| With the rapid development of turfgrass industry in our country, more and more attentions are being paid to the genetic transformation of tall fescue (Festuca arundinacea Schreb.). Tall fescue, which belongs to the family of Gramineae, is an important turfgrass in the world. Tall fescue plays an important role in beautifying the environment and building recreational sports ground; therefore, planting tall fescue is beneficial to society, ecology and environment.Osmotic stresses, such as drought, low-temperature and high salinity, are major factors in hindering tall fescue growth and productivity. To save water, to fully utilize high salinity soil, and to further expand the application of tall fescue, it is necessary to make an osmotic stress-tolerance tall fescue by transgenic method. At present, the microprojectile bombardment method is widely used in the genetic engineering improvement of tall fescue.The establishment of regeneration system for tall fescue is the foundation for its transformation. In this paper, the establishment of tall fescue regeneration and transformation system was studied. (1) In order to establish a tissue culture system for tall fescue, different ways of seeds treatment were done to investigate their effects on the germination and pollution of seeds, and the results showed that the optimum method for the sterilization of tall fescue seeds is to soak the seeds for 1-3 h in sterile water and 30 s in 70% alcohol, wash them 5 times with sterile water, then sterilize them for 20 min in 50% sodium hypochlorite and wash them 6 times with sterile water. Using this sterilization method, the ratio of germination is 80%, while that of pollution is 0%. (2) The lower plumular axes of tall fescue seedling were inoculated on the MS mediums with different 2,4-D concentration to induce calli, and the results indicated that 10 mg/L 2,4-D was the optimum concentration on calli induction of tall fescue. (3) The embryogenic calli were inoculated on MS+ 6-BA 1 mg/L+IAA 0.1 mg/L mediums with different phosphinothricin concentration to screen calli, and the results showed that the best phosphinothricin screening concentration on calli was 2 mg/L.A mutant form of Vigna aconitifolia -pyrroline-5-carboxylate synthetase (P5CS-F129A) gene was transferred into calli of tall fescue by microprojectile bombardment. Fifty six transgenic plants were obtained through phosphinothricin screening and PCR analysis. The content of proline in transgenic plants was 31 ~83 % higher than that in control plants. Furthermore, the transgenic plants were more tolerant to drought stress by analyzing the drought-resistance physiological indexes. In addition, the transgenic plants were more tolerant to 2 mg/L phosphinothricin compared to control plants.Arabidopsis CBF4 gene, which belongs to CBF family of transcription factors, is up-regulated by drought stress. In our experiment, CBF4 was cloned into pGreen0229 vector under the drive of RD29A inducible promoter, and the plasmid (pGreen0229-RD29A-CBF4-DHA) contained a phosphinothricin resistance selectable marker. Then the plasmid was induced into calli of tall fescue by microprojectile bombardment. Four transgenic plants were obtained by PCR analysis.The AtNHXl gene encodes a Na+/H+ antiporter, which is the key enzyme to transport Na+ into the vacuole to avert the deleterious effects of Na+ in the cytosol, it maintains the Na+ balance in cells and improves the salt-tolerance of plants. In our experiment, AtNHXl was cloned into pGreen0229 vector under the drive of CaMV35S constitutive promoter, and the plasmid (pGreen0229-35S-NHXl-DHA) contained a phosphinothricin resistance selectable marker. Then the plasmid was induced into calli of tall fescue by microprojectile bombardment. Three transgenic plants were obtained. PCR analysis indicated that AtNHXl and bar genes were integrated into the genomes of transgenic plants.
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