Biodiversity of Rhizobia That Nodulate Melilotus indicus L. in Egyptian Soils

Abstract

HE OBJECTIVES of this work were to describe the biodiversity …. and the phylogeny of the selected rhizobial isolates nodulating wild legume Melilotus indicus L. (M. indicus) from 14 different Egyptian soils. These isolates were characterized morphologically and physiologically on the basis of their tolerance to NaCl and pH. Furthermore, the DNA of each rhizobial isolate was analyzed by rep-PCR amplification fingerprinting using REP, ERIC and BOX A1R primers. Thirty seven rhizobial isolates were obtained from the root nodules of M. indicus. These isolates didn`t absorb Congo-red (CR) when incubated in dark; grew poorly, or not at all, on peptone glucose agar medium containing bromocresol purple (BCP) and acidified the medium suggesting fast-growing rhizobia. Five isolates tolerated NaCl up to 7%. Rhizobial isolates showed a wide diversity in their pH tolerance. Moreover, PCR with REP and ERIC primer pairs yielded multiple distinct DNA products for each isolate of size ranged from approximately 177 to 3773 bp and 200 to 2921 bp, respectively. BOX A1R primer did not reveal any polymorphism for the isolates. We can conclude that rhizobia isolated from M. indicus from Egyptian soils are both phenotypically and genetically diverse.