Parker Matthew A
Department of Biological Sciences, State University of New York, Binghamton 13902, USA.
Syst Appl Microbiol. 2004 May;27(3):334-42. doi: 10.1078/0723-2020-00266.
Enzyme electrophoresis and sequencing of rRNA and dnaK genes revealed high genetic diversity among root nodule bacteria from the Costa Rican trees Andira inermis, Dalbergia retusa, Platymiscium pinnatum (Papilionoideae tribe Dalbergieae) and Lonchocarpus atropurpureus (Papilionoideae tribe Millettieae). A total of 21 distinct multilocus genotypes [ETs (electrophoretic types)] was found among the 36 isolates analyzed, and no ETs were shared in common by isolates from different legume hosts. However, three of the ETs from D. retusa were identical to Bradyrhizobium sp. isolates detected in prior studies of several other legume genera in both Costa Rica and Panama. Nearly full-length 16S rRNA sequences and partial 23S rRNA sequences confirmed that two isolates from D. retusa were highly similar or identical to Bradyrhizobium strains isolated from the legumes Erythrina and Clitoria (Papilionoideae tribe Phaseoleae) in Panama. rRNA sequences for five isolates from L. atropurpureus, P. pinnatum and A. inermis were not closely related to any currently known strains from Central America or elsewhere, but had affinities to the reference strains Bradyrhizobium japonicum USDA 110 (three isolates) or to B. elkanii USDA 76 (two isolates). A phylogenetic tree for 21 Bradyrhizobium strains based on 603 bp of the dnaK gene showed several significant conflicts with the rRNA tree, suggesting that genealogical relationships may have been altered by lateral gene transfer events.
对来自哥斯达黎加树木无刺安豆、黑黄檀、羽叶扁轴木（蝶形花亚科黄檀族）和紫花罗顿豆（蝶形花亚科崖豆族）的根瘤菌进行酶电泳以及rRNA和dnaK基因测序，结果显示其具有高度的遗传多样性。在所分析的36个分离株中，共发现了21种不同的多位点基因型[ETs（电泳类型）]，不同豆科宿主的分离株没有共同的ETs。然而，黑黄檀的三个ETs与先前在哥斯达黎加和巴拿马对其他几个豆科属的研究中检测到的慢生根瘤菌属分离株相同。近乎全长的16S rRNA序列和部分23S rRNA序列证实，黑黄檀的两个分离株与从巴拿马的刺桐属和蝶豆属（蝶形花亚科菜豆族）豆科植物中分离出的慢生根瘤菌菌株高度相似或相同。来自紫花罗顿豆、羽叶扁轴木和无刺安豆的五个分离株的rRNA序列与目前已知的中美洲或其他地区的任何菌株都没有密切关系，但与参考菌株日本慢生根瘤菌USDA 110（三个分离株）或埃氏慢生根瘤菌USDA 76（两个分离株）具有亲缘关系。基于dnaK基因603 bp构建的21个慢生根瘤菌菌株的系统发育树与rRNA树存在几个显著冲突，这表明谱系关系可能已因横向基因转移事件而改变。
