Regeneration of non-chimeric plants from DNA-free edited grapevine protoplasts

Establishing a reliable protoplast system for grapevine: isolation, transformation, and callus induction

Protoplasts are single cells enclosed by the plasma membrane after cell wall removal. They are widely used in various biotechnological applications, including gene functional analysis, verification of genome editing reagents, and plant regeneration. Recent advances in genome editing have enabled the production of non-chimeric and transgene-free genome-edited plants using protoplasts. This process involves protoplast isolation, transformation, and regeneration, requiring advanced technical skills. Challenges in isolation and regeneration have limited their use in genome editing. In grapevines, however, very few studies have reported the use of protoplasts isolated from leaves. Efficient isolation and transformation protocols for Chardonnay remain lacking and require cultivar-specific optimization. In this study, we established a reliable and efficient protoplast isolation and transformation system by optimizing conditions for protoplast isolation and PEG-mediated transformation in Chardonnay cultivar. The yield of viable protoplasts was approximately 75 × 106 per gram of leaf material, with a viability of 91%. A transformation efficiency of 87% was achieved under the optimized conditions. To evaluate the regeneration ability of mesophyll protoplast, transformed and untransformed protoplasts were cultured on solid and liquid MS media supplemented with 2 mg/L 2,4-D and 0.5 mg/L BA to facilitate microcalli formation. Microcalli formed on the feeder layer and developed into calli when transferred to liquid MS culture with 2 mg/L 2,4-D and 0.5 mg/L BA. However, the calli were unable to regenerate into roots or shoots. These findings provide a foundation for further optimization of protoplast-based regeneration systems in grapevines, with the potential to enhance genome editing applications in this species.

Unlocking male sterility in horticultural crops through gene editing technology for precision breeding applications: presentation of a case study in tomato

Plant male sterility (MS) refers to the failure of the production of functional anthers, viable pollen grains and/or fertile sperm cells. This feature has great potential in horticultural crops for the exploitation of heterosis through the development of F1 hybrid varieties. MS in plants can occur spontaneously or can be induced artificially by exploiting biotechnological tools, such as the editing of genes involved in spore formation or pollen development. The success of such an approach strongly depends both on preliminary knowledge of the involved genes and on effective procedures for in vitro transfection/regeneration of whole plants. Furthermore, according to previous studies based on CRISPR/Cas9 technology, the efficacy of targeting and the resulting mutation profile are critically influenced by intrinsic factors, such as the CRISPR target primary sequence sites and chromatin signatures, which are often associated with varying levels of chromatin accessibility across different genomic regions. This relationship underscores the complexity of CRISPR-based genome editing and highlights the need to identify a precise suitable target. Our paper reports the results obtained for site-specific in vivo mutagenesis via a CRISPR/Cas9-mediated strategy applied to the MYB80 gene, which is a promising target for implementing male sterility in horticultural crops. We highlight the main steps that play a key role in the whole experimental pipeline, which aims at the generation of CRISPR/Cas-edited DNA-free tomato plants. This goal was achieved via protoplast-based technology and by directly delivering a ribonucleoprotein complex consisting of the Cas9 protein and in vitro synthesized single guide RNAs that can target different positions of the gene under investigation. Overall findings and insights are presented and critically discussed.

Advances in the molecular mechanism of grapevine resistance to fungal diseases

Grapevine is an important economic fruit tree worldwide, but grape production has been plagued by a vast number of fungal diseases, which affect tree vigor and the quality and yield of berries. To seek remedies for such issues, researchers have always been committed to conventional and biotechnological breeding. In recent years, increasing progress has been made in elucidating the molecular mechanisms of grape-pathogenic fungi interactions and resistance regulation. Here, we summarize the current knowledge on the molecular basis of grapevine resistance to fungal diseases, including fungal effector-mediated susceptibility and resistance, resistant regulatory networks in grapevine, innovative approaches of genetic transformation, and strategies to improve grape resistance. Understanding the molecular basis is important for exploring and accurately regulating grape resistance to fungal diseases.

CRISPR/Cas9-driven double modification of grapevine MLO6-7 imparts powdery mildew resistance, while editing of NPR3 augments powdery and downy mildew tolerance

The implementation of genome editing strategies in grapevine is the easiest way to improve sustainability and resilience while preserving the original genotype. Among others, the Mildew Locus-O (MLO) genes have already been reported as good candidates to develop powdery mildew-immune plants. A never-explored grapevine target is NPR3, a negative regulator of the systemic acquired resistance. We report the exploitation of a cisgenic approach with the Cre-lox recombinase technology to generate grapevine-edited plants with the potential to be transgene-free while preserving their original genetic background. The characterization of three edited lines for each target demonstrated immunity development against Erysiphe necator in MLO6-7-edited plants. Concomitantly, a significant improvement of resilience, associated with increased leaf thickness and specific biochemical responses, was observed in defective NPR3 lines against E. necator and Plasmopara viticola. Transcriptomic analysis revealed that both MLO6-7 and NPR3 defective lines modulated their gene expression profiles, pointing to distinct though partially overlapping responses. Furthermore, targeted metabolite analysis highlighted an overaccumulation of stilbenes coupled with an improved oxidative scavenging potential in both editing targets, likely protecting the MLO6-7 mutants from detrimental pleiotropic effects. Finally, the Cre-loxP approach allowed the recovery of one MLO6-7 edited plant with the complete removal of transgene. Taken together, our achievements provide a comprehensive understanding of the molecular and biochemical adjustments occurring in double MLO-defective grape plants. In parallel, the potential of NPR3 mutants for multiple purposes has been demonstrated, raising new questions on its wide role in orchestrating biotic stress responses.

A Comparison of DNA-Methylation during Protoplast Culture of Ponkan Mandarin (Citrus reticulata Blanco) and Tobacco (Nicotiana tabacum L.)

The epigenetic variation in protoplast regeneration is a topic that has attracted interest recently. To elucidate the role of DNA methylation in the regeneration of protoplasts from the ponkan (Citrus reticulata), this study employs the methylation-sensitive amplification polymorphism (MSAP) molecular marker technique to analyze changes in DNA methylation levels and patterns during the isolation and culture of protoplasts from ponkan and tobacco. Additionally, differential DNA methylation fragments are cloned, sequenced, and subjected to bioinformatics analysis. The results reveal that, for non-regenerable ponkan mesophyll protoplasts, DNA methylation levels increase by 3.98% after isolation and then show a trend of initial decrease followed by an increase during culture. In contrast, for regenerable ponkan callus protoplasts and tobacco mesophyll protoplasts, DNA methylation levels decrease by 1.75% and 2.33%, respectively, after isolation. During culture, the DNA methylation levels of ponkan callus protoplasts first increase and then decrease, while those of tobacco mesophyll protoplasts show an opposite trend of initial decrease followed by an increase. Regarding DNA methylation patterns, ponkan mesophyll protoplasts exhibit primarily hypermethylation changes accompanied by a small amount of gene demethylation, whereas ponkan callus protoplasts are dominated by demethylation changes with some genes undergoing hypermethylation. The methylation exhibits dynamic changes in protoplast isolation regeneration. By recovering, cloning, sequencing, and performing BLASTn alignment analysis on specific methylation modification sites in the ponkan, 18 DNA sequences with high homology are identified which are found to be involved in various biological functions, thereby establishing a foundational basis for genetic editing in protoplasts.

Gene editing by SSB/CRISPR-Cas9 ribonucleoprotein in bacteria

The application of CRISPR-Cas9 ribonucleoprotein (RNP) for gene editing is commonly used in plants and animals, but its application in bacteria has not been reported. In this study, we employed DNA single-strand binding protein (SSB) to construct an SSB/CRISPR-Cas9 RNP-editing system for non-homologous recombination and homologous recombination gene editing of the upp gene in bacteria. The RNP targeting the upp gene, along with SSB, was introduced into the protoplasts of Escherichia coli, Pseudomonas, and Bacillus subtilis. Transformants were obtained on plates containing 5-fluorouracil (5-FU) with gene editing efficiencies (percentage of transformants relative to the number of protoplasts) of 9.75 %, 5.02 %, and 8.37 %, respectively, and sequencing analysis confirmed 100 % non-homologous recombination. When RNP, SSB, and a 100-nucleotide single-stranded oligodeoxynucleotide (ssODN) donor were introduced into the protoplasts of these bacteria, transformants were obtained with editing efficiencies of 45.11 %, 30.13 %, and 27.18 %, respectively, and sequencing confirmed 100 % homologous recombination knockout of the upp gene. Additionally, introducing RNP, SSB, and a 100 base-pair double-stranded oligodeoxynucleotide (dsODN) donor containing a tetracycline resistance gene (tetR-dsODN) resulted in transformants on 5-FU plates with editing efficiencies of 35.94 %, 22.46 %, and 19.08 %, respectively, with sequencing confirming 100 % homologous recombination replacement of the upp gene with tetR. These results demonstrate that the SSB/CRISPR-Cas9 RNP system can efficiently, simply, and rapidly edit bacterial genomes without the need for plasmids. This study is the first to report the use of RNP-based gene editing in bacteria.

A New Approach for CRISPR/Cas9 Editing and Selection of Pathogen-Resistant Plant Cells of Wine Grape cv. 'Merlot'

Grape is one of the most economically significant berry crops. Owing to the biological characteristics of grapes, such as the long juvenile period (5-8 years), high degree of genome heterozygosity, and the frequent occurrence of inbreeding depression, homozygosity during crossbreeding leads to loss of varietal characteristics and viability. CRISPR/Cas editing has become the tool of choice for improving elite technical grape varieties. This study provides the first evidence of a decrease in the total fraction of phenolic compounds and an increase in the concentration of peroxide compounds in grape callus cells upon the addition of chitosan to the culture medium. These previously unreported metabolic features of the grape response to chitosan have been described and used for the first time to increase the probability of selecting plant cells with MLO7 knockout characterised by an oxidative burst in response to the presence of a pathogen modulated by chitosan in the high-metabolite black grape variety 'Merlot'. This was achieved by using a CRISPR/Cas9 editing vector construction with the peroxide sensor HyPer as a reporter. This research represents the first CRISPR/Cas9 editing of 'Merlot', one of the most economically important elite technical grape varieties.

Modern Technologies Provide New Opportunities for Somatic Hybridization in the Breeding of Woody Plants

Advances in cell fusion technology have propelled breeding into the realm of somatic hybridization, enabling the transfer of genetic material independent of sexual reproduction. This has facilitated genome recombination both within and between species. Despite its use in plant breeding for over fifty years, somatic hybridization has been limited by cumbersome procedures, such as protoplast isolation, hybridized-cell selection and cultivation, and regeneration, particularly in woody perennial species that are difficult to regenerate. This review summarizes the development of somatic hybridization, explores the challenges and solutions associated with cell fusion technology in woody perennials, and outlines the process of protoplast regeneration. Recent advancements in genome editing and plant cell regeneration present new opportunities for applying somatic hybridization in breeding. We offer a perspective on integrating these emerging technologies to enhance somatic hybridization in woody perennial plants.

Genome editing of a recalcitrant wine grape genotype by lipofectamine-mediated delivery of CRISPR/Cas9 ribonucleoproteins to protoplasts

The main bottleneck in the application of biotechnological breeding methods to woody species is due to the in vitro regeneration recalcitrance shown by several genotypes. On the other side, woody species, especially grapevine (Vitis vinifera L.), use most of the pesticides and other expensive inputs in agriculture, making the development of efficient approaches of genetic improvement absolutely urgent. Genome editing is an extremely promising technique particularly for wine grape genotypes, as it allows to modify the desired gene in a single step, preserving all the quality traits selected and appreciated in elite varieties. A genome editing and regeneration protocol for the production of transgene-free grapevine plants, exploiting the lipofectamine-mediated direct delivery of CRISPR-Cas9 ribonucleoproteins (RNPs) to target the phytoene desaturase gene, is reported. We focused on Nebbiolo (V. vinifera), an extremely in vitro recalcitrant wine genotype used to produce outstanding wines, such as Barolo and Barbaresco. The use of the PEG-mediated editing method available in literature and employed for highly embryogenic grapevine genotypes did not allow the proper embryo development in the recalcitrant Nebbiolo. Lipofectamines, on the contrary, did not have a negative impact on protoplast viability and plant regeneration, leading to the obtainment of fully developed edited plants after about 5 months from the transfection. Our work represents one of the first examples of lipofectamine use for delivering editing reagents in plant protoplasts. The important result achieved for the wine grape genotype breeding could be extended to other important wine grape varieties and recalcitrant woody species.

Cationic lipid nanoparticle-mediated delivery of a Cas9/crRNA ribonucleoprotein complex for transgene-free editing of the citrus plant genome

KEY MESSAGE

A lipofectamine-mediated transfection protocol for DNA-free genome editing of citrus protoplast cells using a Cas9/gRNA ribonucleoprotein (RNP) complex resulted in the production of transgene free genome edited citrus.

Editing VvDXS1 for the creation of muscat flavour in Vitis vinifera cv. Scarlet Royal

Muscat flavour represents a group of unique aromatic attributes in some grape varieties. Biochemically, grape berries with muscat flavour produce high levels of monoterpenes. Monoterpene biosynthesis is mainly through the DOXP/MEP pathway, and VvDXS1 encodes the first enzyme in this plastidial pathway of terpene biosynthesis in grapevine. A single-point mutation resulting in the substitution of a lysine with an asparagine at position 284 in the VvDXS1 protein has previously been identified as the major cause for producing muscat flavour in grapes. In this study, the same substitution in the VvDXS1 protein was successfully created through prime editing in the table grape Vitis vinifera cv. 'Scarlet Royal'. The targeted point mutation was detected in most of the transgenic vines, with varying editing efficiencies. No unintended mutations were detected in the edited alleles, either by PCR Sanger sequencing or by amplicon sequencing. More than a dozen edited vines were identified with an editing efficiency of more than 50%, indicating that these vines were likely derived from single cells in which one allele was edited. These vines had much higher levels of monoterpenes in their leaves than the control, similar to what was found in leaf samples between field-grown muscat and non-muscat grapes.

CRISPR/Cas9 editing of Downy mildew resistant 6 (DMR6-1) in grapevine leads to reduced susceptibility to Plasmopara viticola

Downy mildew of grapevine (Vitis vinifera), caused by the oomycete Plasmopara viticola, is an important disease that is present in cultivation areas worldwide, and using resistant varieties provides an environmentally friendly alternative to fungicides. DOWNY MILDEW RESISTANT 6 (DMR6) from Arabidopsis is a negative regulator of plant immunity and its loss of function confers resistance to downy mildew. In grapevine, DMR6 is present in two copies, named VvDMR6-1 and VvDMR6-2. Here, we describe the editing of VvDMR6-1 in embryogenic calli using CRISPR/Cas9 and the regeneration of the edited plants. All edited plants were found to be biallelic and chimeric, and whilst they all showed reduced growth compared with non-transformed control plants, they also had reduced susceptibility to P. viticola. Comparison between mock-inoculated genotypes showed that all edited lines presented higher levels of salicylic acid than controls, and lines subjected to transformation presented higher levels of cis-resveratrol than controls. Our results identify VvDMR6-1 as a promising target for breeding grapevine cultivars with improved resistance to downy mildew.

New improvements in grapevine genome editing: high efficiency biallelic homozygous knock-out from regenerated plantlets by using an optimized zCas9i

BACKGROUND

For ten years, CRISPR/cas9 system has become a very useful tool for obtaining site-specific mutations on targeted genes in many plant organisms. This technology opens up a wide range of possibilities for improved plant breeding in the future. In plants, the CRISPR/Cas9 system is mostly used through stable transformation with constructs that allow for the expression of the Cas9 gene and sgRNA. Numerous studies have shown that site-specific mutation efficiency can vary greatly between different plant species due to factors such as plant transformation efficiency, Cas9 expression, Cas9 nucleotide sequence, the addition of intronic sequences, and many other parameters. Since 2016, when the first edited grapevine was created, the number of studies using functional genomic approaches in grapevine has remained low due to difficulties with plant transformation and gene editing efficiency. In this study, we optimized the process to obtain site-specific mutations and generate knock-out mutants of grapevine (Vitis vinifera cv. 'Chardonnay'). Building on existing methods of grapevine transformation, we improved the method for selecting transformed plants at chosen steps of the developing process using fluorescence microscopy.

RESULTS

By comparison of two different Cas9 gene and two different promoters, we increased site-specific mutation efficiency using a maize-codon optimized Cas9 containing 13 introns (zCas9i), achieving up to 100% biallelic mutation in grapevine plantlets cv. 'Chardonnay'. These results are directly correlated with Cas9 expression level.

CONCLUSIONS

Taken together, our results highlight a complete methodology for obtaining a wide range of homozygous knock-out mutants for functional genomic studies and future breeding programs in grapevine.

Application of new breeding techniques in fruit trees

Climate change and rapid adaption of invasive pathogens pose a constant pressure on the fruit industry to develop improved varieties. Aiming to accelerate the development of better-adapted cultivars, new breeding techniques have emerged as a promising alternative to meet the demand of a growing global population. Accelerated breeding, cisgenesis, and CRISPR/Cas genome editing hold significant potential for crop trait improvement and have proven to be useful in several plant species. This review focuses on the successful application of these technologies in fruit trees to confer pathogen resistance and tolerance to abiotic stress and improve quality traits. In addition, we review the optimization and diversification of CRISPR/Cas genome editing tools applied to fruit trees, such as multiplexing, CRISPR/Cas-mediated base editing and site-specific recombination systems. Advances in protoplast regeneration and delivery techniques, including the use of nanoparticles and viral-derived replicons, are described for the obtention of exogenous DNA-free fruit tree species. The regulatory landscape and broader social acceptability for cisgenesis and CRISPR/Cas genome editing are also discussed. Altogether, this review provides an overview of the versatility of applications for fruit crop improvement, as well as current challenges that deserve attention for further optimization and potential implementation of new breeding techniques.

Advances in Quercus ilex L. breeding: the CRISPR/Cas9 technology via ribonucleoproteins

The CRISPR/Cas9 ribonucleoprotein (RNP)-mediated technology represents a fascinating tool for modifying gene expression or mutagenesis as this system allows for obtaining transgene-free plants, avoiding exogenous DNA integration. Holm oak (Quercus ilex) has an important social, economic, and ecological role in the Mediterranean climate zones of Western Europe and North Africa and is severely affected by oak decline syndrome. Here we report the first example of the application of the CRISPR/Cas9-RNP technology in holm oak. Firstly, we evaluated the protoplast isolation from both in vitro leaves and proembryogenic masses. Proembryogenic masses represented the best material to get high protoplast yield (11 x 106 protoplasts/ml) and viability. Secondly, the protoplast transfection ability was evaluated through a vector expressing green fluorescence protein as marker gene of transfection, reaching a transfection percentage of 62% after 24 hours. CRISPR/Cas9 RNPs were successfully delivered into protoplasts resulting in 5.6% ± 0.5% editing efficiency at phytoene desaturase (pds) target genomic region. Protoplasts were then cultured in semisolid media and, after 45 days in culture, developed embryogenic calli were observed in a Murashige and Skoog media with half concentration of NH4NO3 and KNO3 supplemented with 0.1 mg/L benzylaminopurine and 0.1 mg/L 2,4-dichlorophenoxyacetic acid.

An efficient protoplast-based genome editing protocol for Vitis species

CRISPR-Cas technologies allow for precise modifications in plant genomes and promise to revolutionize agriculture. These technologies depend on the delivery of editing components into plant cells and the regeneration of fully edited plants. In vegetatively propagated plants, such as grape, protoplast culture provides one of the best avenues for producing non-chimeric and transgene-free genome-edited plants. However, poor regeneration of plants from protoplasts has hindered their implementation for genome editing. Here, we report an efficient protocol for regenerating plants from protoplasts from multiple grape varieties. By encapsulating the protoplasts in calcium alginate beads and co-culturing them with feeder cultures, the protoplasts divide to form callus colonies that regenerate into embryos and ultimately plants. This protocol worked successfully in wine and table grape (Vitis vinifera) varieties, as well as grape rootstocks and the grapevine wild relative Vitis arizonica. Moreover, by transfecting protoplasts with CRISPR-plasmid or ribonucleoprotein (RNP) complexes, we regenerated albino plants with edits in VvPHYTOENE DESATURASE gene in three varieties and in V. arizonica. The results reveal the potential of this platform to facilitate genome editing in Vitis species.

CRISPR/Cas as a Genome-Editing Technique in Fruit Tree Breeding

CRISPR (short for "Clustered Regularly Interspaced Short Palindromic Repeats") is a technology that research scientists use to selectively modify the DNA of living organisms. CRISPR was adapted for use in the laboratory from the naturally occurring genome-editing systems found in bacteria. In this work, we reviewed the methods used to introduce CRISPR/Cas-mediated genome editing into fruit species, as well as the impacts of the application of this technology to activate and knock out target genes in different fruit tree species, including on tree development, yield, fruit quality, and tolerance to biotic and abiotic stresses. The application of this gene-editing technology could allow the development of new generations of fruit crops with improved traits by targeting different genetic segments or even could facilitate the introduction of traits into elite cultivars without changing other traits. However, currently, the scarcity of efficient regeneration and transformation protocols in some species, the fact that many of those procedures are genotype-dependent, and the convenience of segregating the transgenic parts of the CRISPR system represent the main handicaps limiting the potential of genetic editing techniques for fruit trees. Finally, the latest news on the legislation and regulations about the use of plants modified using CRISPR/Cas systems has been also discussed.

Efficient genome editing in grapevine using CRISPR/LbCas12a system

Clustered regularly interspaced short palindromic repeats (CRISPR) /Cas12a system, also known as CRISPR/Cpf1, has been successfully harnessed for genome engineering in many plants, but not in grapevine yet. Here we developed and demonstrated the efficacy of CRISPR/Cas12a from Lachnospiraceae bacterium ND2006 (LbCas12a) in inducing targeted mutagenesis by targeting the tonoplastic monosaccharide transporter1 (TMT1) and dihydroflavonol-4-reductase 1 (DFR1) genes in 41B cells. Knockout of DFR1 gene altered flavonoid accumulation in dfr1 mutant cells. Heat treatment (34℃) improved the editing efficiencies of CRISPR/LbCas12a system, and the editing efficiencies of TMT1-crRNA1 and TMT1-crRNA2 increased from 35.3% to 44.6% and 29.9% to 37.3% after heat treatment, respectively. Moreover, the sequences of crRNAs were found to be predominant factor affecting editing efficiencies irrespective of the positions within the crRNA array designed for multiplex genome editing. In addition, genome editing with truncated crRNAs (trucrRNAs) showed that trucrRNAs with 20 nt guide sequences were as effective as original crRNAs with 24 nt guides in generating targeted mutagenesis, whereas trucrRNAs with shorter regions of target complementarity ≤ 18 nt in length may not induce detectable mutations in 41B cells. All these results provide evidence for further applications of CRISPR/LbCas12a system in grapevine as a powerful tool for genome engineering.

Simultaneous editing of two DMR6 genes in grapevine results in reduced susceptibility to downy mildew

The reduction of pesticide treatments is of paramount importance for the sustainability of viticulture, and it can be achieved through a combination of strategies, including the cultivation of vines (Vitis vinifera) that are resistant or tolerant to diseases such as downy mildew (DM). In many crops, the knock-out of Downy Mildew Resistant 6 (DMR6) proved successful in controlling DM-resistance, but the effect of mutations in DMR6 genes is not yet known in grapevine. Today, gene editing serves crop improvement with small and specific mutations while maintaining the genetic background of commercially important clones. Moreover, recent technological advances allowed to produce non-transgenic grapevine clones by regeneration of protoplasts edited with the CRISPR/Cas9 ribonucleoprotein. This approach may revolutionize the production of new grapevine varieties and clones, but it requires knowledge about the targets and the impact of editing on plant phenotype and fitness in different cultivars. In this work we generated single and double knock-out mutants by editing DMR6 susceptibility (S) genes using CRISPR/Cas9, and showed that only the combined mutations in VviDMR6-1 and VviDMR6-2 are effective in reducing susceptibility to DM in two table-grape cultivars by increasing the levels of endogenous salicylic acid. Therefore, editing both genes may be necessary for effective DM control in real-world agricultural settings, which could potentially lead to unwanted phenotypes. Additional research, including trials conducted in experimental vineyards, is required to gain a deeper understanding of DMR6-based resistance.

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 fluorescent 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 fluorescence. 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.