Comparison Of Salt-Resistance Abilities And Preliminary Research Of Genetic Transformation For Four Poplar Species

Poplar,which belongs to genus Populus,is an important plant of great economic value, and varies significantly in salt tolerance among difference species.Study of the ability of salt-tolerance in poplar and breeding of a new poplar species with high salt-tolerance property by genetic engineering contributes significantly to the development and utilization of the arability of saline-alkali soil.By comparing the salt tolerance of four poplar species including Populus deltoride×(P. therstina×P.nigra),Populus pseudo-cathayana×P.deltodides Barry CV.'Shan Hai Guan', Populus.simonii×P.euphratica and P.×euramericana "108",the most salt-tolerant species was screened,and their mechanism of salt tolerance were investigated.At the same time, using the leaves and stems as explants,adventitious buds regeneration systems for Populus deltoride×(p.therstina×P.nigra),Populus pseudo-cathayana×P.deltodides Barry CV. 'Shan Hai Guan' and P.×euramericana "108" were established.Then the genetic transformation system of Populus pseudo-cathayana×P.deltodides Barry CV.'Shan Hai Guan' was optimized.(1) Four poplar species were subjected to salinity treatments in pots grown condition. Several physiological parameters including biomass,photosynthetic parameters,chlorophyll content,the relative conductivity,MDA content,SOD activity,free proline content,the root activity and the K⁺ and Na⁺ content of the roots and leaves were measured in this work,and the results displayed that four poplars suffered different injury when the salinity concentration increased.The Populus deltoride×(P.therstina×P.nigra) was the salt-sensitive species, which was fiercely injured by 50mmol/L NaCl treatment;Populus pseudo-cathayana×P. deltodides Barry CV.'Shan Hai Guan' was hurt with 100mmol/L NaCl stress,which was moderately salt-tolerant variety:The most salt-tolerant poplar was Populus.simonii×P.euphratica.followed by P.×euramericana "108",which were salt-tolerant species and injured under the 150mmol/L NaCl treatment.So the order of the salt-tolerant ability was Populus.simonii×P.euphratica＞P.×euramericana "108"＞Populus pseudo-cathavana×P. deltodides Barry CV.'Shan Hai Guan'＞Populus deltoride×(P.therstina×P.nigra).(2) Adventitious buds regeneration systems were established via leaf and stem explants. The optimal medium for leaves regeneration of Populus pseudo-cathayana×P.deltodides Barry CV.'Shan Hai Guan' was MS medium supplemented with 0.5mg/L 6-BA and 0.1 mg/L NAA,but the adventitious buds which were induced from stems were serious vitrification; The leaves regeneration of Populus deltoride×(P.therstina×P.nigra) and P.×euramericana "108" were MS medium supplemented with 0.75mg/L 6-BA and 0.1 mg/L NAA,and the stems regeneration were MS medium supplemented with 0.25 mg/L 6-BA and 0.1 mg/L NAA. The MS medium supplemented with 0.2 mg/L 6-BA and 0.1 mg/L NAA was the subculture medium for three poplars.The roots of three species were induced and prolonged in the 1/2MS medium supplemented with 0.05 mg/L IBA.The regeneration of Populus.Simonii×p.euphratica was difficult.In the process of regeneration,the leaf browning was serious and the adventitious buds which were induced from stems were serious verifications.(3) The lethal concentration of kanamycin for the leaves regeneration of Populus pseudo-cathayana×P.deltodides Barry CV.'Shan Hai Guan' was 10 mg/L.The effective protocol of Populus pseudo-cathayana×p.deltodides Barry CV.'Shan Hai Guan' was investigated by transient GUS expression assay,and the result showed that using Agrobacterium GV3101 with non pre-cultured leaf-explants,the OD₆₀₀ of bacterium concentration was 0.4～0.6,10 min inoculation and co-culture medium supplemented with 200μmol/L AS,the transient GUS expression of inoculated explants presented the highest activity via fluorescence quantification method.