Reconnoitering the capabilities of nodule endophytic Pantoea dispersa for improved nodulation and grain yield of chickpea (Cicer arietinum L.).

Microorganisms belonging to root and soil provide a wide range of services and benefits to the plant by promoting plant growth and controlling phytopathogens. This study aimed to isolate endophytic bacteria from the root nodules of chickpea (Cicer arietinum L.) and determine their potential in improving plant growth. A total of nineteen different bacterial morphotypes were isolated from root nodules of chickpea and characterized in vitro for plant growth promotion abilities. All bacterial isolates were able to produce indole acetic acid at varying levels, out of which MCA19 was screened as the most efficient indole acetic acid producer (10.25 µg mL-1). MCA8, MCA9, MCA10, MCA11, MCA16, MCA17 and MCA19 were positive for phosphate solubilization, out of which MCA9 was best phosphate solubilizer (18.8 µg mL-1). All bacterial strains showed varying ability to grow on nitrogen-free media. Hydrogen cyanide, pectinase, and cellulase production ability were also observed in isolates, in which MCA9, MCA12, MCA17 and MCA19 were found best. Based on in vitro testing, five isolates MCA2, MCA9, MCA11, MCA17 and MCA19 were selected for further studies. Bacterial isolates MCA9, MCA11, MCA17 and MCA19 were identified by 16S rRNA gene sequence analysis as Pantoea dispersa while MCA2 as Rhizobium pusense. This is the first report on the existence of Pantoea dispersa in the root nodules of chickpea. In pot experiment, a maximum increase of 30% was recorded in plant dry weight upon the application of MCA19. Under field conditions, bacterial isolates, MCA2, MCA11 and MCA19 significantly enhanced nodulation and yield parameters of chickpea, compared to control. Pantoea dispersa MCA19 displayed the highest plant growth-promoting potential by increasing 38% grain yield. Our results indicate that Pantoea dispersa MCA19 is a promising biofertilizer for future applications.