Abstract

Eight (8) strains of rhizobia from Pigeon pea (Cajanus cajan) were isolated and identified based on their physiological and biochemical characteristics using standard methods. Five (5) of the isolates (KCC1 to KCC5) were subjected to partial 16S rDNA gene sequencing for phylogenetic analysis. Genetic diversity was investigated using restriction patterns produced by amplified rDNA restriction analysis (ARDRA) and were placed into different clusters. They were identified asEnsifer sinorhizobium hence named as Ensifer spp. KCC1 to KCC4. KCC5 is placed in Ensifer fredii clade. Nodulation and nitrogen fixing abilities of the isolates were confirmed by amplification of nodC and nifH genes. All of them showed indole-3-acetic acid production and phosphate solubilization activity. Only two isolates (KCC2 and KCC5) produced siderophore on CAS medium and showed strong antagonistic effect against Fusarium udum. None of the isolates produced cyanogen. The study showed that there is a considerable homogeneity amongst C. cajan root nodule isolates and can be exploited for plant growth promotion of C. cajan with effective antagonism against F. udum.

Key words: Diversity, Ensifer (Sinorhizobium) spp., pigeon pea (Cajanus cajan).

Abbreviation

Abbreviations: PGPR, Plant growth promoting rhizobacteria; IAA, indole-3-acetic acid; YEMA, yeast extract mannitol agar; EDTA, ethylenediamine tetra acetic acid;PCR-RFLP, polymerase chain reaction-restriction fragment length polymorphism;  NCBI,  national center for biotechnology information; CAS, Chrome-azurol S; PDA,potato dextrose agar; HAB, Hoffer’s alkaline broth; GPA, glucose peptone agar;ARDRA, amplified rDNA restriction analysis; PGP, plant growth-promoting; DGGE,denaturing gradient gel electrophoresis; LCOs, lipochito-oligosaccharides.