摘要
具有特殊生境的内生固氮菌,对改善植物营养、增强植物抗逆性及群落稳定性具有重要作用,是一类潜力巨大、尚待开发的微生物资源。以新疆3种典型荒漠灌木多枝柽柳(Tamarix ramosissima)、黑果枸杞(Lycium ruthenicum)、盐穗木(Halostachys caspica)为材料,从根和枝条组织中分离筛选获得137个内生固氮菌菌株,采用16SrDNA PCR-RFLP、16SrDNA序列测定、BOXAIR-PCR指纹图谱、nifH PCR-RFLP等方法分析其遗传多样性及系统发育关系。结果表明:分离菌株经16SrDNA PCR-RFLP酶切图谱聚类划分为9个遗传类型。序列测定和系统发育分析显示,代表菌株分属于拉恩氏菌属(Rahnella)、假单胞菌属(Pseudomonas)、泛菌属(Pantoea)、芽孢杆菌属(Bacillus)、寡养单胞菌属(Stenotrophomonas)和申氏杆菌属(Shinella),其中Rahnella为优势种群。一个测定菌株的16SrDNA序列同源性低于97%,提示可能为一个潜在的新种。BOXAIR-PCR分析优势种群的基因组结构特征,获得12种指纹图谱类型,显示出该种群具有丰富的基因组多样性。nifH PCR-RFLP分析分离内生固氮菌菌株固氮酶基因nifH的分子多态性,将其划分为3种基因型,体现了nifH具有高度保守性,同时在不同固氮微生物种群和菌株间也存在一定的多样性。研究结果丰富了固氮微生物物种资源库和基因库,对于内生固氮菌资源的保护和利用奠定了科学基础。
Endophytic diazotrophic bacteria inhabiting special ecological niche can provide benefits to the host plants such as improving nutrient supply , enhancing tolerance to stresses and maintaining community stability, so the potential areas for its practical application need to be explored. In this study, the genetic diversity and phylogeny of one hundred and thirty seven endophytic diazotrophic bacteria strains which were isolated from three typical desert shrubs, Tamarix ramosissima, Lycium ruthenicum and Halostachys caspic in arid zone of Xinjiang were studied by the methods of 16SrDNA PCR-RFLP, 16SrDNA sequencing, BOXAIR-PCR fingerprinting, nifH PCR-RFLP.The isolates were clustered into nine genotypes based on the restriction digest patterns of 16SrDNA PCR-RFLP with the enzymes MspⅠ, HaeⅢ, HinfⅠ, HhaⅠ, respectively, and the representatives of each genotype were randomly chosen for the determination of 16SrDNA sequence. The phylogenetic analysis revealed that the isolates were affiliated to six genera, consisting of Rahnella, Pseudomonas, Pantoea, Bacillus, Stenotrophomonas, Shinella, and dominant isolates were related to Rahnella. In addition, one isolate XJ-F6 showed less affiliation with known taxa (〈97% sequence similarity) and may represent a new species. The strains in Rahnella were divided into 12 genotypes with BOX-PCR genomic fingerprinting analysis, which indicated that the tested strains had a great diversity at genomic level. nifH PCR-RFLP analysis indicated that there were three genetypes among all of the strains, which revealed highly conservative characteristic of nitrogenase gene (nifH). There was a certain amount of diversity between different nitrogen-fixing microbial populations and strains. This research work enriched the diversity of endophytic diazotrophs,and establish a found for their potetential application and protaction.
出处
《中国沙漠》
CSCD
北大核心
2014年第2期472-480,共9页
Journal of Desert Research
基金
国家自然科学基金项目(31060089
41261066)资助