Pink Peace’rose was used to study the optimum conditions for transferring the SeNHX1 gene into the callus. The results showed that the optimal medium was MS+2,4-D 5.0 mg·L-1 + TDZ 0.5 mg·L-1. Agrobacterium tumefaciens-mediated transformation was able to take the target gene into callus and the blue spots were found. The optimum conditions for the transient expression of gusA gene are as following: bacterium density of OD was 0.5, infection time was 20 min, culture time was 3 days. Adding 100 μmol·L-1 AS, the frequency of transient expression of GUS gene was the highest, which reached about 85% in present study.
The tissue-cultured seedlings of tree peony ‘Wulong Pengsheng’ were used to study the effects of different plant growth regulators, culture methods, and holdfast on rooting. The morphological structure change during rooting was also observed using the method of paraffin section. The result showed that the best combination of plant growth regulators for rooting was IBA 3.0 mg·L-1 + NAA 0.6 mg·L-1. The treatment under the temperature of 4℃ for ten days was benefit to rooting, and the rate could reach 75.67%. It was identified that the adventitious root primordia of shoot in vitro originated from the vascular cambium cells, especially, the cross areas of cambium and pith ray and they started to differentiate at the 5th day and lasted to the 12th day. If the shoots were cultured in the root inducing medium for 12 days, it would lead to not only descend of rooting rate, but also showing callus of stem base, and leaf senescent. However, if they were transferred into the medium without hormone in time, the root primordial protruded the epidermis and developed normally after 5 days’ culture.