Instituto de Florestas, Universidade Federal Rural do Rio de Janeiro, Rodovia BR 465, km 7, s/n, Zona Rural, Seropedica - RJ, 23890-000, Brazil.
Laboratório de Leguminosas Florestais, EMBRAPA, Centro Nacional de Pesquisa de Agrobiologia, Rodovia BR 465, km 7, s/n, Ecologia, Seropedica - RJ, 23891-000, Brazil.
FEMS Microbiol Ecol. 2019 Aug 1;95(8). doi: 10.1093/femsec/fiz109.
Mimosa caesalpiniifolia Benth. is a legume native to the semi-arid region of Brazil, in the Northeast. Its successful adaptation to other locations, such as the Atlantic Forest in the Southeast region, may be related to its ability to establish symbiosis with nitrogen-fixing bacteria, especially β-rhizobia of the genus Paraburkholderia. The objective of this work was to determine whether M. caesalpiniifolia adapted to bacterial symbionts in locals where it was introduced. Bacteria were recovered from nodules of M. caesalpiniifolia and characterized at the genetic level by BOX-PCR and sequencing of the 16S rRNA, recA, nifH, and nodC genes. Their symbiotic effectiveness was assessed under axenic conditions. M. caesalpiniifolia nodulated mainly with Paraburkholderia sabiae and a few strains of Rhizobium in the Southeast. On the other hand, the symbionts found in the Northeast were, predominantly, Paraburkholderia diazotrophica. Regardless of its origin, P. diazotrophica promoted a superior accumulation of plant biomass than other bacterial species. The results presented here demonstrate the ability of M. caesalpiniifolia to adapt to bacterial populations outside its location of origin, and indicate that, in this case, the symbiotic effectiveness was associated with the taxonomical classification of the strains.
金合欢（Mimosa caesalpiniifolia Benth.）是一种豆科植物，原产于巴西东北部的半干旱地区。它成功地适应了其他地区，如东南部的大西洋森林，可能与其与固氮细菌（特别是类芽胞杆菌属的β-根瘤菌）建立共生关系的能力有关。本工作的目的是确定金合欢是否适应了引入地的细菌共生体。从金合欢的根瘤中回收细菌，并通过 BOX-PCR 和 16S rRNA、recA、nifH 和 nodC 基因测序进行遗传水平的表征。在无菌条件下评估它们的共生有效性。金合欢在东南部主要与类芽胞杆菌属的萨氏固氮菌（Paraburkholderia sabiae）和少数根瘤菌菌株共生，而在东北部发现的共生体则主要是类芽胞杆菌属的脱氮副球菌（Paraburkholderia diazotrophica）。无论其起源如何，P. diazotrophica 都能促进植物生物量的更好积累，优于其他细菌种类。本研究结果表明，金合欢能够适应其起源地以外的细菌种群，并且表明在这种情况下，共生有效性与菌株的分类学分类有关。
