中文摘要：

毛白杨是一种具有多种优良特性、用途广泛并有重要经济价值的杨属树种，又是农杆菌的天然寄主植物。因此，毛白杨一直是进行木本植物组培及遗传转化研究的重要对象。本研究通过比较培养基组成(Table 1)、外植体类型(Table 2)、农杆菌侵染浓度以及预培养(Table 3&4, Fig.1)和共培养条件(Table 5)等影响农杆菌转化及植株再生效率的诸多重要条件后，建立了毛白杨的农杆菌高效转化系统。实验选用毛白杨叶片为外植体，在MS + 4.0 mg/L 2,4-D + 1.0 mg/L 6-BA培养基上预培养2 d后制成叶盘，并做戳伤处理，再与5×108 Cell/mL浓度的农杆菌新鲜菌液共培养2 d，然后以MS + 4.0 mg/L 2,4-D + 1.0 mg/L 6-BA附加50 mg/L Km和1 000 mg/L AP为筛选培养基(Table 6, Fig.4) ，获得最佳转化效果。2－3周后，在叶盘周围长出许多Km抗性愈伤组织，转入分化培养基分化后，再转入生根培养基3－4周，获得完整植株(Fig.3)。经PCR扩增实验鉴定，转化愈伤组织的阳性率达到83.8％(Fig.2)。多次重复实验结果表明，该转化系统与以往的文献报道相比，其遗传转化率大大提高。抗性愈伤组织的平均转化率高达56.2%，最终得到的再生转化植株的比率达19.9%。其中，毛白杨叶盘经戳伤处理，其转化率可提高至20~40% (Table 7)。利用此转化系统?

英文摘要：

Populus tomentosa, as an important economic plant and as a natural host of Agrobacterium tumefaciens, has been used as a model plant for tissue culture and genetic transformation study of xyloghyta. In this work, several important factors influencing the efficiency of Agrobacterium-mediated transformation and regeneration of plants, such as types of explants, concentration of Agrobacterium suspension, wounding treatment on explants, conditions of pre-cultivation and co-cultivation, medium composition etc, were studied, and an Agrobacterium-mediated high frequency system was established for P. tomentosa. After pre-cultivation in the medium MSy for 48 h, the healthy sterile leaves were cut into discs, co-cultivated with suspension of A. tumefaciens LBA4404 at the concentration of 5×108 cells/mL for another 48 h, and then transferred onto the selective media containing appropriate antibiotics. The average transformation frequency of kanamysin resistant (Kmr) calli was up to 56.2%, and the ratio of the number of transgenetic plants to the number of explants was up to 19.9%. Only by wounding treatment alone, the transformation frequency was improved by 20~40%. With this transformation system, NP-1, a disease resistant gene, was successfully introduced into P. tomentosa and a lot of transgenetic plants were obtained.