Genetic Diversity and Symbiotic Efficiency of Nodulating Rhizobia Isolated from Root Nodules of Faba Bean in One Field

Abstract

Thirty-one nodulating rhizobium strains were collected from root nodules of spring and winter type faba bean cultivars grown in micro ecoarea, i.e. the same field in Chengdu plain, China. The symbiotic efficiency and phylogeny of these strains were studied. Effectively nitrogen fixing strains were isolated from both winter type and spring type cultivars. Based on phylogenetic analysis of 16S rRNA gene and concatenated sequence of atpD, glnII and recA genes, the isolates were assigned as Rhizobium anhuiense and a potential new Rhizobium species. The isolates were diverse on symbiosis related gene level, carrying five, four and three variants of nifH, nodC and nodD, respectively. Strains carrying similar gene combinations were trapped by both winter and spring cultivars, disagreeing with the specificity of symbiotic genotypes to reported earlier faba bean ecotypes.

Assessment of Genetic Diversity and Symbiotic Efficiency of Selected Rhizobia Strains Nodulating Lentil (Lens culinaris Medik.)

“…The rpoB gene showed the highest variability rate, expressed by Transition/Transversion index, genetic distance range and pairwise distance mean index, compared to recA and gyrB genes within the studied population. This finding is supported by the nature of each gene with rpoB containing hyper-variable zones allowing for rapid identification of bacteria at a sub-species level [ 44 ] whereas recA and gyrB genes, widely used for interspecies rhizobia classification [ 45 , 46 ] are considered very conserved genes and useful in discriminating between species [ 47 ]. Hence, the rpoB gene remains the best marker to be used for studying the relationships between closely related strains [ 29 ].…”

“…The strain 1159N52 and strain 1159N41 showed the lowest similarity among the strains with 95 and 96% similarities to R. leguminosarum , respectively. Many studies considered 97% as the threshold for defining a new genospecies [ 46 , 51 ]. However, the difference in the utilized concatenated genes in the MLSA approach may impact the reliability of the threshold considering the independent evolutions of the genes.…”

Genetically diverse lentil- and faba bean-nodulating rhizobia are present in soils across Central and Southern Ethiopia

“…According to previous studies, faba bean rhizobia were taxonomically classified as Rhizobium leguminosarum (Allen 1981), R. fabae (Tian et al 2008), R. anhuiense (Zhang et al 2015;Chen et al 2018) and R. laguerreae (Saidi et al 2014). R. leguminosarum species was also commonly identified as symbionts of lentil and field pea (Tegegn 2006;Rashid et al 2012;Zou et al 2016). The population composition of the rhizobial species might be different depending on geographic regions; in China, R. anhuiense was found to be the main faba bean symbiont among rhizobial species identified in the Panxi region (Chen et al 2018).…”

Genetic and symbiotic characterization of rhizobia nodulating legumes in a mining area in southeast Brazil

“…With the advances in molecular techniques, genetic characterization of these strains has become increasingly accessible for taxonomic classification as well as for corroborating the functionality of the strains related to symbiotic N 2 fixation (Zou et al, 2016). Within this context, the aim of this study was to i) authenticate and verify the symbiotic efficiency of 18 strains inoculated into seedlings of their respective host species in a greenhouse, and evaluate the possible morpho-physiological benefits in these species; ii) genetically characterize these strains by sequencing of housekeeping genes (atpD and gyrB) and comparing them phylogenetically with sequences of type strains; iii) analyze the presence of specific genes related to nitrogen fixation (nifH) and nodulation (nodC and nodD) to obtain strains with biotechnological potential for the recommendation as inoculants.…”