Department of Microbiology, College of Resource and Environment, Sichuan Agricultural University, Chengdu, 611130, China,
World J Microbiol Biotechnol. 2013 Dec;29(12):2303-15. doi: 10.1007/s11274-013-1396-z. Epub 2013 Jun 8.
Leucaena leucocephala was introduced into Panxi, Sichuan, China, in the 1980s and 1990s for afforestation and preventing water loss and soil erosion in this area. The co-introduction of rhizobial symbionts of introduced plants has drawn attention since they may influence local soil communities. We studied the phylogenetic position of the L. leucocephala isolates and assessed if the rhizobia were introduced together with the host to Panxi, Sichuan, China. The glnII and atpD genes of fifteen representative isolates were sequenced and analyzed, and applied multilocus sequence analyses in which the housekeeping genes recA, glnII and atpD were included. Furthermore, we estimated the within species diversity directly with 23S rDNA and IGS RFLP and indirectly through phenotypic analysis of forty L. leucocephala isolates. The isolates represented seven species and 38 diversified strains in the genera Ensifer, Mesorhizobium, Bradyrhizobium and Rhizobium. The within species diversity of the Ensifer isolates was large, proposing a potential to occupy novel niches. There was not conclusive evidence to show that any of the strains would have been co-introduced with L. leucocephala. On the contrary, we came to a conclusion that the possible introduction should not be inferred from sequence data alone.
银合欢（Leucaena leucocephala）于 20 世纪 80 年代和 90 年代被引入中国四川攀西地区，用于造林和防止水土流失。共生引入植物的根瘤菌共生体引起了人们的关注，因为它们可能会影响当地的土壤群落。我们研究了银合欢分离株的系统发育地位，并评估了根瘤菌是否与宿主一起被引入中国四川攀西地区。我们对 15 个代表分离株的 glnII 和 atpD 基因进行了测序和分析，并应用了包括管家基因 recA、glnII 和 atpD 的多位点序列分析。此外，我们通过对 40 株银合欢分离株的表型分析，直接利用 23S rDNA 和 IGS RFLP 以及间接利用 23S rDNA 和 IGS RFLP 来估计种内多样性。这些分离株代表了 7 个种和 38 个多样化的菌株，分别属于根瘤菌属、中慢生根瘤菌属、慢生根瘤菌属和根瘤菌属。根瘤菌属分离株的种内多样性很大，这表明它们有可能占据新的生态位。没有确凿的证据表明任何菌株与银合欢一起被引入。相反，我们得出的结论是，仅凭序列数据不能推断出可能的引入。
