甘薯块根内生固氮菌的分离鉴定和系统发育分析

Isolation, identification and phylogenetic analysis of endophytic nitrogen-fixing bacteria from sweet potato tuberous root

  • 摘要: 【目的】对甘薯块根内生固氮菌进行分子鉴定和多样性分析,并分析其菌群结构,为深入研究甘薯内生固氮菌的应用提供理论参考。【方法】以鄂薯11和鄂薯17为试验材料,采用无氮培养基筛选获得2个甘薯品种块根的内生固氮菌,根据16S rDNA基因序列分析对分离的内生固氮菌进行分类鉴定;进一步扩增nifH基因片段验证固氮菌;依据Shannon多样性指数、菌株相对分离率和相似性指数对甘薯块根内生固氮菌的菌群分布及多样性进行分析,并比较内生固氮菌菌群差异。【结果】从鄂薯11和鄂薯17块根中总共分离得到80株内生固氮菌,归属为1门1纲1目1科2属,包括普里斯特氏菌属(Priestia)和芽孢杆菌属(Bacillus),相对分离率分别为51.25%和48.75%;普里斯特氏菌属在鄂薯11和鄂薯17块根的相对分离率分别为51.11%和51.43%,芽孢杆菌属在鄂薯11和鄂薯17块根的相对分离率分别为48.89%和48.57%,2个甘薯品种块根中内生固氮菌的相对分离率变化差异小。2个甘薯品种块根内生固氮菌总Shannon指数为0.6929,总均匀度指数为0.4803。鄂薯11和鄂薯17间的相似性指数为1,2个甘薯品种块根中的内生固氮菌属相同。系统发育进化树显示,从鄂薯11和鄂薯17中分离得到的内生固氮菌遗传多样性较低。【结论】从鄂薯11和鄂薯17块根中分离鉴定出80株内生固氮菌,归属于普里斯特氏菌属和芽孢杆菌属,2个品种间的内生固氮菌菌群构成无明显差异。

     

    Abstract: 【Objective】 The purpose of the study was to molecularly identify and analyze the diversity of endophytic nitrogen-fixing bacteria in tuberous roots of sweet potato, and to analyze their flora structure, so as to provide theoretical reference for further research on the application of endophytic nitrogen-fixing bacteria in sweet potato.【Method】 Using Eshu 11 and Eshu 17 as experimental materials, the endophytic nitrogen-fixing bacteria obtained from the tuberous roots of two sweet potato varieties were screened by nitrogen free medium, and the isolated endophytic nitrogen-fixing bacteria were classified and identified according to 16S rDNA gene sequence analysis. The nifH gene fragment was further amplified to verify the nitrogen-fixing bacteria. According to Shannon diversity index, relative isolation rate and similarity index of strains, the distribution and diversity of endophytic nitrogen-fixing bacteria in sweet potato tuberous roots were analyzed, and the differences in endophytic nitrogen-fixing bacterial flora were compared.【Result】 A total of 80 endophytic nitrogenfixing bacteria were isolated from the tuberous roots of Eshu 11 and Eshu 17, which belonged to 1 phylum, 1 class, 1 order, 1 family and 2 genera, including Priestia and Bacillus, with relative isolation rates of 51.25% and 48.75% respectively. The relative isolation rates of Pristeria in tuberous roots of Eshu 11 and Eshu 17 were 51.11% and 51.43% respectively, and the relative isolation rates of Bacillus in tuberous roots of Eshu 11 and Eshu 17 were 48.89% and 48.57% respectively. There was small difference in the relative isolation rate of endophytic nitrogen-fixing bacteria in the tuberous roots of the two sweet potato varieties. The total Shannon index of endophytic nitrogen-fixing bacteria in the tuberous roots of the two sweet potato varieties was 0.6929, and the total evenness index was 0.4803. The similarity index between Eshu 11 and Eshu 17 was 1, and the endophytic nitrogen-fixing bacteria in the tuberous roots of the two sweet potato varieties were of the same genera. The phylogenetic tree showed that the genetic diversity of endophytic nitrogen-fixing bacteria isolated from Eshu 11 and Eshu 17 was low.【Conclusion】 Eighty strains of endophytic nitrogen-fixing bacteria are isolated and identified from Eshu 11 and Eshu 17. The obtained endophytic nitrogen-fixing bacteria belong to Priestia and Bacillus. There is no obvious difference in the composition of endophytic nitrogen-fixing bacteria between the two varieties.

     

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