Clawson ML, Caru M, Benson DR
Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269-3044, USA.
Appl Environ Microbiol. 1998 Sep;64(9):3539-43. doi: 10.1128/AEM.64.9.3539-3543.1998.
Partial 16S ribosomal DNAs (rDNAs) were PCR amplified and sequenced from Frankia strains living in root nodules of plants belonging to the families Elaeagnaceae and Rhamnaceae, including Colletia hystrix, Elaeagnus angustifolia, an unidentified Elaeagnus sp., Talguenea quinquenervia, and Trevoa trinervis. Nearly full-length 16S rDNAs were sequenced from strains of Frankia living in nodules of Ceanothus americanus, C. hystrix, Coriaria arborea, and Trevoa trinervis. Partial sequences also were obtained from Frankia strains isolated and cultured from the nodules of C. hystrix, Discaria serratifolia, D. trinervis, Retanilla ephedra, T. quinquenervia, and T. trinervis (Rhamnaceae). Comparison of these sequences and other published sequences of Frankia 16S rDNA reveals that the microsymbionts and isolated strains from the two plant families form a distinct phylogenetic clade, except for those from C. americanus. All sequences in the clade have a common 2-base deletion compared with other Frankia strains. Sequences from C. americanus nodules lack the deletion and cluster with Frankia strains infecting plants of the family Rosaceae. Published plant phylogenies (based on chloroplast rbcL sequences) group the members of the families Elaeagnaceae and Rhamnaceae together in the same clade. Thus, with the exception of C. americanus, actinorhizal plants of these families and their Frankia microsymbionts share a common symbiotic origin.
从胡颓子科和鼠李科植物根瘤中的弗兰克氏菌菌株中PCR扩增并测序了部分16S核糖体DNA（rDNA），这些植物包括多刺鼠李、沙枣、一种未鉴定的胡颓子属植物、五脉雀梅藤和三脉棱罗。从美洲蓟木、多刺鼠李、乔木马桑和三脉棱罗根瘤中的弗兰克氏菌菌株中测序了近乎全长的16S rDNA。还从从多刺鼠李、锯齿叶盘刺李、三脉盘刺李、麻黄叶类叶升麻、五脉雀梅藤和三脉棱罗（鼠李科）根瘤中分离培养的弗兰克氏菌菌株中获得了部分序列。这些序列与已发表的其他弗兰克氏菌16S rDNA序列的比较表明，除了来自美洲蓟木的菌株外，这两个植物科的微共生体和分离菌株形成了一个独特的系统发育分支。与其他弗兰克氏菌菌株相比，该分支中的所有序列都有一个共同的2碱基缺失。来自美洲蓟木根瘤的序列没有该缺失，并且与感染蔷薇科植物的弗兰克氏菌菌株聚类在一起。已发表的植物系统发育（基于叶绿体rbcL序列）将胡颓子科和鼠李科的成员归为同一分支。因此，除了美洲蓟木外，这些科的放线菌根植物及其弗兰克氏菌微共生体具有共同的共生起源。
