Protoplast Yield Research Articles

Direct leaf-peeling method for areca protoplasts: a simple and efficient system for protoplast isolation and transformation in areca palm (Areca catechu)

BackgroundAreca palm (Areca catechu) is a woody perennial plant of both economical and medicinal importance grown in tropical and subtropical climates. Yet, the molecular biology study of areca palm is extremely impeded by its unavailability of a transformation method. An efficient protoplast isolation and transformation system could be highly desirable to overcome this barrier.ResultsHere, we described a simple and efficient method for protoplast isolation and transformation from the perennial plant areca palm. A high yield of protoplasts (2.5 × 107 protoplasts per gram of fresh leaf tissues) was obtained from the fresh light green leaflet from the newly-emerged leaf digested overnight in the enzyme solution [2% (w/v) cellulase R10, 0.5% (w/v) macerozyme R10, 0.7 M mannitol, 10 mM CaCl2, 20 mM KCl, 20 mM MES and 0.1% (w/v) BSA, pH 5.7] by the direct leaf-peeling method. The isolated areca protoplasts maintain viability of 86.6% and have been successfully transformed with a green fluorescent protein (GFP)-tagged plasmid (pGreen0029-GFP, 6.0 kb) via the polyethylene glycol (PEG)-mediated transformation. Moreover, the mannitol concentration (optimal: 0.7 M) was determined as a key factor affecting areca protoplast isolation. We also demonstrated that the optimal density of areca protoplast for efficient transformation was at 1.0–1.5 × 106 cells/ml. With the optimization of transformation parameters, we have achieved a relatively high transformation efficiency of nearly 50%.ConclusionWe have established the first efficient protocol for the high-yield isolation and transformation of areca palm protoplasts. This method shall be applied in various biological studies of areca palm, such as gene function analysis, genome editing, protein trafficking and localization and protein–protein interaction. In addition, the protoplast system offers a great genetic transformation approach for the woody perennial plant-areca palm. Moreover, the established platform may be applied in protoplast isolation and transformation for other important species in the palm family, including oil palm and coconut.

Establishment of an efficient cotton root protoplast isolation protocol suitable for single-cell RNA sequencing and transient gene expression analysis

BackgroundCotton has tremendous economic value worldwide; however, its allopolyploid nature and time-consuming transformation methods have hampered the development of cotton functional genomics. The protoplast system has proven to be an important and versatile tool for functional genomics, tissue-specific marker gene identification, tracking developmental trajectories, and genome editing in plants. Nevertheless, the isolation of abundant viable protoplasts suitable for single-cell RNA sequencing (scRNA-seq) and genome editing remains a challenge in cotton.ResultsWe established an efficient transient gene expression system using protoplasts isolated from cotton taproots. The system enables the isolation of large numbers of viable protoplasts and uses an optimized PEG-mediated transfection protocol. The highest yield (3.55 × 105/g) and viability (93.3%) of protoplasts were obtained from cotton roots grown in hydroponics for 72 h. The protoplasts isolated were suitable for scRNA-seq. The highest transfection efficiency (80%) was achieved when protoplasts were isolated as described above and transfected with 20 μg of plasmid for 20 min in a solution containing 200 mM Ca2+. Our protoplast-based transient expression system is suitable for various applications, including validation the efficiency of CRISPR vectors, protein subcellular localization analysis, and protein–protein interaction studies.ConclusionsThe protoplast isolation and transfection protocol developed in this study is stable, versatile, and time-saving. It will accelerate functional genomics and molecular breeding in cotton.

Evaluation and Improvement of Protocols for Ganoderma boninense Protoplast Isolation and Regeneration

Ganoderma boninense is the causal agent of basal stem rot (BSR) disease of oil palm. The BSR disease reduces oil palm yield by up to 80% of the average oil yield. Attempts to control the disease caused by this fungus in the field showed varying levels of success and cases of infection increased from year to year. Hence, the development of new efficient methods to control the spread of this fungus should be commenced promptly. To ensure a better strategy is created, more thorough research on the method deploy by this fungus to infect the host at the molecular level need to be carried out first. However, the major limitation in endeavoring into the functional analysis of virulence genes related to the pathogenicity of this fungus was hampered by the unavailability of established methods for protoplast isolation with a high regeneration rate to be used in the genetic manipulation analysis. Thus, in this paper, we report an efficient protocol for protoplast isolation and regeneration in G. boninense and successfully used the isolated protoplasts in PEG-mediated transformation analysis. A large quantity of protoplast was obtained using the protocol that utilizes the following parameters: 3 to 4-day-old mycelia, treated with 1% lysing enzyme and 0.02% Driselase, incubated at 30 °C in an osmotic medium containing 0.6 M mannitol at pH 5.8 for 2 h. The highest protoplast yield was in the range of 8.95 × 109 to 3.12 × 1010 cells/mL per 5 g of mycelia used. The regeneration rate ranged from 9.03% to 22.55%, depending on the regeneration media used. By using 5 µg of vector to transform into 1.0 × 107 protoplast/mL, around 3 – 10 mitotically stable putative transformants were successfully obtained and verified via PCR. This protocol will find useful applications in genetic studies to enhance insight into this poorly characterized and understood phytopathogen.

Isolation, purification and PEG-mediated transient expression of mesophyll protoplasts in Camellia oleifera

BackgroundCamellia oleifera (C. oleifera) is a woody edible oil crop of great economic importance. Because of the lack of modern biotechnology research, C. oleifera faces huge challenges in both breeding and basic research. The protoplast and transient transformation system plays an important role in biological breeding, plant regeneration and somatic cell fusion. The objective of this present study was to develop a highly efficient protocol for isolating and purifying mesophyll protoplasts and transient transformation of C. oleifera. Several critical factors for mesophyll protoplast isolation from C. oleifera, including starting material (leaf age), pretreatment, enzymatic treatment (type of enzyme, concentration and digestion time), osmotic pressure and purification were optimized. Then the factors affecting the transient transformation rate of mesophyll protoplasts such as PEG molecular weights, PEG4000 concentration, plasmid concentration and incubation time were explored.ResultsThe in vitro grown seedlings of C. oleifera ‘Huashuo’ were treated in the dark for 24 h, then the 1st to 2nd true leaves were picked and vacuumed at − 0.07 MPa for 20 min. The maximum yield (3.5 × 107/g·FW) and viability (90.9%) of protoplast were reached when the 1st to 2nd true leaves were digested in the enzymatic solution containing1.5% (w/v) Cellulase R-10, 0.5% (w/v) Macerozyme R-10 and 0.25% (w/v) Snailase and 0.4 M mannitol for 10 h. Moreover, the protoplast isolation method was also applicable to the other two cultivars, the protoplast yield for ‘TXP14’ and ‘DP47’ was 1.1 × 107/g·FW and 2.6 × 107/g·FW, the protoplast viability for ‘TXP14’ and ‘DP47’ was 90.0% and 88.2%. The purification effect was the best when using W buffer as a cleaning agent by centrifugal precipitation. The maximum transfection efficiency (70.6%) was obtained with the incubation of the protoplasts with 15 µg plasmid and 40% PEG4000 for 20 min.ConclusionIn summary, a simple and efficient system for isolation and transient transformation of C. oleifera mesophyll protoplast is proposed, which is of great significance in various aspects of C. oleifera research, including the study of somatic cell fusion, genome editing, protein function, signal transduction, transcriptional regulation and multi-omics analyses.

Оптимизация методики получения протопластов кукурузы и их нативность после электропорации

We optimizes the composition and concentration of the enzymes, the time for enzymatic treatment and the volume of the enzyme mixture. We also optimized the concentration osmotic of agent, the centrifugation mode, and filter pore size for protoplasts isolating from epidermal cells of maize roots (Zea mays L.) of the Brown Marker (BM) line. It was found that 150 minutes is the optimal time for 150 mg root tissue maceration. The yield of intact protoplasts was ~ 4.4 ± 0.2 × 105 cells/mL at the following concentrations of enzymes and osmotic stabilizer: cellulase – 17,4, pectolase – 1.2, hemicellulase – 0.07, D-mannitol – 9.3%. The the concentration of protoplasts was to 23 times higher (p < 0.05) in 800 μl, compared with 200 μl of the enzyme mixture with equal concentrations of enzymes and osmotic stabilizer. It was found that filtration of 800 μl protoplast suspension through a filter with a pore size of 15 × 15 microns increases the yield of protoplasts up to 3.3 times, compared with a filter with a pore size of 15×39. Fractional centrifugation without preliminary filtration of the solution and the flotation method did not produce an increase in the yield of protoplasts. The residual number and protoplast wholeness after ~ 20 hours at +3 °C incubation was evaluated. The protoplast number decreased up to 2 times (p < 0.05) after electroporation.

Plant regeneration from leaf mesophyll derived protoplasts of cassava (Manihot esculenta Crantz).

A high yield of isolated protoplast and reliable regeneration system are prerequisite for successful somatic hybridization and genome editing research. However, reproducible plant regeneration from protoplasts remains a bottleneck for many crops, including cassava. We evaluated several factors that influence isolation of viable protoplasts form leaf mesophyll, induction of embryogenic calli, and regeneration of plants in three cassava cultivars; Muchericheri, TMS60444 and Karibuni. A relatively higher protoplast yield was obtained with enzyme mixture containing 5 g/L Macerozyme and 10 g/L cellulase. Muchericheri recorded relatively higher protoplast yield of 20.50±0.50×106 whereas TMS60444 (10.25±0.25×106) had the least protoplast yield in 10 g/L cellulase and 4 g/L cellulase. Freshly isolated protoplast cells were plated on callus induction medium (CIM) solid medium containing MS basal salt, 60 g/L D-glucose, 30 g/L sucrose, B5 vitamins, 100 mg/L myo-inositol, 0.5 mg/L copper sulphate, 100 mg/L casein hydrolysate, 4.55 g/L mannitol, 0.1 g/L MES, 10 mg/L picloram and 3 g/L gelrite to induce protoplast growth and development. The three cultivars reached colony formation but no further development was observed in this culture method. Protoplast growth and development was further evaluated in suspension culture using varying cell densities (1, 2 and 3× 105 p/mL). Development with highest number of minicalli was observed in cell density of 3× 105 p/mL. Minicalli obtained were cultured on CIM supplemented with 10mg/L picloram. Callus induction was observed in all cell densities with the cultivars. Highest somatic embryogenesis was observed in 2× 105 p/ml while no somatic embryogenesis was observed in cell density of 1×105 p/mL. Somatic embryos were matured in EMM medium supplemented with 1 mg/L BAP, 0.02 mg/L NAA and 1.5 mg/L GA3 then germinated in hormone free medium for plant regeneration. This protocol which used simple mixture of commercial enzymes is highly reproducible and can be applied in biotechnology research on cassava.

Establishment of a Protoplasts-Based Transient Expression System in Banana (Musa spp.)

The breeding of triploid banana cultivars with improved traits, such as yield and disease resistance, remains a major challenge for breeders. One reason is that the molecular study and functional gene analysis in bananas fall behind due to the difficulties of its genetic manipulation. The plant protoplast-based transient transformation has been documented and widely used as a versatile and convenient system for functional gene analysis in many plant species. However, an efficient high-quality protoplast isolation and transformation system is still lacking for bananas. Here, we established an efficient protoplast isolation and transformation method for bananas by selecting proper source materials, optimizing conditions for enzymatic hydrolysis and PEG-mediated transfection. We found the best source materials for banana protoplasts’ isolation are young suckers, which give a yield of protoplasts ranging from 2.5 × 106 to 10.1 × 107 g−1 fresh weight after 5 to 6 h of enzymolysis. The yield is sufficient for most assays that have been established in protoplasts-based systems, such as protein subcellular localization and protein interaction assays. Moreover, using the established transient gene expression system in banana protoplasts, we validated the subcellular localization of Arabidopsis VESICLE SORTING RECEPTOR 1 (VSR1) and the protein self-interaction of Arabidopsis CNGC20 on the cell membrane. The results indicated this system works well and could be routinely used for the functional characterization of banana genes.

DNA Free CRISPR/DCAS9 Based Transcriptional Activation System for UGT76G1 Gene in Stevia rebaudiana Bertoni Protoplasts.

The UDP-glycosyltransferase 76G1 (UGT76G1) is responsible for the conversion of stevioside to rebaudioside A. Four single guide RNAs (sgRNAs) were designed from the UGT76G1 proximal promoter region of stevia by using the online-based tool, benchling. The dCas9 fused with VP64 as a transcriptional activation domain (TAD) was produced and purified for the formation of ribonucleoproteins (RNPs) by mixing with the in vitro transcribed sgRNAs. Protoplast yield was the highest from leaf mesophyll of in vitro grown stevia plantlets (3.16 × 106/g of FW) using ES5 (1.25% cellulase R-10 and 0.75% macerozyme R-10). The RNPs were delivered into the isolated protoplasts through the Polyethylene glycol (PEG)-mediated transfection method. The highest endogenous activation of the UGT76G1 gene was detected at 27.51-fold after 24 h of transfection with RNP30 consisting of CRISPR/dCas9-TAD with sgRNA30 and a similar activation level was obtained using RNP18, RNP33, and RNP34, produced using sgRNA18, sgRNA33, and sgRNA34, respectively. Activation of UGT76G1 by RNP18 led to a significant increase in the expression of the rate-limiting enzyme UGT85C2 by 2.37-fold and there was an increasing trend in the expression of UGT85C2 using RNP30, RNP33, and RNP34. Successful application of CRISPR/dCas9-TAD RNP in activating specific genes can avoid the negative integration effects of introduced DNA in the host genome.

An improved protocol for protoplast production, culture, and whole plant regeneration of the commercial brown seaweed Undaria pinnatifida

Protoplasts (i.e., living plant cells devoid of cell wall) represent an important biotechnological tool with utility for the conduction of in vitro studies and crop improvement in economic cultivars. Undaria pinnatifida is an annual brown kelp commonly used in Asian cuisine and several industries because of its biological properties. It is one of the major seaweed cultivars used worldwide. This study establishes a simple and effective protocol for protoplast isolation, culture, and whole plant regeneration of U. pinnatifida . The results showed that high protoplast yields (2–4 × 10 7 protoplast g −1 of fresh weight) were obtained using the commercially available enzymes cellulase “Onozuka” RS (1 %) and alginate lyase (4 U mL −1 ) without any pre-treatment and with a short incubation time (2–4 h). The isolation protocol described herein presented with more effective results with meristematic explants and was superior to the protocols reported for U. pinnatifida and other brown algae. Additionally, the enzymatic mixture could be reused up to six times. Whole plant regeneration was accomplished after 3 months in culture at 20 °C using two culture media, and a mixture of antibiotics (penicillin G, streptomycin, and chloramphenicol) was added once at the beginning of the culture. Our regeneration protocol was less laborious and more cost-effective, exhibiting final plating efficiency higher than previously reported and demonstrating the potential to be used to produce up to 3 × 10 4 sporophytes g −1 of explant. The established protocol can be easily used for genetic manipulation, protoplast fusion, or micropropagation, thus enabling the expansion of the use of protoplasts in algae. • Single-step production of protoplasts from the edible seaweed Undaria pinnatifida using commercial enzymes • The reusability of the enzyme shows that the process is economically viable. • Antibiotics and temperature are key factors for protoplast survival, division and normal regeneration. • Regeneration protocol is simpler and more effective than previously reported.

A high yield method for protoplast isolation and ease detection of rol B and C genes in the hairy roots of cauliflower (Brassica oleracea L.) inoculated with Agrobacterium rhizogenes

Protoplasts represent a unique experimental system for the circulation and formation of genetically modified plants. Here, protoplasts were isolated from genetically modified hairy root tissues of Brassica oleracea L. induced by the Agrobacterium rhizogenes strain (ATCC13332). The concentration of enzyme solutions utilized for protoplast isolation was 1.5 % Cellulase YC and 0.1 % Pectolyase Y23 in 13% mannitol solution, which resulted in high efficiency of isolation within 8 hours, in which the protoplast yield was 2 x 104 cells ml-1 and the percentage of viability was 72%. Each protoplast has one nucleus with a nucleation of 48%. A polymerase chain reaction (PCR) assay verified the presence of rol B and rol C genes in hairy root tissues by detaching a single bundle of DNA replication from these roots using a specific pair of primers. The current study demonstrated that A. rhizogenes strain (ATCC13332) is a vector for the incorporation of T-DNA genes into cauliflower plants, as well as the success of the hairy roots retention of rol B and rol C genes transferred to it.

Development of a petal protoplast transfection system for Sinningia speciosa.

PremiseTransient gene expression systems are powerful tools for studying gene interactions in plant species without available or stable genetic transformation protocols. We optimized a petal protoplast transformation protocol for Sinningia speciosa, a model plant, to study the development of floral symmetry.Methods and ResultsA high yield of petal protoplasts was obtained using a 6‐h enzyme digestion in a solution of 1.5% cellulase and 0.4% macerozyme. Modest transfection efficiency (average 41.4%) was achieved. The viability of the transfected protoplasts remained at more than 90%. A fusion of green fluorescent protein and CYCLOIDEA (SsCYC), the Teosinte branched 1/Cincinnata/Proliferating cell factor transcription factor responsible for floral symmetry, was subcellularly localized inside the nuclei of the protoplasts. Transiently overexpressing SsCYC indicates the success of this system, which resulted in the predicted increased (but nonsignificant) expression of its known target RADIALIS (SsRAD1), consistent with gene network expectations.ConclusionsThe transient transfection system presented herein can be effectively used to study gene‐regulatory interactions in Gesneriaceae species.

Optimization of protocol for efficient protoplast isolation and transient gene expression in carnation

The optimal protocols for protoplast isolation and transfection in carnation cv. Scarlet were developed by optimizing the factors involved in protoplast isolation and transfection processes. The best protoplast yield and viability were achieved using 0.5 M mannitol, enzyme concentrations of 1.0% cellulase and 0.1% macerozyme, and digestion time of 8 h. In contrast, the best transfection efficiency was obtained using protoplast density of 2.5 × 105, polyethylene glycol (PEG) concentration of 20%, and transfection time of 15 min. The protocols could produce reasonable protoplast yield and transfection efficiency in other carnations. The transient expression of enhanced green fluorescent protein (eGFP) in the nucleus of the transfected protoplasts of all carnations was confirmed using PCR analysis. To our knowledge, this is the first report on transient gene expression in carnation protoplasts. This transient gene expression system could be valuable for genome editing of unwanted genes in carnations using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 technology.

Transcriptomic Variations and Network Hubs Controlling Seed Size and Weight During Maize Seed Development.

To elucidate the mechanisms underlying seed development in maize, comprehensive RNA-seq analyses were conducted on Zhengdan1002 (ZD1002), Zhengdan958 (ZD958), and their parental lines during seven seed developmental stages. We found that gene expression levels were largely nonadditive in hybrids and that cis-only or trans × cis pattern played a large role in hybrid gene regulation during seed developmental stage. Weighted gene co-expression network (WGCNA) analysis showed that 36 modules were highly correlated (r = −0.90–0.92, p < 0.05) with kernel weight, length, and width during seed development. Forty-five transcription factors and 38 ribosomal protein genes were identified as major hub genes determining seed size/weight. We also described a network hub, Auxin Response Factor 12 of maize (ZmARF12), a member of a family of transcription factor that mediate gene expression in response to auxin, potentially links auxin signal pathways, cell division, and the size of the seeds. The ZmARF12 mutant exhibited larger seed size and higher grain weight. ZmARF12 transcription was negatively associated with cell division during seed development, which was confirmed by evaluating the yield of protoplasts that isolated from the kernels of the mutant and other inbred lines. Transient knock-down of ZmARF12 in maize plants facilitated cell expansion and division, whereas transient silencing of its potential interactor ZmIAA8 impaired cell division. ZmIAA8 expression was repressed in the ZmARF12 over-expressed protoplasts. The mutant phenotype and the genetics studies presented here illustrated evidence that ZmARF12 is a cell division repressor, and potentially determines the final seed size.

Application of Protoplast Regeneration to CRISPR/Cas9 Mutagenesis in Nicotiana tabacum.

Protoplast transfection is widely used in plant research to rapidly evaluate RNA degradation, reporter assay, gene expression, subcellular localization, and protein-protein interactions. In order to successfully use protoplast transfection with the newly emerging clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) protein editing platform, high yield of protoplasts, stable transfection efficiency, and reliable regeneration protocols are necessary. The Nicotiana tabacum transient protoplast transfection and regeneration system can effectively obtain target gene mutations in regenerated plants without transgenes and is thus a very attractive technique for evaluating gene editing reagents using CRISPR/Cas-based systems. Here, we describe in detail sterilized seed germination, culture conditions, isolation of Nicotiana tabacum protoplasts from tissue culture explants, construction of a vector containing the Cas protein and sgRNA cassette, highly efficient polyethylene glycol-calcium transient transfection of plasmids delivered into protoplasts, evaluation of mutagenesis efficiency and genotype analysis from protoplasts and regenerated plants, and the regeneration conditions to obtain CRISPR-edited plants from single protoplasts.

Protoplast isolation from Dictyopteris pacifica and Scytosiphon lomentaria, using a simple commercial enzyme preparation

BackgroundProtoplasts (i.e., naked plant cells) can be used for in vitro manipulations and genetic improvement in cultivars with economic value. During the last decade, protoplast research in economic brown algae has been scarce, and it is usually hampered by the use of non-commercial enzymes or crude extracts for isolating protoplasts. Dictyopteris pacifica is part of a brown algal genus well known by its wide chemical diversity and biological properties. Scytosiphon lomentaria is an edible brown seaweed with antioxidant, antitumor, and antiviral properties. So far, there are no protoplast isolation protocols using commercial enzymes for these two economic brown algae. In this study, we obtained protoplasts from cultured samples of D. pacifica and S. lomentaria using commercially available enzymes. Additionally, we investigated the effects of Driselase inclusion and Ca-chelation pre-treatment on protoplast yields in order to optimize the conditions for protoplast preparations. ResultsProtoplasts were isolated from Dictyopteris pacifica and Scytosiphon lomentaria using the commercially available Cellulase Onozuka RS (1%) and Alginate lyase (4 U mL−1), and short incubation time (4 h). Driselase did not show significant effects on protoplast production in both species. Ca-chelation pre-treatment only increased the number of protoplasts in D. pacifica. Under optimal conditions, the protoplast yields from D. pacifica and S. lomentaria were 4.83 ± 2.08 and 74.64 ± 32.49 × 106 protoplasts g−1 fresh weight, respectively. The values obtained for S. lomentaria were 2–3 orders of magnitude higher than previously reported. ConclusionsOur results show that high protoplast yields can be obtained from D. pacifica and S. lomentaria using a simple mixture of commercial enzymes (Cellulase RS and Alginate lyase) and short incubation time (4 h). This work also represents the first report of protoplast isolation in D. pacifica. The method proposed here can help to expand protoplast technology in more brown algal species.

Efficient protocol improved the yield and viability of oil palm protoplasts isolated from in vitro leaf and mesocarp

The absence of a cell wall on the protoplast contributes to its versatility. Its flexibility for DNA manipulation and the possibility of rapid cell-based assay is desirable in the plant biotechnology field. This study was carried out to improve protoplast isolation from oil palm in vitro leaf and mesocarp tissues. The factors affecting protoplast isolation efficiency were optimized, including the protocols and enzyme composition involved, focusing on the oil palm in vitro leaf first. Incubation of oil palm leaf sample with an enzyme mixture of cellulase R-10, macerozyme R-10, driselase, and pectolyase Y-23, for 14 h has successfully produced up to 2.5 × 106 protoplasts g-1 fresh weight (FW)-1 with 95% viability. Incubation of oil palm mesocarp tissue with the optimized enzyme mixture for 2 h at static condition has also successfully produced 3.98 × 106 protoplasts g-1 FW-1 with 85% viability. Besides, it was found that increasing the sample's surface area in contact with enzyme solution by slicing the samples into narrow strips and thin layers has improved the penetration of enzymes into the tissues and enhanced the isolation efficiency. In addition, a plasmolysis step before enzymatic treatment has also improved the protoplast viability by minimizing the damage incurred during isolation. The successful isolation of protoplast from oil palm leaf and mesocarp has enabled the study of gene function and the characterization of endogenous tissue-specific promoter being carried out in vivo.

An efficient genetic manipulation protocol for dark septate endophyte Falciphora oryzae.

To investigate the protoplast preparation and transformation system of endophytic fungus Falciphora oryzae. F. oryzae strain obtained higher protoplast yield and effective transformation when treated with enzyme digestion solution containing 0.9M KCl solution and 10mgmL-1 glucanase at 30 °C with shaking at 80rpm for 2-3h. When the protoplasts were plated on a regenerations-agar medium containing 1M sucrose, the re-growth rate of protoplasts was the highest. We successfully acquired green fluorescent protein-expressing transformants by transforming the pKD6-GFP vector into protoplasts. Further, the GFP expression in fungal hyphae possessed good stability and intensity during symbiosis in rice roots. This study provided a protoplast transformation system of F. oryzae, creating opportunities for future genetic research in other endophytic fungi.

Efficient isolation and purification of tissue-specific protoplasts from tea plants (Camellia sinensis (L.) O. Kuntze)

BackgroundPlant protoplasts constitute unique single-cell systems that can be subjected to genomic, proteomic, and metabolomic analysis. An effective and sustainable method for preparing protoplasts from tea plants has yet to be established. The protoplasts were osmotically isolated, and the isolation and purification procedures were optimized. Various potential factors affecting protoplast preparation, including enzymatic composition and type, enzymatic hydrolysis duration, mannitol concentration in the enzyme solution, and iodixanol concentration, were evaluated.ResultsThe optimal conditions were 1.5% (w/v) cellulase and 0.4–0.6% (w/v) macerozyme in a solution containing 0.4 M mannitol, enzymatic hydrolysis over 10 h, and an iodixanol concentration of 65%. The highest protoplast yield was 3.27 × 106 protoplasts g−1 fresh weight. As determined through fluorescein diacetate staining, maximal cell viability was 92.94%. The isolated protoplasts were round and regularly shaped without agglomeration, and they were less than 20 μm in diameter. Differences in preparation, with regard to yield and viability in the tissues (roots, branches, and leaves), cultivars, and cultivation method, were also observed.ConclusionsIn summary, we reported on a simple, efficient method for preparing protoplasts of whole-organ tissue from tea plant. The findings are expected to contribute to the rapid development of tea plant biology.

Effect of Enzyme Treatments on Protoplast Isolation from Leaves of Vetiver (Vetiveria spp.)

Protoplast isolation is a first and important step for establishing a new plant with desired traits through protoplast fusion technology. This experiments were conducted to evaluate various concentration of enzymes and incubation time on protoplast yield and viability in two vetiver ecotypes, Kamphaeng Phet 2 (Vetiveria zizanioides Nash) and Prachuap Khiri Khan (V. nemoralis A.Camus). The results revealed that protoplast yields were significantly affected by different enzyme treatments. The highest protoplast yield (6.12x105 protoplasts/ml) and high viability (98.61%) in Kamphaeng Phet 2 was obtained through the process of cell wall digestion when treated with enzyme solution containing 0.5% (w/v) cellulase onozuka R-10 and 0.5% (w/v) macerozyme R-10 in combination. While, the optimal enzyme solution for protoplast isolation from leaves of Prachuap Khiri Khan was the combination of 1.0% (w/v) cellulase onozuka R-10 and 0.4% (w/v) macerozyme R-10, resulting in the highest yield (6.80x105 protoplasts/ml) and viability (96.56%) of protoplasts. Meanwhile, incubation time of 24 h with the optimal enzyme solution resulted in the highest protoplast yields of both ecotypes. Our findings have the potential to generate an efficient protocol to isolate the protoplast from leaves of vetiver which can be used for further research studies in protoplast culture and fusion for vetiver improvement. Keywords: Cellulase onozuka R-10, Macerozyme R-10, Protoplast isolation, Vetiver

Callus induction, suspension culture and protoplast isolation in Camellia oleifera

Camellia oleifera is a woody edible oil crop with economical importance. This study established an efficient protocol for the induction of callus, the multiplication of a suspension cell line, and the isolation and purification of protoplasts in Camellia oleifera. It is shown that the callus induction was best when anthers were treated with the hormone of 0.5 mg/L NAA (Naphthaleneacetic acid), 2.0 mg/L 2,4-D (2,4-Dichlorophenoxyacetic acid) and 0.5 mg/L 6-BA (6-Benzylaminopurine) at 4 °C for 15 days. Callus was further multiplied on MS (Murashige and Skoog) medium augmented with 5% coconut water, 2 mg/L 2,4-D, 0.5 mg/L 6-BA, pH 5.8. Though three types of induced callus transferred to the same liquid medium with the ratio of 1 g callus inoculated into 30 ml liquid medium, it was found that the suspension culture effect of loose particles callus was the best. The maximum yield (11.7 × 106/g·FW) and highest viability (95.1%) of protoplast were reached when cell suspension (cultured for 6 days) was inoculated for 14 h in enzyme solution made of 0.4 mol/L mannitol mixture solution, 1.0% (w/v) Cellulase R-10 and 1.0% (w/v) Macerozyme R-10. The study lays a foundation for future research in cell fusion and transient gene expression in Camellia oleifera.