Screening of plant growth-promoting Rhizobium tarimense from root nodules of chickpea (Cicer arietinum)

Abstract

Plant growth-promoting rhizobacteria (PGPR) are favourable bacteria that colonize the plant roots and enhance plant growth by direct and/or indirect mechanisms. This study aimed to screen rhizobial isolates of chickpea and evaluate their multiple plant growth-promoting traits. A total of twelve rhizobia-like-bacterial isolates were collected from the root nodules of chickpea (Cicer arietinum L.) from different regions of Madhya Pradesh, India, characterized by morphological, biochemical, and identified by the 16S rRNA gene sequencing. Out of twelve, one rhizobial isolate designated as RH17 was confirmed as Rhizobium tarimense by 16S rRNA gene sequencing, which showed 98% similarity with the strain PL-41. The phylogenetic study was done by using MEGA-X to confirm the identity of RH17 isolate and the nucleotide sequence of the 16S rRNA gene of RH17 isolate was submitted to the National Center for Biotechnology Information (NCBI) database under Genbank with accession number OM996100. The RH17 isolate showed multiple plant growth-promoting traits like nitrogen fixation, solubilization of phosphate (15mm), indole acetic acid (IAA) production (1µg/ml), 1-aminocyclopropane-1-carboxylate (ACC) deaminase (0.5nmol), ammonia (NH3), siderophore, hydrogen cyanide (HCN) production and antagonism against phytopathogenic fungi Fusarium oxysporum and Macrophomina phaseolina. Therefore, the present study suggests that R. tarimense (RH17) isolate can be used as PGP bacteria and a biocontrol agent to enhance the growth, productivity and yield of chickpea.