Chemical genetic screening identifies nalacin as an inhibitor of GH3 amido synthetase for auxin conjugation.

Auxin inactivation is critical for plant growth and development. To develop plant growth regulators functioning in auxin inactivation pathway, we performed a phenotype-based chemical screen in Arabidopsis and identified a chemical, nalacin, that partially mimicked the effects of auxin. Genetic, pharmacological, and biochemical approaches demonstrated that nalacin exerts its auxin-like activities by inhibiting indole-3-acetic acid (IAA) conjugation that is mediated by Gretchen Hagen 3 (GH3) acyl acid amido synthetases. The crystal structure of Arabidopsis GH3.6 in complex with D4 (a derivative of nalacin) together with docking simulation analysis revealed the molecular basis of the inhibition of group II GH3 by nalacin. Sequence alignment analysis indicated broad bioactivities of nalacin and D4 as inhibitors of GH3s in vascular plants, which were confirmed, at least, in tomato and rice. In summary, our work identifies nalacin as a potent inhibitor of IAA conjugation mediated by group II GH3 that plays versatile roles in hormone-regulated plant development and has potential applications in both basic research and agriculture.

Tuning d-orbitals to control spin-orbit coupling in terminated MXenes.

Theory and experiment have revealed that spin-orbit coupling (SOC) strongly depends on the relativistic effect in topological insulators (TIs), while the influence of orbitals is always ignored. Herein, we provide a direct way of controlling effective SOC with the help of orbital effects, reducing the dependence on elements. Taking 5d W2CO2 and 4d Mo2CO2 MXenes as a specific example, we predict that by decreasing the hybridization strength of W atoms with C or O atoms in 2D W2CO2, the nontrivial bandgaps at the Γ-point are directly enhanced. The weak hybridization of W atoms with ligand elements enhances the electron localization of degenerate d-orbitals of three groups under the triangular prism crystal field, inducing stronger on-site Coulomb repulsion that enhances orbital polarization as well as boosts the SOC effect. Meanwhile, similar results have also been observed in 4d Mo2CO2. This implies that the orbital effects are an efficient and straightforward way to control the nontrivial bandgap in 2D MXene TIs. Our work not only provides an alternative perspective on designing large nontrivial bandgaps but also brings a possibility to control the SOC effect for TI devices.

Risk of internal fixation treatment in intertrochanteric fracture based on different lateral femoral wall thickness: finite element analysis.

OBJECTIVE: The thickness of the lateral femoral wall, which is an important indicator for evaluating the stability and integrity of intertrochanteric fractures, has been widely studied in recent years. However, as a typical representative of internal fixation treatment, there are few reports on the biomechanical comparison between PFNA and DHS + CS. This study focused primarily on the biomechanical effects of different lateral femoral wall thicknesses on two types of internal fixation through finite element analysis. METHODS: We randomly recruited a healthy adult and collected his femoral CT data to establish a model of femoral intertrochanteric fracture with different lateral femoral wall thicknesses. Following PFNA and DHS + CS fixation, femoral models were simulated, and variations in stress and displacement of the internal fixation and femoral head were recorded under the same physiological load. RESULTS: First, finite element mechanical analysis revealed that the stress and displacement of the internal fixation and femoral head were lower in the femoral model after PFNA fixation than in the DHS + CS model. Second, as the outer wall thickness decreased, the stress and deformation endured by both types of internal fixation gradually increased. CONCLUSIONS: Finite element analysis determined that PFNA exhibits significantly better biomechanical stability than DHS + CS when subjected to varying lateral femoral wall thicknesses. Moreover, lateral femoral wall thickness substantially affects the stability of the two internal fixation biomechanical environments. When the thickness of the lateral femoral wall is too small, we do not recommend using extramedullary fixation because there is a significant risk of internal fixation fracture.

ETHYLENE INSENSITIVE 3 suppresses plant de novo root regeneration from leaf explants and mediates age-regulated regeneration decline.

Powerful regeneration ability enables plant survival when plants are wounded. For example, adventitious roots can regenerate from the cutting site in detached Arabidopsis thaliana leaf explants, even in the absence of any exogenous plant hormone treatment. This process is known as de novo root regeneration (DNRR). Although the developmental program underlying DNRR is known, the precise regulatory mechanisms underlying DNRR are not completely understood. Here, we show that ethylene treatment or genetic activation of transcription factor ETHYLENE INSENSITIVE 3 (EIN3) strongly suppresses DNRR rates, while a mutant lacking EIN3 and its homolog EIL1 (ein3 eil1) displays a higher DNRR capacity. Previous reports have shown that the sequential induction of WUSCHEL RELATED HOMEOBOX 11 (WOX11)/WOX12 and WOX5/WOX7 expression is required for the establishment of DNRR. We found that EIN3 directly targets WOX11 and WOX5 promoter regions to suppress their transcription. Furthermore, older plants show enhanced EIN3 activity, and repressed expression of WOX11 and WOX5 Taken together, these results illustrate that plant aging at least partially takes advantage of EIN3 as a negative regulator to suppress DNRR through inhibiting the activation of WOX genes.

Jasmonate: the Swiss army knife in the plant's pocket.

Jasmonate is a well-known defence hormone for plants, but it is also necessary for growth and development. Indeed, the identification of the COI1 receptor was based on the jasmonate-triggered response of root growth inhibition. In this special issue, a collection of review papers and two research papers discuss the current state of progress in this field, covering areas from seed germination and flowering to the Jasminum sambac genome.

Comparison of femoral neck system and three cannulated cancellous screws in the treatment of vertical femoral neck fractures: clinical observation and finite element analysis.

OBJECTIVE: The purpose of this study was to compare the biomechanical and clinical results of two surgical methods for the treatment of vertical femoral neck fractures: Femoral neck system (FNS) and traditional three cannulated cancellous screws (CCS). METHODS: First, we developed three different vertical femoral neck fracture models for the finite element analysis, with angles of 55°, 65°, and 75°, respectively. Two experimental groups were set up: the FNS group and the CCS group. Each fracture group was tested under axial loads of 2100 N to measure the femur's displacement, Von Mises stress (VMS), and its internal fixation components. Secondly, we retrospectively included the cases of vertical femoral neck fractures with FNS and CCS in our hospital from May 2019 to May 2021. In this study, we compared the duration of intraoperative fluoroscopy, operative time, hospital stay, fracture healing time, Hemoglobin loss, Harris score of hip joint function, and postoperative complications among patients undergoing hip joint replacement. RESULTS: In terms of finite element analysis, FNS has better anti-displacement stability than CCS at 55°and 65°, while FNS is greater than CCS in Von Mises stress. Clinically, we followed up on 87 patients for an average of 12 months. FNS was superior to traditional CCS in fracture healing time, operation time, fluoroscopy duration, fracture healing time, and Harris hip function score. CONCLUSION: FNS is superior to traditional CCS in biomechanical and clinical aspects of treating vertical femoral neck fractures. There is potential for FNS to become a new treatment option for vertical femoral neck fractures.

Prediction of hip joint function and analysis of risk factors for internal fixation failure after Femoral Neck System (FNS).

OBJECTIVE: Analysis of the risk factors affecting hip function and complications after femoral neck system (FNS) surgery for femoral neck fractures is of great significance for improving the procedure's efficacy. METHODS: The data of patients with femoral neck fractures who underwent FNS surgery in our hospital between October 2019 and October 2020 were retrospectively analyzed. Age, gender, time from injury to operation, fracture classification, operation time, fracture reduction, and postoperative weight-bearing time information were set as potential factors that may affect the results. Hip Harris scores were performed at 12 months postoperatively, and postoperative complication data (e.g., femoral head necrosis, nonunion, and femoral neck shortness) were collected. The risk factors affecting hip function and complications after FNS surgery were predicted using linear and logistic regression analyses. RESULTS: A total of 69 cases of femoral neck fracture were included, with an average age of 56.09 ± 11.50 years. The linear analysis demonstrated that the age and fracture type of the patients were the risk factors affecting the Harris score of the hip joint after FNS surgery. Older patients with displaced femoral neck fractures had an inferior postoperative hip function. In addition, fracture type, reduction of the femoral neck, and postoperative weight-bearing significantly impacted postoperative complications. Displaced fractures, negative fixation, and premature weight-bearing (< 6 weeks) were risk factors for postoperative complications. The Harris score of patients with a shortened femoral neck in the included cases was not significantly different from that of patients without shortening (P = 0.25). CONCLUSIONS: Advanced age and fracture type are important evaluation indicators of the Harris score after FNS internal fixation of femoral neck fractures in young patients. Fracture type, fracture reduction, and postoperative weight-bearing time are risk factors for complications after FNS.

Transporter NRT1.5/NPF7.3 suppresses primary root growth under low K+ stress by regulating the degradation of PIN-FORMED2.

BACKGROUND: The availability of potassium is one of the main environmental factors for modifying the plasticity of root architecture. Many potassium channels and transporters are involved in regulating primary root growth in response to low potassium stress. NRT1.5/NPF7.3 transporter is a NO3-/H+ and K+/H+ cotransporter, and participates in NO3- and K+ translocation from the roots to the shoots. However, the underlying mechanism of NRT1.5-regulated primary root growth under low potassium stress is unclear. RESULTS: We show that NRT1.5/NPF7.3 inhibited primary root growth under low potassium conditions by regulating the accumulation of PIN2 protein and auxin levels. Under low potassium conditions, the mutants nrt1.5 and lks2 exhibited longer primary roots, longer meristem regions and elongation zones of primary roots, and more cell activity in the meristem region compared to WT plants, revealing the involvement of NRT1.5 in LK (low potassium)-inhibition primary root growth. In addition, exogenous auxin (IAA), auxin analogue (NAA, 2.4-D) or auxin precursor (IBA) promoted the primary root growth of WT and the complementation line NRT1.5 COM plants. In addition, the application of NPA inhibited the primary root growth of the nrt1.5 and lks2 mutants. Auxin accumulation was higher in the root tip of nrt1.5 plants than in WT plants, indicating that NRT1.5 regulates root growth inhibition by regulating auxin distribution. Furthermore, PIN2 was degraded more quickly in nrt1.5 plants under LK stress. CONCLUSIONS: Our findings reveal that NRT1.5 inhibits primary root growth by modulating the auxin level in the root tip via the degradation of PIN2.

The AP2 transcription factors TOE1/TOE2 convey Arabidopsis age information to ethylene signaling in plant de novo root regeneration.

MAIN CONCLUSION: We reveal that transcription factors TOE1 and TOE2 directly inhibit the transcription of EIN3. Ethylene triggers leaf abscission and senescence during plant aging. Previous studies have shown that the transcription of ETHYLENE INSENSITIVE 3 (EIN3), which encodes a key transcription factor in ethylene signaling, is gradually upregulated during plant aging. However, it is still unknown how plants transmit their age information to achieve transcriptional control of EIN3. Here, we report that the EAR-like motif-containing transcription factors TARGET OF EAT 1 (TOE1) and its homolog TOE2 directly associated with the EIN3 promoter. The transcription of EIN3 is further enhanced in mutants of toe1 toe2 during plant aging. TOE1/TOE2 are tightly controlled by canonical microRNA 172 (miR172)-mediated plant aging signaling, which result in a decline in TOE1/TOE2 expression during aging. These results illustrate that during plant aging, the reduced expressions of TOE1/TOE2 trigger an upregulation of EIN3. Next, we took advantage of EIN3-regulated de novo root regeneration (DNRR) as an age-controlled phenotype to dissect the biological function of this regulatory circuit. The DNRR rates in toe1 toe2 are more severely decreased with plant aging; however, the simultaneous loss of ein3 and eil1 (toe1 toe2 ein3 eil1 quadruple mutants) almost completely rescued the DNRR defects. Taken together, our findings show that the plant age-regulated TOE transcription factors precisely integrate plant age information and developmental programs through direct protein-DNA interactions.

Effects of working pressure on the material and defect properties of Sb2S3 thin-film solar cells achieved by the VTD method.

Antimony sulfide (Sb2S3), an emerging material for photovoltaic devices, has drawn growing research interest due to its inexpensive and high-throughput device production. In this study, the material and defect properties of Sb2S3 thin films prepared by the vapor transport deposition (VTD) method at different working pressures were studied. Solar cells based on a structure of glass/ITO/CdS/Sb2S3/Au were fabricated. The working pressure showed a significant effect on the device's performance. The current density versus voltage measurement and scanning electron microscopy analysis outcome were utilized to investigate the photovoltaic and microstructural properties in the samples. The compositional analysis by energy dispersive X-ray spectroscopy measurement confirmed the Sb/S ratio as 2:2.8 for the thin films. The identification and characterization of the defects present in Sb2S3 thin films were performed via admittance measurements. Compared to the defect density, the defect energy level was found to inherit a more important role in the device's performance. The best solar cell performance with better crystal quality, lower defect density, and longer capture lifetime was achieved under the substrate working pressure of 2 Pa. The highest efficiency was found to be 0.86% with Voc=0.55V, Jsc=5.07mA/cm2.

A novel model of traumatic femoral head necrosis in rats developed by microsurgical technique.

BACKGROUND: Clinical angiography and vascular microperfusion confirmed that the femoral head retains blood supply after a collum femur fracture. However, no animal model accurately mimics this clinical situation. This study was performed to establish a rat model with retained viability of the femoral head and partial vasculature deprivation-induced traumatic caput femoris necrosis by surgery. METHODS: Thirty rats were randomly divided into three groups (n = 10 per group): normal group, sham-operated group (Control), and ischemic osteonecrosis group. The femoral head of the normal group of rats underwent a gross anatomy study and microangiography to identify femoral head blood supply. Microsurgical techniques were used to cauterize the anterior-superior retinacular vessels to induce osteonecrosis. Hematoxylin and Eosin (H&E) staining were used for femoral head histologic assessment. Morphologic assessments of the deformity in and trabecular bone parameters of the femoral head epiphysis were performed using micro-CT. RESULTS: The blood supply of the femoral head in rats primarily came from the anterior-superior, inferior, and posterior retinacular arteries. However, anterior-superior retinacular vasculature deprivation alone was sufficient in inducing femoral head osteonecrosis. H&E showed bone cell loss in nuclear staining, disorganized marrow, and trabecular structure. The bone volume (BV) decreased by 13% and 22% in the ischemic group after 5 and 10 weeks, respectively. The mean trabecular thickness (Tb.Th) decreased from 0.09 to 0.06 mm after 10 weeks. The trabecular spacing (Tb.Sp) increased from 0.03 to 0.05 mm after 5 weeks, and the epiphyseal height-to-diameter (H/D) ratio decreased. CONCLUSIONS: We developed an original and highly selective rat model that embodied femoral head traumatic osteonecrosis induced by surgical anterior-superior retinacular vasculature deprivation.

Plant responses to high temperature: a view from pre-mRNA alternative splicing.

KEY MESSAGE: This review focused on the recent breakthroughs in plant high temperature responses from an alternative splicing angle. With the inevitable global warming, high temperature triggers plants to change their growth and developmental programs for adapting temperature increase. In the past decades, the signaling mechanisms from plant thermo-sensing to downstream transcriptional cascades have been extensively studied. Plenty of elegant review papers have summarized these breakthroughs from signal transduction to cross-talk within plant hormones and environmental cues. Precursor messenger RNA (pre-mRNA) splicing enables plants to produce a series of functional un-related proteins and thus enhances the regulation flexibility. Plants take advantage of this strategy to modulate their proteome diversity under high ambient temperature and elicit developmental plasticity. In this review, we particularly focus on pre-mRNA splicing regulation underlying plant high temperature responses, and will shed new light on the understanding of post-transcriptional regulation on plant growth and development.

The Molecular Basis of Age-Modulated Plant De Novo Root Regeneration Decline in Arabidopsis thaliana.

Plants possess a regeneration capacity that enables them to survive after wounding. For example, detached Arabidopsis thaliana leaves are able to form adventitious roots from their cutting sites even in the absence of exogenous hormone supplements, as process termed de novo root regeneration (DNRR). Wounding rapidly induces auxin biosynthesis at the cutting sites and then elicits a signaling cascade to promote cell fate transitions and finally generate the adventitious roots. However, rooting rates in older plants are much lower than in younger leaf explants. In this review, we highlight the recent breakthroughs in the understanding of DNRR decay in older plants from at least two independent signaling routes: (i) via the accumulation of EIN3 protein in older plants, which directly suppresses expression of WUSCHEL RELATED HOMEOBOX (WOX) genes to inhibit rooting; (ii) the miR156-SPLs-AP2/ERFs pathway, which modulates root regeneration by reducing auxin biosynthesis.

The origin of SPA reveals the divergence and convergence of light signaling in Archaeplastida.

Plants have evolved various photoreceptors to adapt to changing light environments, and photoreceptors can inactivate the large CONSTITUTIVE PHOTOMORPHOGENIC/DE-ETIOLATED/FUSCA (COP/DET/FUS) protein complex to release their repression of photoresponsive transcription factors. Here, we tracked the origin and evolution of COP/DET/FUS in Archaeplastida and found that most components of COP/DET/FUS were highly conserved. Intriguingly, the COP1-SUPPRESSOR OF PHYA-105 (SPA) protein originated in Chlorophyta but subsequently underwent a distinct evolutionary history in Viridiplantae. SPA experienced duplication events in the ancestors of specific clades after the colonization of land by plants and was divided into two clades (clades A and B) within euphyllophytes (ferns and seed plants). Our phylogenetic and experimental evidences support a new evolutionary model to clarify the divergence and convergence of light signaling during plant evolution.

Caregiver burden and parenting stress among left-behind elderly individuals in rural China: a cross-sectional study.

BACKGROUND: One public health problem that cannot be ignored is the mental health of left-behind elderly individuals in rural areas. However, the burden of care and parenting stress among left-behind elderly individuals has never been analyzed. The purpose of this study was to explore the level of caregiver burden and parenting stress and their relationship among left-behind elderly individuals. METHODS: A total of 261 left-behind elderly people responded to the study. The 22-item Zarit Burden Interview and the 36-item Parenting Stress Index-Short Form were used. RESULTS: We sent out 300 questionnaires in total. The effective rate was 87% (n = 261). Among the left-behind elderly individuals, most respondents were female (n = 171; 65.5%). The results showed that older age (OR:3.04; 95%CI: 1.307-7.048), an annual income of ¥5000-¥9900 (OR:3.25; 95%CI: 1.192-8.852) and higher parenting stress (OR:1.17; 95%CI: 1.103-1.242) were the risk factors related to higher caregiver burden in the left-behind elderly individuals. The influencing factor for lower caregiver burden in the left-behind elderly was gender (being male) (OR:0.08; 95%CI:0.036-0.178). Age (r = - 0.789; P < 0.001) and gender (r = 0.325; P < 0.001) were significant positively correlated with parenting stress, and annual income (r = - 0.717; P < 0.001) was negatively correlated with parenting stress. CONCLUSION: Parenting stress is a risk factor affecting caregiver burden of left-behind elderly individuals. Healthcare professionals should pay close attention to the caregiver burden and parenting stress of left-behind elderly individuals, especially those who are older, female and have lower income.

Dendrobium officinale flos increases neurotrophic factor expression in the hippocampus of chronic unpredictable mild stress-exposed mice and in astrocyte primary culture and potentiates NGF-induced neuronal differentiation in PC12 cells.

Dendrobium officinale flos (DOF) is the flower of Dendrobium officinale Kimura et Migo, which is usually regarded as a by-product of Dendrobii Offcinalis Caulis. Based on its use as an alternative medicine, we evaluated the antidepressant-like effect of DOF extracts on chronic, unpredictable, mild stress-induced, depression-like behaviour in mice and tested the effects of DOF on the regulation of neurotrophic factors in mouse astrocyte primary cultures and PC12 cell lines. Oral treatment with DOF ethanol extract (DOF-E) could alleviate depression-like behaviours in stress-exposed mice, as evidenced by increased sucrose consumption and decreased immobile time in a forced swim test. In the hippocampus, DOF extracts increased the expression of NGF and BDNF, both at the transcriptional and protein levels. In astrocytes, DOF-E increased the expression of NGF and BDNF via a cAMP-dependent mechanism and regulated plasminogen and matrix metallopeptidase 9 (MMP-9), which are related to the metabolic regulation of neurotrophic factors. In PC12 cells, DOF-E induced the expression of neurofilaments and potentiated the induction of neurite outgrowth upon treatment with a low dose of NGF. Based on these findings, DOF might be used as a supplement for antidepressant therapy in patients with depression.

PIF4 and PIF4-Interacting Proteins: At the Nexus of Plant Light, Temperature and Hormone Signal Integrations.

Basic helix-loop-helix (bHLH) family transcription factor PHYTOCHROME INTERACTING FACTOR 4 (PIF4) is necessary for plant adaption to light or high ambient temperature. PIF4 directly associates with plenty of its target genes and modulates the global transcriptome to induce or reduce gene expression levels. However, PIF4 activity is tightly controlled by its interacting proteins. Until now, twenty-five individual proteins have been reported to physically interact with PIF4. These PIF4-interacting proteins act together with PIF4 and form a unique nexus for plant adaption to light or temperature change. In this review, we will discuss the different categories of PIF4-interacting proteins, including photoreceptors, circadian clock regulators, hormone signaling components, and transcription factors. These distinct PIF4-interacting proteins either integrate light and/or temperature cues with endogenous hormone signaling, or control PIF4 abundances and transcriptional activities. Taken together, PIF4 and PIF4-interacting proteins play major roles for exogenous and endogenous signal integrations, and therefore establish a robust network for plants to cope with their surrounding environmental alterations.

CIRCADIAN CLOCK ASSOCIATED 1 gates morning phased auxin response in Arabidopsis thaliana.

Circadian clock controls plant behaviors to anticipate day-night switch and keeps plant fitness. Here, we reported that plant response to auxin is also strictly governed by clock. The amplitude of auxin-responsive gene expressions gradually declined from morning to the dusk, and then enhanced from dusk to dawn. Plants with defects in both CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and its closest homologue LATE ELONGATED HYPOCOTYL (LHY) (cca1 lhy) showed comparable responses to auxin at different time points in consecutive days, suggesting that CCA1 and LHY were required for gating auxin responses. Moreover, CCA1/LHY physically interacted with the core transcriptional repressors (Aux/IAA proteins), which might further modulate plant sensitivity to auxin. Taken together, we demonstrate that the central morning phased circadian oscillator CCA1 plays a pivotal role in gating auxin response.

microRNA-199a counteracts glucocorticoid inhibition of bone marrow mesenchymal stem cell osteogenic differentiation through regulation of Klotho expression in vitro.

Osteogenic differentiation (OD) of bone marrow mesenchymal stem cells (BMSCs) is critically important for mitigation of osteoporosis. Glucocorticoids (GCs) are extensively used for treating chronic inflammation, although long-term exposure to GCs is capable of triggering osteoporosis. microRNAs (miRNAs) have been reported to play a critical role in bone diseases. In the present study, we treated BMSCs with dexamethasone (DEX) during OD to stimulate GC-mediated osteoporosis. Microarray and quantitative polymerase chain reaction (Q-PCR) assays demonstrated that miR-199a was upregulated during OD of BMSCs, while DEX treatment caused a significant reduction in miR-199a. Alkaline phosphatase (ALP) activity, Alizarin red (AR) staining, and Q-PCR were applied to assess the role of miRNA-199a overexpression in DEX-triggered OD inhibition. miR-199a was able to rescue OD and ALP activity, which were inhibited by DEX. Additionally, we observed that ALP, BMP2, COL1A1, and Runx2 were increased after transfection of miRNA-199a mimics. Furthermore, we confirmed that miRNA-199a facilitates OD of BMSCs through direct inhibition of Klotho protein and messenger RNA expression affecting the downstream fibroblast growth factor receptor 1/extracellular-signal-regulated kinase and Janus kinase 1/signal transducer and activator of transcription 1 pathways. This study indicates that miR-199a plays a critical role in preventing GC-mediated osteoblast differentiation and may function as a promising miRNA biomarker for osteoporosis.

Enhancing performance of perovskite solar cells with efficiency exceeding 21% via a graded-index mesoporous aluminum oxide antireflection coating.

Antireflection (AR) film is a widely used technology to enhance the performance of photovoltaic devices that require transparent electrodes in the photovoltaic industry. At present, several AR films including monolayer MgF2 or multilayered composite films, textured polydimethylsiloxane (PDMS) and porous SiO2 have been successfully applied due to their excellent properties. Nevertheless, all of the above-mentioned AR films have some minor drawbacks to overcome, for instance, the cost or thermal durability. Herein, we report a cost-effective and low-temperature method to fabricate a mesoporous aluminum oxide (meso-Al2O3) layer as the AR coating with high thermal durability, which will meet the fabrication condition of various photovoltaic devices. Briefly, the process begins at magnetron sputtering a compact Al2O3 film, which shows no AR effect, followed by a hot water treatment at 80 °C to turn the compact film into a mesoporous film with graded-index and AR effect. The application of meso-Al2O3 AR film enhances the maximum transmittance of our laboratory-used fluorine-doped tin oxide (FTO) from 84% to 89%, which is in good agreement with our theoretical simulation named graded-index approximation. Taking perovskite solar cells (PSCs) as an example, planar PSCs with meso-Al2O3 AR film deliver excellent photon conversion efficiency of 21.5%, which is higher than that of cells without meso-Al2O3 AR film (20.9%).