Fifty endophytic bacteria recovered from surface sterilized root nodules of chickpea (Cicer arietinum L.) grown in Ethiopia were authenticated using three chickpea cultivars (Natoli, ICC-4918 and ICC-5003). These isolates were characterized based on morphological and phenotypic traits. The test isolates were divided into two: bacteria nodulating chickpea (27 isolates, Group I] and endophytic non-nodulating bacteria (23 isolates, Group II]. Twenty isolates from Group I were able to re-infect and form symbiosis with two chickpea cultivars, while the remaining seven isolates re-infected only one chickpea cultivar. The result demonstrated that: a number of the tested isolates were able to produce siderophore, showed variations in terms of their resistance to different antibiotics, grew at pH ranging between 5 and 9.5, tolerated salt concentration as high as 2.5% and grew at a temperature as high as 40ºC, indicating the existence of a wide physiological diversity among themselves. Dendrogram construction indicated the existence of four clusters when 78% similarity level was used as cut-off point. Such diversity among the tested isolates showed the presence of diverse rhizobial and non-rhizobial isolates within chickpea nodules. Further investigation aimed at identifying the types of endophytic bacteria, their invading mechanism, and varietal preferences for nodule formation is recommended.
Key words: BNF, Chickpea, Endophytic, Mesorhizobium, non-nodulating, rhizobia.
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