Characterization of Pisum sativum and Vicia faba microsymbionts in Morocco and definition of symbiovar viciae in Rhizobium acidisoli.

In this work, we analyzed the diversity of seventy-six bacteria isolated from Pea and faba bean nodules in two regions of Morocco. The molecular diversity was realized using the analysis of the sequences of 16S rRNA and six housekeeping genes (recA, glnII, atpD, dnaK, rpoB and gyrB) and two symbiotic genes (nodA and nodC). The phylogeny of the 16S rRNA gene sequences revealed that all strains belong to the genus Rhizobium, being related to the type strains of R. leguminosarum, R. laguerreae, R. indigoferae, R. anhuiense and R. acidisoli. The housekeeping genes phylogenies showed that some strains formed a subclade distinct from the rhizobial species that usually nodulate Vicia faba and Pisum sativum which are closely related to R. acidisoli FH23 with sequence similarity of 98.3%. Analysis of the PGPR activities of the different isolates showed that the strains related to R. laguerreae were able to solubilize phosphates and to produce siderophores and auxin phytohormone. However, R. acidisoli strain F40D2 was unable to solubilize phosphates although they produce siderophores and IAA. The phylogenetic analysis of the nodA and nodC sequences showed that all isolated strains were closely related with the strains of symbiovar viciae. The nodulation tests confirmed the ability to nodulate V. faba and P. sativum but not Cicer arietinum or Phaseolus vulgaris. Hence, in Morocco P. sativum is nodulated by R. laguerreae; whereas V. faba is nodulated by R. laguerreae and the symbiovar viciae of R. acidisoli which has been not previously described in this species.

Missbah El Idrissi M ，Lamin H ，Bouhnik O ，Lamrabet M ，Alami S ，Jabrone Y ，Bennis M ，Bedmar EJ ，Abdelmoumen H ... -  《-》

Genetic diversity and phylogeny of indigenous rhizobia nodulating faba bean (Vicia faba L.) in Greece.

The genetic diversity and phylogeny of fast-growing rhizobia isolated from root nodules of Vicia faba grown in different geographical regions of Greece were assessed. Although Rhizobium leguminosarum sv. viciae is the most common symbiont of Vicia spp. in European soils, there is no available information on native rhizobia nodulating faba bean in Greece. Seventy bacterial strains were isolated and grouped into sixteen distinct profiles based on BOX-PCR fingerprinting. The phylogenetic affiliation was further defined by sequence analysis of the rrs and multilocus sequence analysis (MLSA) of three housekeeping genes (recA, atpD and gyrB). Fifty-eight isolates were affiliated with recently described genospecies gsF-2, represented by R. laguerreae FB206T, whereas six isolates were closely related to gsB and two isolates might belong to gsA. Two isolates assigned to R. hidalgonense and another two non-nodulating strains could not be assigned to any validly defined species and possibly belong to a new rhizobial lineage. Interestingly, R. laguerreae strains were commonly found at all sampling sites, suggesting that they could be the main symbionts of faba beans in Greek soils. According to the phylogenies of two symbiosis-related genes (nodC and nifH), all nodulating isolates belonged to symbiovar (sv.) viciae harboring four distinct nodC gene haplotypes and they were grouped into two clades together with strains assigned to R. laguerreae and genospecies of R. leguminosarum isolated from other countries and continents. This is the first report that R. hidalgonense strains belong to sv. viciae. No correlation was observed between the nodC haplotypes, geographic origin and chromosomal background of the isolates in the study.

Efstathiadou E ，Savvas D ，Tampakaki AP 《-》

Vicia faba L. in the Bejaia region of Algeria is nodulated by Rhizobium leguminosarum sv. viciae, Rhizobium laguerreae and two new genospecies.

Fifty-eight rhizobial strains were isolated from root nodules of Vicia faba cv. Equina and Vicia faba cv. Minor by the host-trapping method in soils collected from eleven sites in Bejaia, Eastern Algeria. Eleven genotypic groups were distinguished based on the combined PCR/RFLP of 16S rRNA, 16S-23S rRNA intergenic spacer and symbiotic (nodC and nodD-F) genes and further confirmed by multilocus sequence analysis (MLSA) of three housekeeping genes (recA, atpD and rpoB), the 16S rRNA gene and the nodulation genes nodC and nodD. Of the 11 genotypes, 5 were dominant and 2 were the most represented. Most of the strains shared high nodD gene sequence similarity with Rhizobium leguminosarum sv. viciae; their nodC sequences were similar to both Rhizobium leguminosarum and Rhizobium laguerreae. Sequence analyses of the 16S-23S rRNA intergenic spacer showed that all the new strains were phylogenetically related to those described from Vicia sativa and V. faba in several African, European, American and Asian countries, with which they form a group related to Rhizobium leguminosarum. Phylogenetic analysis based on MLSA of 16S rRNA, recA, atpD and rpoB genes allowed the affiliations of strain AM11R to Rhizobium leguminosarum sv. viciae and of strains EB1 and ES8 to Rhizobium laguerreae. In addition, two separate clades with <97% similarity may represent two novel genospecies within the genus Rhizobium.

Belhadi D ，de Lajudie P ，Ramdani N ，Le Roux C ，Boulila F ，Tisseyre P ，Boulila A ，Benguedouar A ，Kaci Y ，Laguerre G ... -  《-》

Rhizobium anhuiense sp. nov., isolated from effective nodules of Vicia faba and Pisum sativum.

Zhang YJ ，Zheng WT ，Everall I ，Young JPW ，Zhang XX ，Tian CF ，Sui XH ，Wang ET ，Chen WX ... -  《-》

Phylogenetic study of rhizobia nodulating pea (Pisum sativum) isolated from different geographic locations in Tunisia.

Nodulated Pisum sativum plants showed the presence of native rhizobia in 16 out of 23 soil samples collected especially in northern and central Tunisia. A total of 130 bacterial strains were selected and three different ribotypes were revealed after PCR-RFLP analysis. Sequence analyses of rrs and four housekeeping genes (recA, atpD, dnaK and glnII) assigned 35 isolates to Rhizobium laguerreae, R. ruizarguesonis, Agrobacterium radiobacter, Ensifer meliloti and two putative genospecies. R. laguerreae was the most dominant species nodulating P. sativum with 63%. The isolates 21PS7 and 21PS15 were assigned to R. ruizarguesonis, and this is the first report of this species in Tunisia. Two putative new lineages were identified, since strains 25PS6, 10PS4 and 12PS15 clustered distinctly from known rhizobia species but within the R. leguminosarum complex (Rlc) with the most closely related species being R. indicum with 96.4% sequence identity. Similarly, strains 16PS2, 3PS9 and 3PS18 showed 97.4% and 97.6% similarity with R. sophorae and R. laguerreae, respectively. Based on 16S-23S intergenic spacer (IGS) fingerprinting, there was no clear association between the strains and their geographic locations. According to nodC and nodA phylogenies, strains of Rlc species and, interestingly, strain 8PS18 identified as E. meliloti, harbored the symbiotic genes of symbiovar viciae and clustered in two different clades showing heterogeneity within the symbiovar. All these strains nodulated and fixed nitrogen with pea plants. However, the strains belonging to A. radiobacter and the two remaining strains of E. meliloti were unable to nodulate P. sativum, suggesting that they were non-symbiotic strains. The results of this study further suggest that the Tunisian Rhizobium community is more diverse than previously reported.

Ilahi H ，Hsouna J ，Ellouze W ，Gritli T ，Chihaoui SA ，Barhoumi F ，Najib Elfeddy M ，Bachkouel S ，Ouahmane L ，Tambong JT ，Mnasri B ... -  《-》