-supported nanoflower-like electrocatalysts composed of ultrathin nanosheets on carbon fiber paper (CFP) can be achieved. Such a fluffy and porous nanoflower-like structure has a large specific surface area, which can expose many active sites, and promote charge transfer; moreover, all of the above is beneficial for improving the HER performance. Density functional theory (DFT) calculations reveal that the doping of Ni leads to a down shift of the value of the d band center (εd), so that the adsorbed hydrogen (Hads) is easier to desorb from the catalyst surface, thus leading to an enhanced intrinsic catalytic activity of Ni doped Mo2C based catalysts. As a result, Mo2C-3 M Ni(NO3)2/CFP with a nanoflower-like structure prepared at 1000 °C for 6 h exhibits the best electrocatalytic performance for the HER in 0.5 M H2SO4, with a low overpotential of 56 mV (at j = 10 mA cm-2) and a Tafel slope (27.4 mV dec-1) comparable to that of commercial Pt/C (25.8 mV dec-1). The excellent performance surpasses most of the noble-metal-free electrocatalysts. In addition, the outstanding long-term durability of Mo2C-3 M Ni(NO3)2/CFP is demonstrated by showing no obvious fluctuations during 35 h of the HER testing. This work provides a simple and facile strategy for the preparation of nanoelectrocatalysts with high specific surface areas and high catalytic activities, both of which promote an efficient HER.

Genome-wide Identification and Characterization of FCS-Like Zinc Finger (FLZ) Family Genes in Maize (Zea mays) and Functional Analysis of ZmFLZ25 in Plant Abscisic Acid Response.

FCS-like zinc finger family proteins (FLZs), a class of plant-specific scaffold of SnRK1 complex, are involved in the regulation of various aspects of plant growth and stress responses. Most information of FLZ family genes was obtained from the studies in Arabidopsis thaliana, whereas little is known about the potential functions of FLZs in crop plants. In this study, 37 maize FLZ (ZmFLZ) genes were identified to be asymmetrically distributed on 10 chromosomes and can be divided into three subfamilies. Protein interaction and subcellular localization assays demonstrated that eight typical ZmFLZs interacted and partially co-localized with ZmKIN10, the catalytic α-subunit of the SnRK1 complex in maize leaf mesophyll cells. Expression profile analysis revealed that several ZmFLZs were differentially expressed across various tissues and actively responded to diverse abiotic stresses. In addition, ectopic overexpression of ZmFLZ25 in Arabidopsis conferred hypersensitivity to exogenous abscisic acid (ABA) and triggered higher expression of ABA-induced genes, pointing to the positive regulatory role of ZmFLZ25 in plant ABA signaling, a scenario further evidenced by the interactions between ZmFLZ25 and ABA receptors. In summary, these data provide the most comprehensive information on FLZ family genes in maize, and shed light on the biological function of ZmFLZ25 in plant ABA signaling.

Differences in the gut microbiomes of dogs and wolves: roles of antibiotics and starch.

BACKGROUND: Dogs are domesticated wolves. Change of living environment, such as diet and veterinary care may affect the gut bacterial flora of dogs. The aim of this study was to assess the gut bacterial diversity and function in dogs compared with captive wolves. We surveyed the gut bacterial diversity of 27 domestic dogs, which were fed commercial dog food, and 31 wolves, which were fed uncooked meat, by 16S rRNA sequencing. In addition, we collected fecal samples from 5 dogs and 5 wolves for shotgun metagenomic sequencing to explore changes in the functions of their gut microbiome. RESULTS: Differences in the abundance of core bacterial genera were observed between dogs and wolves. Together with shotgun metagenomics, the gut microbiome of dogs was found to be enriched in bacteria resistant to clinical drugs (P < 0.001), while wolves were enriched in bacteria resistant to antibiotics used in livestock (P < 0.001). In addition, a higher abundance of putative α-amylase genes (P < 0.05; P < 0.01) was observed in the dog samples. CONCLUSIONS: Living environment of dogs and domestic wolves has led to increased numbers of bacteria with antibiotic resistance genes, with exposure to antibiotics through direct and indirect methods. In addition, the living environment of dogs has allowed the adaptation of their microbiota to a starch-rich diet. These observations align with a domestic lifestyle for domestic dogs and captive wolves, which might have consequences for public health.

Adaptive Evolution of Feline Coronavirus Genes Based on Selection Analysis.

PURPOSE: We investigated sequences of the feline coronaviruses (FCoV), which include feline enteric coronavirus (FECV) and feline infectious peritonitis virus (FIPV), from China and other countries to gain insight into the adaptive evolution of this virus. METHODS: Ascites samples from 31 cats with suspected FIP and feces samples from 8 healthy cats were screened for the presence of FCoV. Partial viral genome sequences, including parts of the nsp12-nsp14, S, N, and 7b genes, were obtained and aligned with additional sequences obtained from the GenBank database. Bayesian phylogenetic analysis was conducted, and the possibility of recombination within these sequences was assessed. Analysis of the levels of selection pressure experienced by these sequences was assessed using methods on both the PAML and Datamonkey platforms. RESULTS: Of the 31 cats investigated, two suspected FIP cats and one healthy cat tested positive for FCoV. Phylogenetic analysis showed that all of the sequences from mainland China cluster together with a few sequences from the Netherlands as a distinct clade when analyzed with FCoV sequences from other countries. Fewer than 3 recombination breakpoints were detected in the nsp12-nsp14, S, N, and 7b genes, suggesting that analyses for positive selection could be conducted. A total of 4, 12, 4, and 4 positively selected sites were detected in the nsp12-nsp14, S, N, and 7b genes, respectively, with the previously described site 245 of the S gene, which distinguishes FIPV from FECV, being a positive selection site. Conversely, 106, 168, 25, and 17 negative selection sites in the nsp12-14, S, N, and 7b genes, respectively, were identified. CONCLUSION: Our study provides evidence that the FCoV genes encoding replicative, entry, and virulence proteins potentially experienced adaptive evolution. A greater number of sites in each gene experienced negative rather than positive selection, which suggests that most of the protein sequence must be conservatively maintained for virus survival. A few of the sites showing evidence of positive selection might be associated with the more severe pathology of FIPV or help these viruses survive other harmful conditions.

HY5-HDA9 Module Transcriptionally Regulates Plant Autophagy in Response to Light-to-Dark Conversion and Nitrogen Starvation.

Light is arguably one of the most important environmental factors that determines virtually all aspects of plant growth and development, but the molecular link between light signaling and the autophagy pathway has not been elucidated in plants. In this study, we demonstrate that autophagy is activated during light-to-dark conversion though transcriptional upregulation of autophagy-related genes (ATGs). We showed that depletion of the ELONGATED HYPOCOTYL 5 (HY5), a key component of light signaling, leads to enhanced autophagy activity and resistance to extended darkness and nitrogen starvation treatments, contributing to higher expression of ATGs. HY5 interacts with and recruits HISTONE DEACETYLASE 9 (HDA9) to ATG5 and ATG8e loci to repress their expression by deacetylation of the Lys9 and Lys27 of histone 3. Furthermore, we found that both darkness and nitrogen depletion induce the degradation of HY5 via 26S proteasome and the concomitant disassociation of HDA9 from ATG5 and ATG8e loci, leading to their depression and thereby activated autophagy. Genetic analysis further confirmed that HY5 and HDA9 act synergistically and function upstream of the autophagy pathway. Collectively, our study unveils a previously unknown transcriptional and epigenetic network that regulates autophagy in response to light-to-dark conversion and nitrogen starvation in plants.