Ulrich Andreas, Zaspel Irmtraut
ZALF - Centre for Agricultural Landscape and Land Use Research, Institute of Primary Production and Microbial Ecology, Eberswalder Str. 84, D-15374 Müncheberg, Germany1.
Federal Research Centre for Forestry and Forest Products, Institute for Forest Genetics and Forest Tree Breeding, Eberswalder Chaussee 3, D-15377 Waldsieversdorf, Germany2.
Microbiology (Reading). 2000 Nov;146 ( Pt 11):2997-3005. doi: 10.1099/00221287-146-11-2997.
Lack of knowledge exists regarding the diversity of rhizobial strains nodulating black locust (Robinia pseudoacacia L.), which is a neophytic tree species widely distributed in Europe. Seventeen rhizobial strains isolated from nodules of black locust at a German location were examined by phenotypic characterization and 16S rDNA analysis. The isolates were classified in nine 16S rDNA genotypes using a set of seven endonucleases. Based on RFLP analysis and sequencing, the strains were shown to belong to the genera Mesorhizobium (76%) and Rhizobium (24%). Five genotypes were identical to the species Mesorhizobium amorphae, Mesorhizobium loti, Mesorhizobium huakuii, Rhizobium leguminosarum and Rhizobium tropici. A strong similarity between the 16S rDNA sequence of another two genotypes and M. amorphae (99.9%) as well as the Mesorhizobium strain R88b (99.8%) was found. The two remaining genotypes were classified in the genus Rhizobium, without a significant relationship at the species level. Comparing isolates nodulating Rob. pseudoacacia and Amorpha fruticosa, a parallel picture of phylogenetic diversity was detected with a range of phylogenetically different rhizobia and M. amorphae dominating. For this study, 18 rhizobial strains which had originally been isolated from a forest in Maryland where black locust is native were additionally analysed. Results revealed seven genotypes all belonging to the genus Mesorhizobium, with four genotypes identical to the isolates from the German sampling location. Whereas the genotype identical to M. amorphae dominated within the strains obtained from the German location, the dominance of a genotype identical to M. huakuii was found among the strains from the native location. Summarizing data from both locations, Rob. pseudoacacia was nodulated with various genomic species, most of which belonged to the genus Mesorhizobium. Concerning phenotypic features such as growth rate, pH tolerance or use of certain carbohydrates, most isolates corresponded to described species and genera. However, there were differences in salt tolerance between these isolates and the corresponding reference strains. Overall, the results demonstrated a high phenotypic and phylogenetic diversity of rhizobial strains nodulating Rob. pseudoacacia. This may be a characteristic of neophytic and other widely spread legumes and may contribute to the success of black locust as a pioneer tree species for the temperate zone.
关于能使刺槐（Robinia pseudoacacia L.）结瘤的根瘤菌菌株的多样性，目前仍缺乏相关认知。刺槐是一种新生物种的树木，在欧洲广泛分布。通过表型特征分析和16S rDNA分析，对从德国某地点的刺槐根瘤中分离出的17株根瘤菌菌株进行了检测。使用一组七种核酸内切酶，将这些分离株分为九个16S rDNA基因型。基于RFLP分析和测序，这些菌株被证明属于中慢生根瘤菌属（76%）和根瘤菌属（24%）。五个基因型与中慢生根瘤菌、百脉根中慢生根瘤菌、华癸中慢生根瘤菌、豌豆根瘤菌和热带根瘤菌物种相同。发现另外两个基因型的16S rDNA序列与中慢生根瘤菌（99.9%）以及中慢生根瘤菌菌株R88b（99.8%）有很强的相似性。其余两个基因型被归类于根瘤菌属，在物种水平上没有显著关系。比较使刺槐和紫穗槐结瘤的分离株，发现了系统发育多样性的平行情况，一系列系统发育不同的根瘤菌和中慢生根瘤菌占主导地位。对于本研究，还额外分析了最初从刺槐原生地马里兰州的一片森林中分离出的18株根瘤菌菌株。结果显示有七个基因型均属于中慢生根瘤菌属，其中四个基因型与来自德国采样地点的分离株相同。在从德国地点获得的菌株中，与中慢生根瘤菌相同的基因型占主导地位，而在来自原生地的菌株中，发现与华癸中慢生根瘤菌相同的基因型占主导地位。综合两个地点的数据，刺槐与各种基因组物种结瘤，其中大多数属于中慢生根瘤菌属。关于生长速率、pH耐受性或某些碳水化合物的利用等表型特征，大多数分离株与已描述的物种和属相对应。然而，这些分离株与相应参考菌株在耐盐性方面存在差异。总体而言，结果表明使刺槐结瘤的根瘤菌菌株具有高度的表型和系统发育多样性。这可能是新生物种和其他广泛传播的豆科植物的一个特征，可能有助于刺槐作为温带先锋树种的成功。
