中文摘要：

用保存的不同泡桐无性系染病和健康组培苗为试材,对染病苗、机械损伤、嫁接接种和健康组培苗组织中H2O2及过氧化物酶的变化进行研究。用DAB组织染色方法对H2O2组织定位结果显示,在未损伤情况下多数染病泡桐苗和健康苗H2O2积累皆较少。机械损伤后,病与健苗皆出现H2O2过量积累,其中健苗强于病苗。在维管束部位,重症苗POD活性最强,轻症苗次之,无症和健康苗活性较低;而且所有苗在脉间叶肉组织POD活性都明显低于叶脉组织。用病接穗嫁接健康泡桐砧木的早期（3天以内）似乎与损伤反应类似（包括POD和H2O2产生）;6天后损伤反应减弱。嫁接接种成功的组合至20天,在嫁接接口处仍维持高的H2O2释放和强POD活性,并且砧木主茎和部分叶片出现系统性POD活性增强和H2O2积累。采用KI/淀粉试剂对H2O2组织定位结果显示：在健株主茎切片中皮层和髓细胞表面、木质部成熟导管管壁有较强的H2O2释放;而病株的相应部位产生量较少。在健康切片测定液中加入病主茎横切片可诱导健康切片H2O2积累量增加。用不同浓度的H2O2处理染病泡桐丛枝茎段外植体1h,在25～100mmol·L-1浓度范围内能明显缓解组培苗丛枝症状。抗坏血酸和低通气环境处理也有减轻病苗丛枝症状的作用。不同泡桐品系在活性氧代谢上的差异与其对植原体的抗性存在密切关系。

英文摘要：

Changes of hydrogen peroxide（H2O2） as well as peroxidase（POD） in the tissues of diseased,healthy,mechanical wounded and phytoplasma graft-transmitted tissue-cultured plantlets of different paulownia clones were investigated using histochemical methods.H2O2 localization by DAB staining method showed that the H2O2 did not significantly accumulated in both diseased and healthy plantlets of intact plants.After wounding treatment,both diseased and healthy tissues induced H2O2 accumulation,and the H2O2 in healthy tissues was more than the diseased ones.POD activity in the vascular bundles of severe diseased plants was highest,followed by that of plants with light symptoms,and then asymptomatic and uninfected plantlets.Mesophyllous tissues was lower POD activity than the veins.At the early stage（within 3 days） of graft-inoculation by means of inserting infected scion onto healthy stock,changes in the POD activity and H2O2 content had similar pattern as the mechanical wounding reaction,and these effects became weaker 6 days later after graft inoculation.The sustaining H2O2 content and high POD activity were detected at the graft union site as well as in the stock in 20 days post graft inoculation using infected scion which appeared witches-broom symptom.Moreover,the systematic induction of H2O2 and POD was also detected in the distal parts of main stem or veins of some leaves.H2O2 localization by means of KI/starch assay revealed that more H2O2 was found in the cell surface of cortex and pith as well as on the wall of conduct tube of xylem in the healthy section and less H2O2 was found in the corresponding tissues of diseased plants.When the diseased stem segments were treated with different concentration of H2O2 for 1 hour and then in vitro cultured on MS medium,it was demonstrated that the H2O2 in 25 to 100 mmol·L-1 concentrations could obviously relieve symptom on the cultured explants.Ascorbate acid and lowly aerating culture conditions also suppressed symptom development.Certain paulownia clones show