Molecular diversity of berseem (Trifolium alexandrinum L.) rhizobia isolated from Haryana soil

Total of forty rhizobia were isolated from nodule samples of berseem crop from farmers ’fields representing 17 villages of Haryana state, India. All the isolates were Gram-negative small rods and authenticated as rhizobia by plant infectivity test. Twenty nine rhizobial isolates on the basis of good nodulation characteristics were further selected for molecular diversity study. The amplified PCR product of genomic DNA of all the 29 rhizobia was digested with HaeIII restriction enzyme which resulted in polymorphic bands. Dendrogram based on RFLP of 16S rDNA profiles showed that all the 29 isolates were distributed in two major groups with different subgroups. A total of 7 biotypes were formed at 80% level of similarity by considering each cluster as rhizobial biotype, and out of these, two biotypes (1^st and 5^th) were found to be most prevalent in all the three districts studied. So, the rhizobia belonging to these two biotypes may be used as biofertilizer in these three districts. Moreover, isolates from same nodule were not 100% similar. It indicated that considerable diversity was present among berseem rhizobial isolates.