Abstract

Nine soil rhizobia isolated from different field locations were subjected to RAPD analysis to study the diversity. It was found that Rhizobium isolates from Agricultural Research Station - Aliyar Nagar (ALN 7), Department of Agricultural Microbiology (SOB 1), isolates from TNAU Eastern block field No. 36 (EB 36) and Millet Breeding station field: 9 (MBS 19) were clustered together to form cluster 1 followed byRhizobium isolates Millet Breeding station field: 8 (MBS 9), isolates from the Department of Agrl. Microbiology, TNAU 14 and COG 15 belongs to cluster 2 and isolates of Cotton Breeding station field No: 9 (CBS 9) and Aliyar Nagar (ALN 2) formed the fourth cluster. Department of Agricultural Microbiology isolate, COG 15 with TNAU 14 and SOB 1 with Rhizobium ALN 7 were clustered together with more than 50 per cent similarity. Isolate from Cotton Breeding station field No: 12 (CBS 12) was found to have more divergence (>90 per cent) to make the separate cluster. The results indicated that RAPD is a very discriminative and efficient method for differentiating and studying genetic diversity of Rhizobium strains.

Key words: Rhizobium, RAPD, genetic diversity.