Buried interface molecular hybrid for inverted perovskite solar cells.

Perovskite solar cells (PSCs) with an "inverted" architecture are a key pathway for commercializing this emerging photovoltaic technology due to the better power conversion efficiency (PCE) and operational stability as compared to the "normal" device structure. Specifically, PCEs of the inverted PSCs have exceeded 25% owing to the development of improved self-assembled molecules (SAMs)1-5 and passivation strategies6-8. Nevertheless, poor wettability and agglomerations of SAMs9-12 will cause interfacial losses, impeding further improvement in PCE and stability. Herein, we report on molecular hybrid at the buried interface in inverted PSCs by co-assembling a multiple carboxylic acid functionalized aromatic compound of 4,4',4''-nitrilotribenzoicacid (NA) with a popular SAM of [4-(3,6-dime-thyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz) to improve the heterojunction interface. The molecular hybrid of Me-4PACz with NA could substantially improve the interfacial characteristics. The resulting inverted PSCs demonstrated a record-certified steady-state efficiency of 26.54%. Crucially, this strategy aligns seamlessly with large-scale manufacturing, achieving the highest certified PCE for inverted mini-modules at 22.74% (aperture area: 11.1 cm2). Our device also maintained 96.1% of its initial PCE after more than 2,400 hours of 1-sun operation in ambient air.

Hypoxia Reversion by Low-Immunogenic Ultra-Acid-Sensitive Comicelles of Protein-Polymer Conjugates Sensitizes Tumors to Photodynamic Therapy.

Hypoxia is characteristic of the tumor microenvironment, which is correlated with resistance to photodynamic therapy (PDT), radiotherapy, chemotherapy, and immunotherapy. Catalase is potentially useful to catalyze the conversion of endogenous H2O2 to O2 for hypoxia reversion. However, the efficient delivery of catalase into the hypoxia regions of tumors is a huge challenge. Here, we report the self-assembly of ultra-acid-sensitive polymer conjugates of catalase and albumin into nanomicelles that are responsive to the acidic tumor microenvironment. The immunogenicity of catalase is mitigated by the presence of albumin, which reduces the cross-linking of catalase with B cell receptors, resulting in improved pharmacokinetics. The ultra acid sensitivity of the nanomicelles makes it possible to efficiently escape the lysosomal degradation after endocytosis and permeate into the interior of tumors to reverse hypoxia in vitro and in vivo. In mice bearing triple-negative breast cancer, the nanomicelles loaded with a photosensitizer effectively accumulate and penetrate into the whole tumors to generate a sufficient amount of O2 to reverse hypoxia, leading to enhanced efficacy of PDT without detectable side effects. These findings provide a general strategy of self-assembly to design low-immunogenic ultra-acid-sensitive comicelles of protein-polymer conjugates to reverse tumor hypoxia, which sensitizes tumors to PDT.

Novel superhard semiconducting structures of C8B2N2 predicted using the first-principles approach.

Using first-principles calculations, we predicted three novel superhard semiconducting structures of C8B2N2 with a space group of P3m1. We investigated their mechanical properties and electronic structures up to 100 GPa. These three structures were successfully derived by substituting carbon (C) atoms with isoelectronic boron (B) and nitrogen (N) atoms in the P3m1 phase, which is the most stable structure of BCN and exhibits exceptional mechanical properties. Our results indicated that these structures had superior energy over previously reported t-C8B2N2, achieved by replacing C atoms in the diamond supercell with B and N atoms. To ensure their stable existence, we thoroughly examined their mechanical and dynamical stabilities, and we found that their hardness values reached 82.4, 83.1, and 82.0 GPa, which were considerably higher than that of t-C8B2N2 and even surpassing the hardness of c-BN. Calculations of the electron localization function revealed that the stronger carbon-carbon covalent bonds made them much harder than t-C8B2N2. Additionally, our further calculations of band structures revealed that these materials had indirect bandgaps of 4.164, 4.692, and 3.582 eV. These findings suggest that these materials have the potential to be used as superhard semiconductors, potentially surpassing conventional superhard materials.

Hypoxia-Triggered Bioreduction of Poly(N-oxide)-Drug Conjugates Enhances Tumor Penetration and Antitumor Efficacy.

PEGylation prolongs the blood circulation time of drugs; however, it simultaneously reduces the tumor penetration of drugs due to the nonfouling function and bulky hydrodynamic volume of PEG, leading to unsatisfactory outcomes in the treatment of solid tumors. Herein, we report the in situ growth of a bioreducible polymer of poly(N-oxide) from an important protein drug of interferon alpha (IFN) to generate site-specific IFN-poly(N-oxide) conjugates with higher bioactivity than a clinically used PEGylated IFN of PEGASYS. An IFN-poly(N-oxide) conjugate is screened out to have a circulating half-life as long as 51 h, which is similar to that of PEGASYS but 96-fold greater than that of IFN. However, the conjugate greatly outperforms PEGASYS and IFN in tumor penetration and antitumor efficacy in mice bearing melanoma. This enhanced tumor penetration is ascribed to the adsorption-mediated transcytosis of the conjugate whose poly(N-oxide) is biologically reduced into poly(tertiary amine), under hypoxia, which can be further protonated in the acidic tumor microenvironment. These novel findings demonstrate that poly(N-oxide)s are not only long-circulating but also bioreducible under hypoxia and are of great promise as next-generation carriers to deliver drugs into the interior of solid tumors to enhance their antitumor efficacy.

Age, creatinine, and ejection fraction (ACEF) score as predictive values for late non-valvular atrial fibrillation recurrence after radiofrequency ablation.

The clinical risk factors associated with late recurrence in patients with non-valvular atrial fibrillation (AF) (NVAF) undergoing radiofrequency catheter ablation (RFCA) remain unknown. Furthermore, the current prognostic risk score system is commonly used in such patients as a noninvasive method to assess late AF recurrence. According to recent research, the Age, creatinine, and ejection fraction (ACEF) score is a useful risk score for cardiovascular morbidity and mortality. As a result, we hypothesized that pre-ablation ACEF score could be used to assess late recurrence in patients with NVAF. We included 325 NVAF patients undergoing RFCA. During a median follow-up period of 12 months, patients with late AF recurrence had higher ACEF scores (P < .001). The pre-ablation ACEF score was a risk factor for late AF recurrence after RFCA (P = .027). The ACEF score was a predictor of late AF recurrence after RFCA, with an AUC of 0.624 (P = .001). Moreover, the AUC of left atrial diameter (LAD) was 0.7 (P < .001), which was higher than the ACEF score, but no significant difference was found (P = .104). The ACEF score was positively correlated with LAD, advanced age, and B-type natriuretic peptide. In patients with NVAF, the pre-ablation ACEF score is a valuable risk score for assessing late AF recurrence after RFCA, as with LAD.

Highly efficient organic photovoltaics with enhanced stability through the formation of doping-induced stable interfaces.

Flexible organic photovoltaics (OPVs) are promising power sources for wearable electronics. However, it is challenging to simultaneously achieve high efficiency as well as good stability under various stresses. Herein, we demonstrate the fabrication of highly efficient (efficiency, 13.2%) and stable OPVs based on nonfullerene blends by a single-step postannealing treatment. The device performance decreases dramatically after annealing at 90 °C and is fully recovered after annealing at 150 °C. Glass-encapsulated annealed OPVs show good environmental stability with 4.8% loss in efficiency after 4,736 h and an estimated T 80 lifetime (80% of the initial power conversion efficiency) of over 20,750 h in the dark under ambient condition and T 80 lifetime of 1,050 h at 85 °C and 30% relative humidity. This environmental stability is enabled by the synergetic effect of the stable morphology of donor/acceptor blends and thermally stabilized interfaces due to doping. Furthermore, the high efficiency and good stability are almost 100% retained in ultraflexible OPVs and minimodules which are mechanically robust and have long-term operation capability and thus are promising for future self-powered and wearable electronics.

The Alpha Subunit of Mitochondrial Processing Peptidase Participated in Fertility Restoration in Honglian-CMS Rice.

The cytoplasmic male sterility (CMS) and nuclear-controlled fertility restoration system is a favorable tool for the utilization of heterosis in plant hybrid breeding. Many restorer-of-fertility (Rf) genes have been characterized in various species over the decades, but more detailed work is needed to investigate the fertility restoration mechanism. Here, we identified an alpha subunit of mitochondrial processing peptidase (MPPA) that is involved in the fertility restoration process in Honglian-CMS rice. MPPA is a mitochondrial localized protein and interacted with the RF6 protein encoded by the Rf6. MPPA indirectly interacted with hexokinase 6, namely another partner of RF6, to form a protein complex with the same molecular weight as the mitochondrial F1F0-ATP synthase in processing the CMS transcript. Loss-of-function of MPPA resulted in a defect in pollen fertility, the mppa+/- heterozygotes showed semi-sterility phenotype and the accumulation of CMS-associated protein ORFH79, showing restrained processing of the CMS-associated atp6-OrfH79 in the mutant plant. Taken together, these results threw new light on the process of fertility restoration by investigating the RF6 fertility restoration complex. They also reveal the connections between signal peptide cleavage and the fertility restoration process in Honglian-CMS rice.

The metabolomic landscape of rice heterosis highlights pathway biomarkers for predicting complex phenotypes.

Understanding the molecular mechanisms underlying complex phenotypes requires systematic analyses of complicated metabolic networks and contributes to improvements in the breeding efficiency of staple cereal crops and diagnostic accuracy for human diseases. Here, we selected rice (Oryza sativa) heterosis as a complex phenotype and investigated the mechanisms of both vegetative and reproductive traits using an untargeted metabolomics strategy. Heterosis-associated analytes were identified, and the overlapping analytes were shown to underlie the association patterns for six agronomic traits. The heterosis-associated analytes of four yield components and plant height collectively contributed to yield heterosis, and the degree of contribution differed among the five traits. We performed dysregulated network analyses of the high- and low-better parent heterosis hybrids and found multiple types of metabolic pathways involved in heterosis. The metabolite levels of the significantly enriched pathways (especially those from amino acid and carbohydrate metabolism) were predictive of yield heterosis (area under the curve = 0.907 with 10 features), and the predictability of these pathway biomarkers was validated with hybrids across environments and populations. Our findings elucidate the metabolomic landscape of rice heterosis and highlight the potential application of pathway biomarkers in achieving accurate predictions of complex phenotypes.

Adjustment of the GRACE score by the triglyceride glucose index improves the prediction of clinical outcomes in patients with acute coronary syndrome undergoing percutaneous coronary intervention.

BACKGROUND: The Global Registry of Acute Coronary Events (GRACE) score derived from clinical parameters at the time of hospital discharge is a powerful predictor of long-term mortality and reinfarction after acute coronary syndrome (ACS). The triglyceride glucose (TyG) index, which is a simple and reliable surrogate marker of insulin resistance, has been demonstrated to be an independent predictor of long-term adverse major adverse cardiac events, irrespective of diabetes mellitus. We investigate whether the addition of the TyG index improves the predictive ability of the GRACE score after percutaneous coronary intervention (PCI) in ACS patients regardless of diabetes mellitus. METHOD: A retrospective cohort of 986 ACS patients undergoing PCI was enrolled in the present analyses. The GRACE score for discharge to 6 months and the TyG index were calculated. The primary endpoint was the composite of MACEs, including all-cause death and nonfatal myocardial infarction. Patients were stratified according to the primary endpoint and the tertiles of the TyG index. Cumulative curves were calculated using the Kaplan-Meier method. Multivariate Cox regression was adopted to identify predictors of MACEs. The predictive value of the GRACE score alone and combined with the TyG index or fasting blood glucose (FBG) was estimated by the area under the receiver­operating characteristic curve, likelihood ratio test, Akaike's information criteria, continuous net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Internal validation was assessed using the means of bootstrap method with 1000 bootstrapped samples. RESULTS: During a median follow-up of 30.72 months ((interquartile range, 26.13 to 35.07 months), 90 patients developed MACEs, more frequently in the patients with a higher TyG index. Multivariate Cox hazards regression analysis found that the TyG index, but not FBG was an independent predictor of MACEs (hazard ratio 1.6542; 95% CI 1.1555-2.3681; P = 0.006) in all types of ACS regardless of diabetes mellitus when included in the same model as GRACE score. Furthermore, Kaplan-Meier analysis revealed that the incidence of the primary endpoint rose with increasing TyG index tertiles (log-rank, P < 0.01). Adjustment the GRACE score by the TyG index improved the predictive ability for MACEs (increase in C-statistic value from 0.735 to 0.744; NRI, 0.282, 95% CI 0.028-0.426, P = 0.02; IDI, 0.019, 95% CI 0.004-0.046, P = 0.01). Likelihood ratio test showed that the TyG index significantly improved the prognostic ability of the GRACE score (χ2 = 12.37, 1 df; P < 0.001). The results remained consistent when the models were confirmed by internal bootstrap validation method. CONCLUSION: The TyG index, but not FBG is an independent predictor of long-term MACEs after PCI in all types of ACS patients regardless of diabetes mellitus after adjusting for the GRACE score, and improves the ability of the GRACE score to stratify risk and predict prognosis of ACS patients undergoing PCI.

A microenvironment-responsive FePt probes for imaging-guided Fenton-enhanced radiotherapy of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) continues to be one of the most fatal malignancies with increasing morbidity, and potent therapeutics are urgently required given its insensitivity to traditional treatments. Here, we have developed a microenvironment-responsive FePt probes for the highly efficient Fenton-enhanced radiotherapy (FERT) of HCC. The selective release of Fe2+ in the acidic tumor microenvironment, but not in normal tissue, together with enhanced levels of hydrogen peroxide produced through the Pt radiosensitization effect, facilitates the generation of an enormous amount of hydroxyl radicals through the Fenton reaction, thereby extending the radiotherapeutic cascade and realizing a powerful therapeutic efficacy for HCC. Moreover, the "burst" release of Fe2+ contributes to the T2-to-T1 magnetic resonance imaging (MRI) switching effect, which informs the release of Fe2+, making imaging-guided cancer therapy feasible. This work not only breaks the bottleneck of traditional radiotherapy for HCC while minimally affecting normal tissues, but also provides a new strategy for FERT imaging guidance.

Genome-Wide Comprehensive Analysis of the Nitrogen Metabolism Toolbox Reveals Its Evolution and Abiotic Stress Responsiveness in Rice (Oryza sativa L.).

Nitrogen metabolism (NM) plays an essential role in response to abiotic stresses for plants. Enzyme activities have been extensively studied for nitrogen metabolism-associated pathways, but the knowledge of nitrogen metabolism-associated genes involved in stress response is still limited, especially for rice. In this study, we performed the genome-wide characterization of the genes putatively involved in nitrogen metabolism. A total of 1110 potential genes were obtained to be involved in nitrogen metabolism from eight species (Arabidopsis thaliana (L.) Heynh., Glycine max (L.) Merr., Brassica napus L., Triticum aestivum L., Sorghum bicolor L., Zea mays L., Oryza sativa L. and Amborella trichopoda Baill.), especially 104 genes in rice. The comparative phylogenetic analysis of the superfamily revealed the complicated divergence of different NM genes. The expression analysis among different tissues in rice indicates the NM genes showed diverse functions in the pathway of nitrogen absorption and assimilation. Distinct expression patterns of NM genes were observed in rice under drought stress, heat stress, and salt stress, indicating that the NM genes play a curial role in response to abiotic stress. Most NM genes showed a down-regulated pattern under heat stress, while complicated expression patterns were observed for different genes under salt stress and drought stress. The function of four representative NM genes (OsGS2, OsGLU, OsGDH2, and OsAMT1;1) was further validated by using qRT-PCR analysis to confirm their responses to these abiotic stresses. Based on the predicted transcription factor binding sites (TFBSs), we built a co-expression regulatory network containing transcription factors (TFs) and NM genes, of which the constructed ERF and Dof genes may act as the core genes to respond to abiotic stresses. This study provides novel sights to the interaction between nitrogen metabolism and the response to abiotic stresses.

OsGRP3 Enhances Drought Resistance by Altering Phenylpropanoid Biosynthesis Pathway in Rice (Oryza sativa L.).

As a sessile organism, rice often faces various kinds of abiotic stresses, such as drought stress. Drought stress seriously harms plant growth and damages crop yield every year. Therefore, it is urgent to elucidate the mechanisms of drought resistance in rice. In this study, we identified a glycine-rich RNA-binding protein, OsGRP3, in rice. Evolutionary analysis showed that it was closely related to OsGR-RBP4, which was involved in various abiotic stresses. The expression of OsGRP3 was shown to be induced by several abiotic stress treatments and phytohormone treatments. Then, the drought tolerance tests of transgenic plants confirmed that OsGRP3 enhanced drought resistance in rice. Meanwhile, the yeast two-hybrid assay, bimolecular luminescence complementation assay and bimolecular fluorescence complementation assay demonstrated that OsGRP3 bound with itself may affect the RNA chaperone function. Subsequently, the RNA-seq analysis, physiological experiments and histochemical staining showed that OsGRP3 influenced the phenylpropanoid biosynthesis pathway and further modulated lignin accumulation. Herein, our findings suggested that OsGRP3 enhanced drought resistance in rice by altering the phenylpropanoid biosynthesis pathway and further increasing lignin accumulation.

Crystal structures of rice hexokinase 6 with a series of substrates shed light on its enzymatic mechanism.

Hexokinases (HXKs) have determined to be multifaceted proteins, and they are the only ones able to phosphorylate glucose in plants. However, the binding mode for ATP to plant HXKs remains unclear. Here, we report the crystal structures of rice hexokinase 6 (OsHXK6) in four different forms: (i) apo-form, (ii) binary complex with D-Glc, (iii) quaternary complex with ADP, PO4 and Mg2+, and (iv) pentanary complex with D-Glc, ADP, PO4, and Mg2+. The apo form is in the open state conformation, and the three others are in the closed state, indicating that glucose and ADP-PO4 binding induces a large conformational change by domain rearrangement. The quaternary complex is a novel intermediate during the catalytic reaction we trapped for the first time, which provides a new evidence for the enzymatic mechanism of HXKs. In addition, the latter two complexes reveal the binding mode for ADP-PO4 to plant HXKs, which provide the structural explanation for the dual-function of OsHXK6. In addition, we identified that residues Gly112, Thr261, Gly262, and Gly450 are essential to the binding between ADP-PO4 and OsHXK6 by a series of single mutations and enzymatic assays. Our study provide structural basis for the other functional studies of OsHXK6 in rice.

A metabolome-based core hybridisation strategy for the prediction of rice grain weight across environments.

Marker-based prediction holds great promise for improving current plant and animal breeding efficiencies. However, the predictabilities of complex traits are always severely affected by negative factors, including distant relatedness, environmental discrepancies, unknown population structures, and indeterminate numbers of predictive variables. In this study, we utilised two independent F1 hybrid populations in the years 2012 and 2015 to predict rice thousand grain weight (TGW) using parental untargeted metabolite profiles with a partial least squares regression method. A stable predictive model for TGW was built based on hybrids from the population in 2012 (r = 0.75) but failed to properly predict TGW for hybrids from the population in 2015 (r = 0.27). After integrating hybrids from both populations into the training set, the TGW of hybrids could be predicted but was largely dependent on population structures. Then, core hybrids from each population were determined by principal component analysis and the TGW of hybrids in both environments were successfully predicted (r > 0.60). Moreover, adjusting the population structures and numbers of predictive analytes increased TGW predictability for hybrids in 2015 (r = 0.72). Our study demonstrates that the TGW of F1 hybrids across environments can be accurately predicted based on parental untargeted metabolite profiles with a core hybridisation strategy in rice. Metabolic biomarkers identified from early developmental stage tissues, which are grown under experimental conditions, may represent a workable approach towards the robust prediction of major agronomic traits for climate-adaptive varieties.

An easily-performed high-throughput method for plant genomic DNA extraction.

Genomic DNA isolation is a crucial technique for researchers studying plant molecular biology. A current widely-used protocol for DNA extraction needs a pestle and mortal for each sample and consumes a large amount of liquid nitrogen in grinding the samples. Most high-throughput methods depend on expensive machines for tissue homogenization. Here we developed a CTAB-based DNA extraction method using 2.0 mL microcentrifuge tubes for sample processing. This protocol has the advantages that it is suitable for a variety of plants, easily-performed without special equipment, and high-throughput; it effectively avoids sample cross-contamination, and is inexpensive, rapid and safe.

High Efficiency Non-fullerene Organic Tandem Photovoltaics Based on Ternary Blend Subcells.

The application of tandem structure that integrates multiple subcells into one device is a promising way to realize high efficiency organic solar cells. However, current-matching among different subcells remains as the main challenge for organic tandem photovoltaics. Here, we provide a facile approach to achieve a good current matching via engineering the chemical composition of non-fullerene ternary blend subcells. For the front subcell, a ternary blend of PDBT-T1:TPH-Se:ITIC is selected due to its good thermal stability. The amorphous nature of TPH-Se can sufficiently suppress the unfavorable phase separation of blends during the heat treatment, enabling a sintering in the fabrication of high quality interconnecting layer. A double-junction tandem device is fabricated with a rear subcell consisting of PBDB-T:ITIC. After the optimization of the chemical composition of the front subcell, the power conversion efficiency (PCE) of double-junction tandem device increased from 10.6% using PDBT-T1:TPH-Se binary front subcell to 11.5% using PDBT-T1:TPH-Se:ITIC (1:0.9:0.1) ternary front subcell due to better current matching. In order to further enhance the light absorption in the near-infrared region, a third junction PBDTTT-EFT:IEICO-4F is introduced. The champion cell of triple-junction non-fullerene tandem solar cell achieves a PCE of 13.0% with a high open circuit voltage of 2.52 V.

Efficient Planar Perovskite Solar Cells with Improved Fill Factor via Interface Engineering with Graphene.

Organic-inorganic hybrid lead halide perovskites have been widely investigated in optoelectronics both experimentally and theoretically. The present work incorporates chemically modified graphene into nanocrystal SnO2 as the electron transporting layer (ETL) for highly efficient planar perovskite solar cells. The modification of SnO2 with highly conductive two-dimensional naphthalene diimide-graphene can increase surface hydrophobicity and form van der Waals interaction between the surfactant and the organic-inorganic hybrid lead halide perovskite compounds. As a result, highly efficient perovskite solar cells with power conversion efficiency of 20.2% can be achieved with an improved fill factor of 82%, which could be mainly attributed to the augmented charge extraction and transport.

High Mobility Indium Oxide Electron Transport Layer for an Efficient Charge Extraction and Optimized Nanomorphology in Organic Photovoltaics.

The electron transport layer (ETL) plays an important role in determining the device efficiency of organic solar cells (OSCs). A rational design of an ETL for OSCs targets high charge extraction and induction of an optimized active layer morphology. In this Letter, a high mobility In2O3 synthesized via a solution-processed combustion reaction is successfully used as a universal ETL in an organic photovoltaic device. With the modification of a thin layer of polyethylenimine ethoxylated (PEIE), a device based on crystalline In2O3 outperforms its counterpart, ZnO, in both PBDTTT-EFT-based fullerene and nonfullerene systems. As ZnO is replaced by In2O3, the average efficiency increases from 9.5% to 10.5% for PBDTTT-EFT-PC71BM fullerene-based organic solar cells and also increases from 10.8% to 11.5% for PBDTTT-EFT-IEICO-4F nonfullerene-based organic solar cells, respectively. Morphological studies have unraveled the fact that the crystalline In2O3 ETL with highly aligned nanocrystallites has induced the crystallization of polymer into a preferential molecular packing that favors the charge transport across an active layer. From the photophysical study, it is found that charge extraction in the crystalline In2O3 device is significantly faster than in the ZnO device due to the higher mobility of In2O3 and optimized nanomorphology of the active layer.

Tailored Phase Conversion under Conjugated Polymer Enables Thermally Stable Perovskite Solar Cells with Efficiency Exceeding 21.

The precise control of stoichiometric balance and ionic defects on the surface of solution-processed perovskite is critical to the performance and stability of perovskite solar cells (pero-SCs). Here, we introduce a low-cost and stable conjugated donor polymer (PTQ10) as interfacial layer in the planar n-i-p structured pero-SCs. The polymer was applied to the perovskite intermediate phase before the thermal annealing. This treatment significantly reduced the loss of surface organic cation during thermal annealing. Importantly, the kinetics of phase conversion of perovskite was influenced, and perovskite crystal showed a more preferential orientation. Moreover, the polymer proved to be an effective hole extraction layer due to the proper energy alignment with perovskite. Finally, a champion power conversion efficiency of the planar pero-SCs was achieved at 21.2% with a high fill factor of 81.6%. The devices also showed great ambient and thermal stability. This work presents a facile way of perovskite surface control to achieve high-performance pero-SCs.

Pentatricopeptide-repeat family protein RF6 functions with hexokinase 6 to rescue rice cytoplasmic male sterility.

Cytoplasmic male sterility (CMS) has been extensively used for hybrid seed production in many major crops. Honglian CMS (HL-CMS) is one of the three major types of CMS in rice and has contributed greatly to food security worldwide. The HL-CMS trait is associated with an aberrant chimeric mitochondrial transcript, atp6-orfH79, which causes pollen sterility and can be rescued by two nonallelic restorer-of-fertility (Rf) genes, Rf5 or Rf6. Here, we report the identification of Rf6, which encodes a novel pentatricopeptide repeat (PPR) family protein with a characteristic duplication of PPR motifs 3-5. RF6 is targeted to mitochondria, where it physically associates with hexokinase 6 (OsHXK6) and promotes the processing of the aberrant CMS-associated transcript atp6-orfH79 at nucleotide 1238, which ensures normal pollen development and restores fertility. The duplicated motif 3 of RF6 is essential for RF6-OsHXK6 interactions, processing of the aberrant transcript, and restoration of fertility. Furthermore, reductions in the level of OsHXK6 result in atp6-orfH79 transcript accumulation and male sterility. Together these results reveal a novel mechanism for CMS restoration by which RF6 functions with OsHXK6 to restore HL-CMS fertility. The present study also provides insight into the function of hexokinase 6 in regulating mitochondrial RNA metabolism and may facilitate further exploitation of heterosis in rice.