Development and Therapeutic Applications of Precise Gene Editing Technology

The advent of gene editing represents one of the most transformative breakthroughs in life science,making genome manipulation more accessible than ever before.While traditional CRISPR/Cas-based gene editing,which involves double-strand DNA breaks(DSBs),excels at gene disruption,it is less effective for accurate gene modification.The limitation arises because DSBs are primarily repaired via non-homologous end joining(NHEJ),which tends to introduce indels at the break site.While homology directed repair(HDR)can achieve precise editing when a donor DNA template is provided,the reliance on DSBs often results in unintended genome damage.HDR is restricted to specific cell cycle phases,limiting its application.Currently,gene editing has evolved to unprecedented levels of precision without relying on DSB and HDR.The development of innovative systems,such as base editing,prime editing,and CRISPR-associated transposases(CASTs),now allow for precise editing ranging from single nucleotides to large DNA fragments.Base editors(BEs)enable the direct conversion of one nucleotide to another,and prime editors(PEs)further expand gene editing capabilities by allowing for the insertion,deletion,or alteration of small DNA fragments.The CAST system,a recent innovation,allows for the precise insertion of large DNA fragments at specific genomic locations.In recent years,the optimization of these precise gene editing tools has led to significant improvements in editing efficiency,specificity,and versatility,with advancements such as the creation of base editors for nucleotide transversions,enhanced prime editing systems for more efficient and precise modifications,and refined CAST systems for targeted large DNA insertions,expanding the range of applications for these tools.Concurrently,these advances are complemented by significant improvements in in vivo delivery methods,which have paved the way for therapeutic application of precise gene editing tools.Effective delivery systems are critical for the success of gene therapies,and recent developments in both viral and non-viral vectors have improved the efficiency and safety of gene editing.For instance,adeno-associated viruses(AAVs)are widely used due to their high transfection efficiency and low immunogenicity,though challenges such as limited cargo capacity and potential for immune responses remain.Non-viral delivery systems,including lipid nanoparticles(LNPs),offer an alternative with lower immunogenicity and higher payload capacity,although their transfection efficiency can be lower.The therapeutic potential of these precise gene editing technologies is vast,particularly in treating genetic disorders.Preclinical studies have demonstrated the effectiveness of base editing in correcting genetic mutations responsible for diseases such as cardiomyopathy,liver disease,and hereditary hearing loss.These technologies promise to treat symptoms and potentially cure the underlying genetic causes of these conditions.Meanwhile,challenges remain,such as optimizing the safety and specificity of gene editing tools,improving delivery systems,and overcoming off-target effects,all of which are critical for their successful application in clinical settings.In summary,the continuous evolution of precise gene editing technologies,combined with advancements in delivery systems,is driving the field toward new therapeutic applications that can potentially transform the treatment of genetic disorders by targeting their root causes.

Germline Gene-Editing Creates Enhanced Livestock-Technical and Especially Ethical Issues Challenge Its Use in Humans

Using clustered regularly interspaced short palindromic repeats(CRISPR)-based molecular tools,scientists are engineering-as they are also doing with plants.-animals with advantageous traits,like disease resistance and improved food yield.While these innovative techniques could one day be applied in humans,technical hurdles and ethical concerns likely place this possibility far in the future,The enhancements rely on germline gene editing,which alters the genes in a way that passes the changes on to offspring.Ger m-line gene editing differs from the somatic cell gene editing used in the highly promising new treatment recently approved for the human disease sickle cell anemia.

Achieving structurally stable O3-type layered oxide cathodes through site-specific cation-anion co-substitution for sodium-ion batteries

O3-type layered oxides have garnered great attention as cathode materials for sodium-ion batteries because of their abundant reserves and high theoretical capacity.However,challenges persist in the form of uncontrollable phase transitions and intricate Na^(+)diffusion pathways during cycling,resulting in compromised structural stability and reduced capacity over cycles.This study introduces a special approach employing site-specific Ca/F co-substitution within the layered structure of O_(3)-NaNi_(0.5)Mn_(0.5)O_(2) to effectively address these issues.Herein,the strategically site-specific doping of Ca into Na sites and F into O sites not only expands the Na^(+)diffusion pathways but also orchestrates a mild phase transition by suppressing the Na^(+)/vacancy ordering and providing strong metal-oxygen bonding strength,respectively.The as-synthesized Na_(0.95)Ca_(0.05)Ni_(0.5)Mn_(0.5)O_(1.95)F_(0.05)(NNMO-CaF)exhibits a mild O3→O3+O'3→P3 phase transition with minimized interlayer distance variation,leading to enhanced structural integrity and stability over extended cycles.As a result,NNMO-CaF delivers a high specific capacity of 119.5 mA h g^(-1)at a current density of 120 mA g^(-1)with a capacity retention of 87.1%after 100 cycles.This study presents a promising strategy to mitigate the challenges posed by multiple phase transitions and augment Na^(+)diffusion kinetics,thus paving the way for high-performance layered cathode materials in sodium-ion batteries.

Development of an Agrobacterium-mediated CRISPR/Cas9 gene editing system in jute(Corchorus capsularis)

Jute(Corchorus capsularis L.)is the second most important natural plant fiber source after cotton.However,developing an efficient gene editing system for jute remains a challenge.In this study,the transgenic hairy root system mediated by Agrobacterium rhizogenes strain K599 was developed for Meifeng 4,an elite jute variety widely cultivated in China.The transgenic hairy root system for jute was verified by subcellular localization and bimolecular fluorescence complementation(BiFC)assays.The CHLOROPLASTOS ALTERADOS 1(CcCLA1)gene,which is involved in the development of chloroplasts,was targeted for editing at two sites in Meifeng 4.Based on this hairy root transformation,the gRNA scaffold was placed under the control of cotton ubiquitin GhU6.7 and-GhU6.9 promoters,respectively,to assess the efficiency of gene editing.Results indicated the 50.0%(GhU6.7)and 38.5%(GhU6.9)editing events in the target 2 alleles(gRNA2),but no mutation was detected in the target 1 allele(gRNA1)in transgenic-positive hairy roots.CcCLA1 gene editing at gRNA2 under the control of GhU6.7 in Meifeng 4 was also carried out by Agrobacterium tumefaciens-mediated transformation.Two CcCLA1 mutants were albinic,with a gene editing efficiency of 5.3%.These findings confirm that the CRISPR/Cas9 system,incorporating promoter GhU6.7,can be used as a gene editing tool for jute.

A simple and efficient CRISPR/Cas9 system permits ultra-multiplex genome editing in plants

The development and maturation of the CRISPR/Cas genome editing system provides a valuable tool for plant functional genomics and genetic improvement.Currently available genome-editing tools have a limited number of targets,restricting their application in genetic research.In this study,we developed a novel CRISPR/Cas9 plant ultra-multiplex genome editing system consisting of two template vectors,eight donor vectors,four destination vectors,and one primer-design software package.By combining the advantages of Golden Gate cloning to assemble multiple repetitive fragments and Gateway recombination to assemble large fragments and by changing the structure of the amplicons used to assemble sg RNA expression cassettes,the plant ultra-multiplex genome editing system can assemble a single binary vector targeting more than 40 genomic loci.A rice knockout vector containing 49 sg RNA expression cassettes was assembled and a high co-editing efficiency was observed.This plant ultra-multiplex genome editing system advances synthetic biology and plant genetic engineering.

Engineering high amylose and resistant starch in maize by CRISPR/Cas9-mediated editing of starch branching enzymes

To improve the amylose content(AC)and resistant starch content(RSC)of maize kernel starch,we employed the CRISPR/Cas9 system to create mutants of starch branching enzyme I(SBEI)and starch branching enzyme IIb(SBEIIb).A frameshift mutation in SBEI(E1,a nucleotide insertion in exon 6)led to plants with higher RSC(1.07%),lower hundred-kernel weight(HKW,24.71±0.14 g),and lower plant height(PH,218.50±9.42 cm)compared to the wild type(WT).Like the WT,E1 kernel starch had irregular,polygonal shapes with sharp edges.A frameshift mutation in SBEIIb(E2,a four-nucleotide deletion in exon 8)led to higher AC(53.48%)and higher RSC(26.93%)than that for the WT.E2 kernel starch was significantly different from the WT regarding granule morphology,chain length distribution pattern,X-ray diffraction pattern,and thermal characteristics;the starch granules were more irregular in shape and comprised typical B-type crystals.Mutating SBEI and SBEIIb(E12)had a synergistic effect on RSC,HKW,PH,starch properties,and starch biosynthesis-associated gene expression.SBEIIa,SS1,SSIIa,SSIIIa,and SSIIIb were upregulated in E12 endosperm compared to WT endosperm.This study lays the foundation for rapidly improving the starch properties of elite maize lines.

Metabolic engineering and genome editing strategies for enhanced lipid production in microalgae

Depleting global petroleum reserves and skyrocketing prices coupled with succinct supply have been a grave concern,which needs alternative sources to conventional fuels.Oleaginous microalgae have been explored for enhanced lipid production,leading towards biodiesel production.These microalgae have short life cycles,require less labor,and space,and are easy to scale up.Triacylglycerol,the primary source of lipids needed to produce biodiesel,is accumulated by most microalgae.The article focuses on different types of oleaginous microalgae,which can be used as a feedstock to produce biodiesel.Lipid biosynthesis in microalgae occurs through fatty acid synthesis and TAG synthesis approaches.In-depth discussions are held regarding other efficient methods for enhancing fatty acid and TAG synthesis,regulating TAG biosynthesis bypass methods,blocking competing pathways,multigene approach,and genome editing.The most potential targets for gene transformation are hypothesized to be a malic enzyme and diacylglycerol acyltransferase while lowering phosphoenolpyruvate carboxylase activity is reported to be advantageous for lipid synthesis.

Development of a single transcript CRISPR/Cas9 toolkit for efficient genome editing in autotetraploid alfalfa

Alfalfa(Medicago sativa.L.)is a globally significant autotetraploid legume forage crop.However,despite its importance,establishing efficient gene editing systems for cultivated alfalfa remains a formidable challenge.In this study,we pioneered the development of a highly effective ultrasonic-assisted leaf disc transformation system for Gongnong 1 alfalfa,a variety widely cultivated in Northeast China.Subsequently,we created a single transcript CRISPR/Cas9(CRISPR_2.0)toolkit,incorporating multiplex gRNAs,designed for gene editing in Gongnong 1.Both Cas9 and gRNA scaffolds were under the control of the Arabidopsis ubiquitin-10 promoter,a widely employed polymeraseⅡconstitutive promoter known for strong transgene expression in dicots.To assess the toolkit’s efficiency,we targeted PALM1,a gene associated with a recognizable multifoliate phenotype.Utilizing the CRISPR_2.0 toolkit,we directed PALM1 editing at two sites in the wild-type Gongnong 1.Results indicated a 35.1%occurrence of editing events all in target 2 alleles,while no mutations were detected at target 1 in the transgenic-positive lines.To explore more efficient sgRNAs,we developed a rapid,reliable screening system based on Agrobacterium rhizogenes-mediated hairy root transformation,incorporating the visible reporter MtLAP1.This screening system demonstrated that most purple visible hairy roots underwent gene editing.Notably,sgRNA3,with an 83.0%editing efficiency,was selected using the visible hairy root system.As anticipated,tetra-allelic homozygous palm1 mutations exhibited a clear multifoliate phenotype.These palm1 lines demonstrated an average crude protein yield increase of 21.5%compared to trifoliolate alfalfa.Our findings highlight the modified CRISPR_2.0 system as a highly efficient and robust gene editing tool for autotetraploid alfalfa.

New insights into ATR inhibition in muscle invasive bladder cancer:The role of apolipoprotein B mRNA editing catalytic subunit 3B

Background:Apolipoprotein B mRNA editing catalytic polypeptide(APOBEC),an endogenous mutator,induces DNA damage and activates the ataxia telangiectasia and Rad3-related(ATR)-checkpoint kinase 1(Chk1)pathway.Although cisplatin-based therapy is the mainstay for muscle-invasive bladder cancer(MIBC),it has a poor survival rate.Therefore,this study aimed to evaluate the efficacy of an ATR inhibitor combined with cisplatin in the treatment of APOBEC catalytic subunit 3B(APOBEC3B)expressing MIBC.Methods:Immunohistochemical staining was performed to analyze an association between APOBEC3B and ATR in patients with MIBC.The APOBEC3B expression in MIBC cell lines was assessed using real-time polymerase chain reaction and western blot analysis.Western blot analysis was performed to confirm differences in phosphorylated Chk1(pChk1)expression according to the APOBEC3B expression.Cell viability and apoptosis analyses were performed to examine the anti-tumor activity of ATR inhibitors combined with cisplatin.Results:There was a significant association between APOBEC3B and ATR expression in the tumor tissues obtained from patients with MIBC.Cells with higher APOBEC3B expression showed higher pChk1 expression than cells expressing low APOBEC3B levels.Combination treatment of ATR inhibitor and cisplatin inhibited cell growth in MIBC cells with a higher APOBEC3B expression.Compared to cisplatin single treatment,combination treatment induced more apoptotic cell death in the cells with higher APOBEC3B expression.Conclusion:Our study shows that APOBEC3B’s higher expression status can enhance the sensitivity of MIBC to cisplatin upon ATR inhibition.This result provides new insight into appropriate patient selection for the effective application of ATR inhibitors in MIBC.

Targeted protein editing technique in living mammalian cells by peptide-fused PNGase

Various precise gene editing techniques at the DNA/RNA level,driven by clustered regularly interspaced short palindrome repeats(CRISPR)/CRISPR-associated protein 9(Cas9)technology,have gained significant prominence.Yet,research on targeted protein editing techniques remains limited.Only a few attempts have been made,including the use of specific proteases and de-O-glycosylating enzymes as editing enzymes.Here,we propose direct editing of Nglycosylated proteins using de-N-glycosylating enzymes to modify N-glycosylation and simultaneously alter the relevant asparagine residue to aspartate in living cells.Selective protein deglycosylation editors were developed by fusing high-affinity protein-targeting peptides with active peptide:N-glycanases(PNGases).Three crucial cell membrane proteins,programmed cell death protein-1(PD-1),programmed cell death-1 ligand 1(PD-L1),and severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)spike protein,were chosen to be tested as a proof of concept.N-linked glycans were removed,and the relevant sites were converted from Asn to Asp in living mammalian cells,destabilizing target proteins and accelerating their degradation.Further investigation focused on SARS-CoV-2 spike protein deglycosylation editing.The collaboration of LCB1-PNGase F(PNGF)effectively reduced syncytia formation,inhibited pseudovirus packaging,and significantly hindered virus entry into host cells,which provides insights for coronavirus disease 2019(COVID-19)treatment.This tool enables editing protein sequences post-de-N-glycosylation in living human cells,shedding light on protein N-glycosylation functions,and Asn to Asp editing in organisms.It also offers the potential for developing protein degradation technologies.

Recent advances in CRISPR-based genome editing technology and its applications in cardiovascular research

The rapid development of genome editing technology has brought major breakthroughs in the fields of life science and medicine. In recent years, the clustered regularly interspaced short palindromic repeats(CRISPR)-based genome editing toolbox has been greatly expanded, not only with emerging CRISPR-associated protein(Cas) nucleases, but also novel applications through combination with diverse effectors. Recently, transposon-associated programmable RNA-guided genome editing systems have been uncovered, adding myriads of potential new tools to the genome editing toolbox. CRISPR-based genome editing technology has also revolutionized cardiovascular research. Here we first summarize the advances involving newly identified Cas orthologs, engineered variants and novel genome editing systems, and then discuss the applications of the CRISPR-Cas systems in precise genome editing, such as base editing and prime editing. We also highlight recent progress in cardiovascular research using CRISPR-based genome editing technologies, including the generation of genetically modified in vitro and animal models of cardiovascular diseases(CVD) as well as the applications in treating different types of CVD. Finally, the current limitations and future prospects of genome editing technologies are discussed.

Agrobacterium tumefaciens-mediated transformation of embryogenic callus and CRISPR/Cas9-mediated genome editing in‘Feizixiao'litchi

Litchi(Litchi chinensis Sonn.)is a type of commercially prevalent subtropical and tropical fruit.Since litchi has a highly heterozygous genetic background and a long reproductive cycle,conventional breeding methods(such as hybridization)have limited ability to nurture new litchi cultivars.Here,an efficient and stable Agrobacterium tumefaciens-mediated genetic transformation of embryogenic callus was established in‘Feizixiao’litchi.Transgenic materials were verified using polymerase chain reaction(PCR)analysis,β-glucuronidase(GUS)assay,and green fluorescent protein(GFP)assay.To implement the technology of the Clustered Regularly Interspaced Short Palindromic Repeats(CRISPR)/associated protein 9(CRISPR/Cas9)technology in‘Feizixiao’litchi and verify the validity of these transformation systems,the litchi polyphenol oxidase gene(LcPPO,JF926153)was knocked out.Various categories of mutations,covering base insertions,deletions,and substitutions,were found in transgenic materials via sequence analysis.The transformation system achieved high feasibility and efficiency,and the system of CRISPR/Cas9 was successfully employed to edit genes in‘Feizixiao’litchi.This work provides an essential foundation for investigating the functions of genes and accelerating litchi genetic improvement.

Three novel alleles of OsGS1 developed by base-editing-mediated artificial evolution confer glufosinate tolerance in rice

Only few glufosinate-tolerant genes,such as phosphinothricin acetyltransferase(PAT)and bialaphos resistance(bar)identified from Streptomyces,are currently available for developing genetically modified rice in agricultural application.Following the rapid development of genome editing technology,generation of novel glufosinate-tolerant gene resources through artificial evolution of endogenous genes is more promising and highly desirable in rice molecular breeding program.In this study,the endogenous Glutamine synthetase1(OsGS1)was artificially evolved by base-editing-mediated gene evolution(BEMGE)in rice cells to create novel alleles conferring glufosinate tolerance in rice germplasms.Two novel glufosinate-tolerant OsGS1 alleles(OsGS1-AVPS and OsGS1-+AF)and one reported tolerant allele(OsGS1-SGTA)were successfully identified from approximately 4200 independent hygromycin-tolerant calli.Germination assays and spray tests revealed that these three OsGS1 alleles confer glufosinate tolerance in rice.Furthermore,OsGS1-AVPS and OsGS1-SGTA were quickly deployed into the elite rice cultivar Nangeng 46 through precise base editing.Overall,our results demonstrate the feasibility of developing glufosinate-tolerant rice by editing an endogenous rice gene in molecular breeding programs.

An efficient transient gene expression system for protein subcellular localization assay and genome editing in citrus protoplasts

Protoplast has been widely used in biotechnologies to circumvent the breeding obstacles in citrus, including long juvenility, polyembryony, and male/female sterility. The protoplast-based transient gene expression system is a powerful tool for gene functional characterization and CRISPR/Cas9 genome editing in higher plants, but it has not been widely used in citrus. In this study, the polyethylene glycol(PEG)-mediated method was optimized for citrus callus protoplast transfection, with an improved transfection efficiency of 68.4%. Consequently, the efficiency of protein subcellular localization assay was increased to 65.8%, through transient expression of the target gene in protoplasts that stably express the fluorescent organelle marker protein. The gene editing frequencies in citrus callus protoplasts reached 14.2% after transient expression of CRISPR/Cas9 constructs. We demonstrated that the intronic polycistronic tRNAgRNA(inPTG) genome editing construct was functional in both the protoplast transient expression system and epicotyl stable transformation system in citrus. With this optimized protoplast transient expression system, we improved the efficiency of protein subcellular localization assay and developed the genome editing system in callus protoplasts, which provides an approach for prompt test of CRISPR vectors.

DNA-free genome editing in grapevine using CRISPR/Cas9 ribonucleoprotein complexes followed by protoplast regeneration

CRISPR/Cas9 genome editing technology can overcome many limitations of traditional breeding,offering enormous potential for crop improvement and food production.Although the direct delivery of Cas9-single guide RNA(sgRNA)ribonucleoprotein(RNP)complexes to grapevine(Vitis vinifera)protoplasts has been shown before,the regeneration of edited protoplasts into whole plants has not been reported.Here,we describe an efficient approach to obtain transgene-free edited grapevine plants by the transfection and subsequent regeneration of protoplasts isolated from embryogenic callus.As proof of concept,a single-copy green f luorescent protein reporter gene(GFP)in the grapevine cultivar Thompson Seedless was targeted and knocked out by the direct delivery of RNPs to protoplasts.CRISPR/Cas9 activity,guided by two independent sgRNAs,was confirmed by the loss of GFP f luorescence.The regeneration of GFP−protoplasts into whole plants was monitored throughout development,confirming that the edited grapevine plants were comparable in morphology and growth habit to wild-type controls.We report the first highly efficient protocol for DNA-free genome editing in grapevine by the direct delivery of preassembled Cas9-sgRNA RNP complexes into protoplasts,helping to address the regulatory concerns related to genetically modified plants.This technology could encourage the application of genome editing for the genetic improvement of grapevine and other woody crop plants.

Mitochondrial RNA editing sites affect the phylogenetic reconstruction of gymnosperms

RNA editing is a post-transcriptional process that alters the genetic information of mRNAs,so that the translated proteins deviate from those predicted by the genomic DNA templates.RNA editing occurs in a wide range of eukaryotes,including protists,multicellular animals,and land plants(Gray,2012;Ichinose and Sugita,2016).RNA editing in animals,dominated by A-to-I synonymous editing with low editing efficiency(20e30%),might play important roles in the regulation of gene expression(Wang et al.,2013).In contrast,RNA editing in plant organelles is usually nonsynonymous,affecting mostly the 2nd and 1st codon positions with very high editing efficiency(~80%).In plants,RNA editing is thought to affect plant phenotype and growth by restoring evolutionarily conserved amino acids and ensuring the correct folding of trans-membrane proteins on the respiratory chain complex(Sloan,2017).

Os DXR interacts with Os MORF1 to regulate chloroplast development and the RNA editing of chloroplast genes in rice

Plant chlorophyll biosynthesis and chloroplast development are two complex processes that are regulated by exogenous and endogenous factors. In this study, we identified OsDXR, a gene encoding a reductoisomerase that positively regulates chlorophyll biosynthesis and chloroplast development in rice. OsDXR knock-out lines displayed the albino phenotype and could not complete the whole life cycle process. OsDXR was highly expressed in rice leaves, and subcellular localization indicated that OsDXR is a chloroplast protein. Many genes involved in chlorophyll biosynthesis and chloroplast development were differentially expressed in the OsDXR knock-out lines compared to the wild type.Moreover, we found that the RNA editing efficiencies of ndhA-1019 and rpl2-1 were significantly reduced in the OsDXR knock-out lines. Furthermore, OsDXR interacted with the RNA editing factor OsMORF1 in a yeast two-hybrid screen and bimolecular fluorescence complementation assay. Finally, disruption of the plastidial 2-C-methyl-derythritol-4-phosphate pathway resulted in defects in chloroplast development and the RNA editing of chloroplast genes.

Multiplex gene editing reduces oxalate production in primary hyperoxaluria type 1

Targeting key enzymes that generate oxalate precursors or substrates is an alternative strategy to eliminate primary hyperoxaluria type I(PH1),the most common and lifethreatening type of primary hyperoxaluria.The compact Clustered Regularly Interspaced Short Palindromic Repeats(CRISPR)from the Prevotella and Francisella 1(Cpf1)protein simplifies multiplex gene editing and allows for all-in-one adeno-associated virus(AAV)delivery.We hypothesized that the multiplex capabilities of the Cpf1system could help minimize oxalate formation in PH1 by simultaneously targeting the hepatic hydroxyacid oxidase 1(Hao1)and lactate dehydrogenase A(Ldha)genes.Study cohorts included treated PH1 rats(Agxt Q84X rats injected with AAV-AsCpf1 at 7 days of age),phosphate-buffered saline(PBS)-injected PH1 rats,untreated PH1 rats,and age-matched wild-type(WT)rats.The most efficient and specific CRISPR RNA(crRNA)pairs targeting the rat Hao1and Ldha genes were initially screened ex vivo.In vivo experiments demonstrated efficient genome editing of the Hao1 and Ldha genes,primarily resulting in small deletions.This resulted in decreased transcription and translational expression of Hao1 and Ldha.Treatment significantly reduced urine oxalate levels,reduced kidney damage,and alleviated nephrocalcinosis in rats with PH1.No liver toxicity,ex-liver genome editing,or obvious offtarget effects were detected.We demonstrated the AAVAsCpf1 system can target multiple genes and rescue the pathogenic phenotype in PH1,serving as a proof-ofconcept for the development of multiplex genome editingbased gene therapy.

OsPPR9 encodes a DYW-type PPR protein that affects editing efficiency of multiple RNA editing sites and is essential for chloroplast development

Photosynthesis occurs mainly in chloroplasts,whose development is regulated by proteins encoded by nuclear genes.Among them,pentapeptide repeat(PPR)proteins participate in organelle RNA editing.Although there are more than 450 members of the PPR protein family in rice,only a few affect RNA editing in rice chloroplasts.Gene editing technology has created new rice germplasm and mutants,which could be used for rice breeding and gene function study.This study evaluated the functions of OsPPR9 in chloroplast RNA editing in rice.The osppr9 mutants were obtained by CRISPR/Cas9,which showed yellowing leaves and a lethal phenotype,with suppressed expression of genes associated with chloroplast development and accumulation of photosynthetic-related proteins.In addition,loss of OsPPR9 protein function reduces the editing efficiency of rps8-C182,rpoC2-C4106,rps14-C80,and ndhB-C611 RNA editing sites,which affects chloroplast growth and development in rice.Our data showed that OsPPR9 is highly expressed in rice leaves and encodes a DYW-PPR protein localized in chloroplasts.Besides,the OsPPR9 protein was shown to interact with OsMORF2 and OsMORF9.Together,our findings provide insights into the role of the PPR protein in regulating chloroplast development in rice.

Development and Application of Prime Editing in Plants

Clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein(Cas)-mediated genome editing has greatly accelerated progress in plant genetic research and agricultural breeding by enabling targeted genomic modifications.Moreover,the prime editing system,derived from the CRISPR/Cas system,has opened the door for even more precise genome editing.Prime editing has the capability to facilitate all 12 types of base-to-base conversions,as well as desired insertions or deletions of fragments,without inducing double-strand breaks and requiring donor DNA templet.In a short time,prime editing has been rapidly verified as functional in various plants,and can be used in plant genome functional analysis as well as precision breeding of crops.In this review,we summarize the emergence and development of prime editing,highlight recent advances in improving its efficiency in plants,introduce the current applications of prime editing in plants,and look forward to future prospects for utilizing prime editing in genetic improvement and precision molecular breeding.