and molecular characterization of root nodule microsymbiont of Trigonella
foenum-graecum L. growing in different soils from Western Rajasthan,
Gaur1, N. Tak1, S. Rathi1, S. Choudhary1,2
and H.S. Gehlot1*
1BNF and Microbial
Genomics Lab., Department of Botany, UGC-Center of Advanced Study, Jai Narain
Vyas University, Jodhpur - 342 001, India
Division, Arid Forest Research Institute, Jodhpur - 342 005, India
Author E-mail: firstname.lastname@example.org
Paper received :
Revised received :
Re-revised received :
Accepted : 06.02.2018
Aim: To identify and
characterize N fixing root nodule bacteria (RNB) of Trigonella
foenum-graecum (TFG) growing in soils collected from different districts
of Western Rajasthan.
Methodology: Selected RNB
strains were characterised phenotypically and molecular phylogeny was studied
using their 16S rRNA and symbiosis-related gene sequences.
Results: The 31 selected
RNB strains formed three groups on the basis of colony characteristics. The
TFG-RNB strains showed metabolic diversity in terms of carbon utilization and
intrinsic antibiotic resistance, with few strains showing NaCl tolerance up
to 4% and growth on a wide range of pH (4-11). In 16S rRNA gene phylogeny six
(TFG22, TFG33, TFG53, TFG59, TFG64 and TFG66) selected strains clustered in a
novel clade close to type strains Ensifer medicae and Ensifer meliloti
forming two distinct 16S rRNA types. The symbiotic (nodA and nifH)
and 16S rRNA phylogenies of TFG-Ensifer strains were in congruence.
The sym genes of TFG strains have intermediate sequences diversified from
closely related E. meliloti and E. medicae which
indicates their evolution through horizontal gene transfer.
Interpretation: Nitrogen fixing
TFG-Ensifer strains isolated from Western Rajasthan are potentially
novel and showing plant growth promoting activity therefore can be used as
inoculants in agricultural fields of semi-arid regions.
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