| Platanus spp. Were popular in China as roadside trees and garden trees in many cities from the southern China northern toward the Liaoning province. The tree species of Platanus acerifolia and Platanus orintalis have 2～6 heads of fruits on per infructescence; However, the American sycamore (Platanus occidentalis L.) commonly has one head on per infructescence. Compared with the other species within the Platanus genus, American sycamore has as less as 10%～20% seeds and flying hair . So it seems more suitable to be roadside trees than the others. American sycamore is one of the important forest trees for timber products with fast growth. The gene transformation on American sycamore by gene engineering technique is an effective way to create new genetic materials of American sycamore with insect-resistance, disease-resistance. In this dissertation, two types of initial explants, shoot segments and leaves of asepsis seedlings, were taken to study American sycamore organogenesis, including adventitious buds induction. Factors have been tested for their effects on organogenesis and adventitious buds. The adventitious buds were induced successfully from the leaves of this species for the first time in the world. A high-efficient tissue culture system was established from leaf discs. This system can be used for transforming Platanus occidentalis L. by Agrobaterium tumefaciens mediated method. Nine factors affecting transformation were investigated and an effective genetic transformation system was established. This unique system provides a key platform for gene engineering and molecular breeding for Platanus occidentalis L. Top cut pruning was made on an American sycamore crown, and segments from new sprout were collected as tissue culture initial explants. We observed the effect of several factors on buds induction, such as basal medium, hormone and organic matter R. Adventitious buds were induced from shoot segment. The results indicated that as for shoot segments induction buds the optimal medium was MS+NAA0.1mg/L+BA1.0mg/L +sucrose30g/L,and DCR+NAA0.1　mg/L+6-BA　1.0mg/L+KT　0.3mg/L+ sucrose30g/L was the optimal medium for induction buds proliferation, on which induction buds grew well and coefficient of multiplication reached 6.4 times. We developed two ways to get adventitious buds to root. One was that adventitious buds were transferred on the DCR medium with 150mg/L R; The other, on the DCR medium with 60mg/L R about for 15d and then, transferred on a garniture –free DCR. By the two ways, both of the rooting percentages were up to 100%. The plant regeneration from leaf discs of Platanus occidentalis L. and the effect of various factors on its receptor system of genetic transformation were described in this dissertation. We studied the several effecting factors (on induction buds from leaf discs, such as auxin, cytokine, sucrose, dark-culture time, method of inoculation and antibiotics,). The result showed that auxin was not the major factor, but the different kind of cytokine had a significant different effect on the differentiation percentage. The differentiation percentage was significantly improved by combination of 6-BA with KT. In addition, the leaf sensitivity to antibiotic AP, Cb, Cef and Km was studied and the results revealed that the leaf sensitivity to AP was very low, Cb and Km could restrain leaf from differentiating adventitious buds, and Cef improved differentiation percentage. We also concluded that for leaf induction buds the optimal medium was MS+IBA 0.5mg/L+6-BA 1.5 mg/L+KT 0.5mg/L+sucrose 30g/L. With the discs dark-cultured for seven days and added Cef 200mg/L after having pre-cultured, the bud induction frequency, average number of buds and bud forming capacity all reach the maximum, with 100%, 5.6 and 5.6 respectively. From then established receptor system genetic transformation, nine factors affecting the transformation of American sycamore (Platanus occidentalis L.) were studied by infecting with Agrobacterium Tumefaciens LBA4404, such as pre-culture time, LBA4404 concentration, infecting time, Agrobacterium medium, bacterium liquid preparation method, AS and sucrose concentration of co-cultrue medium, pH of co-cultrue medium , co-cultrue time. We have preliminarily determined an effective system for genetic transformation. The protocol was follows: 2～3 days for pre-culture , OD600 =0.1～0.4, 5～15 minutes for infection, 2～3 days for co-culture, pH5.6, 40g/L sucrose and AS60μmol/L as co-culture medium, delay for 3 days. And then we screened the medium from which we have obtained 205 regenerated Km-resistant buds. From the second selection medium we have obtained 17 regenerated Km-resistant buds. PCR analysis on 25 regenerated Km-resistant buds showed that 12 buds were PCR positive. The result indicated that BT gene was integrated into the genome of American sycamore 12 Km-resistant buds.
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