Laboratory of Biodiversity and Valorization of Arid Areas Bioresources (BVBAA) - Faculty of Sciences of Gabes, Erriadh, Zrig 6072, Tunisia.
Centro de Biotecnología y Genómica de Plantas (UPM-INIA), ETSI Agronómica, Alimentaria y de Biosistemas, Campus de Montegancedo, Universidad Politécnica de Madrid, Madrid, Spain.
Syst Appl Microbiol. 2020 Mar;43(2):126067. doi: 10.1016/j.syapm.2020.126067. Epub 2020 Jan 25.
Forty rhizobial strains were isolated from Lotus creticus, L. pusillus and Bituminaria bituminosa endemic to Tunisia, and they belonged to the Mesorhizobium and Ensifer genera based on 16S rDNA sequence phylogeny. According to the concatenated recA and glnII sequence-based phylogeny, four Bituminaria isolates Pb5, Pb12, Pb8 and Pb17 formed a monophyletic group with Mesorhizobium chacoense ICMP14587, whereas four other strains Pb1, Pb6, Pb13 and Pb15 formed two separate lineages within the Ensifer genus. Among the L. pusillus strains, Lpus9 and Lpus10 showed a 96% identical nucleotide with Ensifer meliloti CCBAU83493; whereas six other strains could belong to previously undescribed Mesorhizobium and Ensifer species. For L. creticus strains, Lcus37, Lcus39 and Lcus44 showed 98% sequence identity with Ensifer aridi JNVU TP6, and Lcus42 shared a 96% identical nucleotide with Ensifer meliloti CCBAU83493; whereas another four strains were divergent from all the described Ensifer and Mesorhizobium species. The analysis of the nodC gene-based phylogeny identified four symbiovar groups; Mesorhizobium sp. sv. anthyllidis (Lpus3 and Lpus11 from L. pusillus, Lcus43 from L. creticus), Ensifer medicae sv. meliloti (four strains from L. creticus and two strains from L. pusillus), E. meliloti sv. meliloti (four from L. creticus, four from L. pusillus and four from B. bituminosa). In addition, four B. bituminosa strains (Pb5, Pb8, Pb12, and Pb17) displayed a distinctive nodC sequence distant from those of other symbiovars described to date. According to their symbiotic gene sequences and host range, the B. bituminosa symbionts (Pb5, Pb8, Pb12 and Pb17) would represent a new symbiovar of M. chacoense for which sv. psoraleae is proposed.
从突尼斯特有的 Lotus creticus、Lotus pusillus 和 Bituminaria bituminosa 中分离出 40 株根瘤菌，根据 16S rDNA 序列系统发育分析，它们属于 Mesorhizobium 和 Ensifer 属。根据 recA 和 glnII 序列的系统发育分析，4 株 Bituminaria 分离株 Pb5、Pb12、Pb8 和 Pb17 与 Mesorhizobium chacoense ICMP14587 形成单系群，而其他 4 株 Pb1、Pb6、Pb13 和 Pb15 则在 Ensifer 属内形成两个独立的谱系。在 Lotus pusillus 菌株中，Lpus9 和 Lpus10 与 Ensifer meliloti CCBAU83493 具有 96%相同的核苷酸；而其他 6 株菌株可能属于以前未描述的 Mesorhizobium 和 Ensifer 种。对于 Lotus creticus 菌株，Lcus37、Lcus39 和 Lcus44 与 Ensifer aridi JNVU TP6 的序列同一性为 98%，而 Lcus42 与 Ensifer meliloti CCBAU83493 的核苷酸相同性为 96%；而另外 4 株菌株与所有描述的 Ensifer 和 Mesorhizobium 种均有差异。nodC 基因系统发育分析鉴定出 4 个共生型群；Mesorhizobium sp. sv. anthyllidis（Lpus3 和 Lpus11 来自 Lotus pusillus，Lcus43 来自 Lotus creticus）、Ensifer medicae sv. meliloti（来自 Lotus creticus 的 4 株菌株和来自 Lotus pusillus 的 2 株菌株）、E. meliloti sv. meliloti（来自 Lotus creticus 的 4 株菌株、来自 Lotus pusillus 的 4 株菌株和来自 Bituminaria bituminosa 的 4 株菌株）。此外，4 株 Bituminaria bituminosa 菌株（Pb5、Pb8、Pb12 和 Pb17）的 nodC 序列与迄今为止描述的其他共生型均有明显差异。根据其共生基因序列和宿主范围，Bituminaria bituminosa 的共生体（Pb5、Pb8、Pb12 和 Pb17）将代表一种新的 Mesorhizobium chacoense 共生型，建议命名为 sv. psoraleae。
