Optimization of protoplast isolation,transformation and its application in sugarcane (Saccharum spontaneum L.)

Sugarcane is a prominent source of sugar and ethanol production.Genetic analysis for trait improvement of sugarcane is greatly hindered by its complex genome,long breeding cycle,and recalcitrance to genetic transformation.The protoplast-based transient transformation system is a versatile and convenient tool for in vivo functional gene analysis;however,quick and effective transformation systems are still lacking for sugarcane.Here,we developed an efficient protoplast-based transformation system by optimizing conditions of protoplasts isolation and PEG-mediated transformation in S.spontaneum.The yield of viable protoplasts was approximately 1.26×107 per gram of leaf material,and the transformation efficiency of 80.19%could be achieved under the optimized condition.Furthermore,using this approach,the nuclear localization of an ABI5-like bZIPs transcription factor was validated,and the promoter activity of several putative DNase I hypersensitive sites(DHSs)was assessed.The results indicated this system can be conveniently applied to protein subcellular localization and promoter activity assays.A highly efficient S.spontaneum mesophyll cell protoplast isolation and transient transformation method was developed,and it shall be suitable for in vivo functional gene analysis in sugarcane.

Isolation of protoplast from callus of Populus euphratica and H^+ fluxes across plasma membrane under NaCl stress

We used callus of Populus euphratica Olive to isolate protoplasts, and IT fluxes across plasma membrane were investigated. The concentration of enzymes for protoplast isolation, e.g. cellulase, pectolyase, macerozyme, hemicellulase, and sorbitol content, incubation time were systemically studied. High yield and viability of protoplast was achieved after 6-8 hours incubation of P. euphratica callus in enzyme solution containing 1.5% （w：v） cellulase R-10, 0.1% （w：v） pectolyase Y-23, 0.2% （w：v） macerozyme R-10, 0.05% （w：v） hemicellulase and 0.75M）.80 mol·L^-1 sorbitol. Non-invasively ion selective microelectrode technique was used to access proton fluxes in the absence and presence of NaCl （20 mmol.L-1）. Salt-induced transient net IT effiux was observed in the plasma membrane ofP. euphratica cells. The shift of IT flux response to NaC1 shock and the relevance to salt tolerance were discussed.

Rice Protoplasts Isolated Directly from Mature-Embryo-Derived Calli

Mature-embryo-derived calli or japonica rice (Oryza sativa L)Taipei 309 were used for replicated protoplast isolation experiments. Six out of nine callus lines produced protoplasts with satisractory yield of 5. 20×106～8. 96× 106 protoplasts/g FW(fresh weight).The remaining three callus lines Initiated from seeds of cryopreserved- callus-derived plants had rooty calli, resulting in low yield or protoplasts and a large number or isolated banana- shape intact cells. Viability or protoplasts ranged 87.46% ～94.15%.The average size or Protoplasts was 207. 49～379. 04μm2 in different callus lines.Comparitive experiments were also carried out using both calli and suspension culture cells for protoplast isolation. The results demonstrated that protoplast isolation of calli was a substantially simplified and reliable method for preparing rice protoplasts.

Plant regeneration of protoplasts isolated from suspension cells derived from leaf blale of Oryza sative

We used the leaf blade of rice (cultivars were Nonghu 6, Sugeng 2, Huyou 2 and Hanfeng) as initial material for protoplast culture, and a great number of regenerated plants were obtained. Rice seeds were sterilized and germinated. The immature leaves were cut into 3-5 mm pieces when the third or forth leaf appeared. Leaf pieces were inoculated on MS medium with 2,4-D 4 mg/1, NAA 2mg/1 and IAA Img/1. After 2 wk culture, calli were induced and subcultured once or twice for multiplication. 3-5 g calli were transferred to the modified MS liquid medium with 2,4-D 2 mg/1 and KT 0.5mg/1 for suspension culture. Embryogenic cell suspension was established after 2 mo culture. The effect of the growth period of suspension cells on the

Nitraria sibirica cell suspension culture:establishment,characterization and application

Nitraria sibirica Pall. is a shrub that grows in saline-alkali soil and has traditional medicinal value and potential commercial value. The objectives of this study include induction and multiplication of callus, establishment of a suspension cell line, and isolation of protoplasts from cell suspensions. Murashige and Skoog (MS) medium was used for callus induction from mature seeds of N. sibirica. Seed-derived calluses were further multiplied on MS medium augmented with 0.5 mg L-1 6-benzylaminopurine (6-BA) and 1.0 mg L-1 2,4-dichlorophenoxy (2,4-D) acetic acid. Suspension cultures of N. sibirica were initiated by transferring friable calli to the same liquid multiplication medium. Characterization of the suspension culture was assessed based on fresh mass, dry mass, cell viability and pH value of the culture. A typical growth curve was observed after inoculating 1.5 g of callus in 40 mL liquid medium, including a lag phase, an exponential growth phase, a stationary phase, and a negative acceleration phase. The effect of factors such as pre-plasmolysis, enzyme combination, enzymolysis time and mannitol concentration, on the isolation of cell-derived protoplasts were evaluated to determine the usefulness of suspension cultures. The maximum yield (9.79 x 10(6) cells/g) and highest viability (79.97%) of protoplast were reached when approximately 1 g of cell suspension (cultured for 6 days) was inoculated for 12 h in cell and protoplast washing solution made of 0.8 mol L-1 mannitol mixture solution, cellulose onozuka R-10 2% (w/v), hemicellulose 0.2%, macerozyme R-10 1%, and pectolyase Y-23 0.5%. Protoplast yield was significantly influenced by pre-plasmolysis and cellulose onozuka R-10 (P < 0.05).

Qu-2,a robust poplar suspension cell line for molecular biology

Populus spp.have long been used as model woody plant species for molecular biology research.However,tissues of poplar are often recalcitrant to experimental procedures for molecular studies.We generated a hormone autotrophic poplar suspension cell line from a hybrid of Populus alba×P.berolinensis‘Yinzhong’,named Qu-2.Qu-2 cells are suitable as a model biological system for studying woody plants.Qu-2 cells have many advantages over suspension cell lines derived so far from any other woody plants.Qu-2 cells are very easy to cultivate and can grow on several common plant culture media without the addition of any plant hormone.They show exceptionally high growth rates,reaching an approximately 150-fold increase in biomass after one week of culturing.Another important unique characteristic of Qu-2 cells is that they can be cryopreserved and readily reactivated.Qu-2 cells are suitable for molecular manipulations such as protoplast production,transient transformation,and RNA-seq analysis.Therefore,Qu-2 cells have the great potential to be an excellent model cell line in tree molecular biological research,ranging from physiology to gene function.The Qu-2 cells will be made available to the plant community for research.