Molecular Identification and Phylogenetic Relationships of Rhizobial Strains Nodulating Some Leguminous Crops

Abstract

Isolation, molecular identification and phylogenetic relationships of Rhizobial isolates nodulated some leguminous crops grown in Sohag governorate, were conducted in this present study. According to the 16S rDNA sequencing analysis, all of isolates were belong to genus Rhizobium which is commonly colonizing root nodules of different leguminous crops. Among of all the 5 bacterial isolates only EMR2 gave 100% of similarity with Rhizobium pusense strain NRCPB10 NR_116874.1 while, EMR1 isolate exhibited 99.58% of similarity with Rhizobium binae strain BLR195 NR_137242.1. The two isolates EMR4 and EMR5 showed (97.35 and 97.14%, respectively) similarity with the two bacterial strains Rhizobium aegyptiacum strain 1010 NR_137399.1 and Rhizobium bangladeshense strain BLR175 NR_137241.1. Finally the isolate EMR3 was similar to Rhizobium bangladeshense strain BLR175 NR_137241.1 with 96.88%. It was found that the 2 rhizobial species (Rhizobium bangladeshense and Rhizobium aegyptiacum) of Egyptian clover were shared the same clade. As well as it also shared Rhizobium binae of Lupine as a common ancestor. Finally, it was found that Rhizobium pusense of Peanut was the common ancestor with all other rhizobial isolates. These findings revealed that the conserved gene of these 4 Rhizobium isolates was derived from Rhizobium pusense. The obtained results showed that the genetic diversity of the rhizobial isolates that nodulate the leguminous crop at the chosen sites in the Sohag governorate is very low, which may be cause their low host specificity and ability to increase nodules formation in different leguminous crops, making them a promising bio-fertilizer for Egypt's sustainable crop production.