Polymorphism of Core and Symbiotically Specialized Genes in the Polytypic Species of Nodule Bacteria

• Published in: Russian journal of genetics Vol. 59; no. 12; pp. 1401 - 1404
• Main Authors: Provorov, N. A., Kimeklis, A. K., Karasev, E. S., Khosid, S., Onishchuk, O. P., Kurchak, O. N., Andronov, E. E.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-12-2023
• Subjects: Animal Genetics and Genomics; Biomedical and Life Sciences; Biomedicine; Human Genetics; Microbial Genetics and Genomics; Short Communications; evolution of symbiosis; phylogenetic congruence and transfer of genes; nucleotide polymorphism; nodule bacteria (rhizobia)
• ISSN: 1022-7954; 1608-3369
• DOI: 10.1134/S1022795423120086

The polytypic species of nodule bacteria
Rhizobium leguminosarum
(includes biovars
viciae
and
trifolii
) and
Neorhizobium galegae
(biovars
orientalis
and
officinalis
) differ in the nucleotide polymorphism of housekeeping genes (
hkg
) and of symbiotically specialized genes (
sym
) that control the formation of N
2
-fixing nodules in leguminous plants. In
R. leguminosarum
,
p
-distance values for
sym
genes are higher than for
hkg
genes in strains from the same and from different biovars. In
N. galegae
, differences between biovars in
sym
genes are higher than in
hkg
genes, while within biovars, polymorphism in
sym
genes is lower than in
hkg
genes. Coefficients of biovar differentiation for both groups of genes are higher in
N. galegae
than in
R. leguminosarum
, possibly reflecting the spatial isolation of
N. galegae
biovars. In these species of rhizobia, the phylogenetic congruence of
sym
and
hkg
genes is more pronounced in
N. galegae
than in
R. leguminosarum
. This difference indicates an active transfer of
sym
genes in
R. leguminosarum
populations possibly representing an important factor of the deep diversification for symbiotic traits in this rhizobia species.