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【目的】分离鉴定同株罹病柑橘黄龙病植株不同显症状况组织的内生细菌,寻找与黄龙病菌[‘Candidatus Liberibacter asiaticus’(Ca.Las)]相互作用的优势菌株。【方法】利用基于16S rDNA的PCRDGGE(Denaturing gradient gel electrophoresis)分析同一柑橘黄龙病罹病植株的显症和未显症组织内生细菌多样性,并用定量PCR方法,对果、枝、叶3种组织黄龙病菌、优势菌株及细菌总数进行检测。【结果】结果显示显症和无症组织所带黄龙病菌差异很大,显症部位病菌量明显高于无症部位。分析显症和无症组织内生细菌DGGE图谱显示,同一组织内生菌群结构基本相同;对图谱中17条明显条带回收克隆测序,发现其中8个条带均属于沙雷氏菌属(Serratia),占总条带数的47.06%。序列分析显示这8条序列为粘质沙雷氏菌(Serratia marcescens)不同的菌株(序列相似性为99.63%)。定量分析各差异显症部位单位组织内的粘质沙雷氏菌和细菌总数,发现相同部位的总细菌量差异不显著,但粘质沙雷氏菌与黄龙病菌的量呈负相关。【结论】柑橘黄龙病病株中,各部位所带病菌量不均匀,是否显症与组织内柑橘黄龙病菌的量呈正相关,内生菌群总量与显症无相关性,但粘质沙雷氏菌与黄龙病菌的量呈负相关。粘质沙雷氏菌与黄龙病菌在韧皮部细胞内增殖过程中的相互作用值得深入研究。
【Objective】 The objective of this study was to isolate and identify endophytic bacteria in different tissues of diseased plants of Citrus Huanglongbing and to find out the dominant strains for their interaction with Candidatus Liberibacter asiaticus (Ca.Las). 【Method】 Denaturing gradient gel electrophoresis (PCR-DGGE) based on 16S rDNA was used to analyze the pathogenic bacteria in the diseased plants of the same Citrus Huanglongbing. The endophytic bacteria diversity in the diseased plants of the same Citrus Huanglongbing were analyzed. Huanglong bacteria, the dominant bacteria and the total number of bacteria for testing. 【Results】 The results showed that there were significant differences between the pathogenic and pathogenic tissues of the pathogenic bacteria, and the pathogenic bacteria in the disease area were significantly higher than the asymptomatic sites. Analysis of disease and endometriosis DGGE analysis of asymptomatic tissues showed that the same organization endophytic flora structure is basically the same; on the map of 17 clear bands recovery cloning and sequencing, found that eight of which belonged to Serratia ( Serratia), accounting for 47.06% of the total number of bands. Sequence analysis showed that the eight sequences were different strains of Serratia marcescens (sequence similarity of 99.63%). Quantitative analysis of the total number of S. marcestrins and bacteria in the tissues of each symptom showed that there was no significant difference in the total amount of bacteria in the same part, but there was a negative correlation between the amount of Serratia marcescens and the amount of Huanglongbing. 【Conclusion】 There was a positive correlation between the pathogenic bacteria and the amount of citrus Huanglongbing in the citrus Huanglongbing diseased plants. The total amount of endophytic flora was not correlated with the disease, Rex bacteria and the amount of yellow dragon’s disease was negatively correlated. The interaction between Serratia marcescens and the pathogen Huangphylla in the proliferation of phloem cells deserves further study.