Diversity analysis of rhizobia nodulating three Nigerien morphotypes of Bambara groundnut (Vigna Subterranea (L.) Verdc.) By the PCR-RFLP technique

Bambara groundnut [Vigna Subterranea (L.) Verdc.], plays an important role in increasing the bioavailability of phosphorus even in ferrolsoils through its ability to fix atmospheric nitrogen and gives an average yields ranging from 350 to 800 kg / ha in areas where soil is poor and rainfall is low. This ability to bind atmospheric nitrogen by legumes such as Bambara groundnut [Vigna subterranea (L.)) is due to the presence of root nodules harboring colonies of Rhizobium, symbiotic bacteria. Indeed, it has been showed some diversity in the isolated nodules from the same legume and proved that, apart from the genetic difference, some strains are more efficient, more competitive than others. The objective of this study is to evaluate the diversity of the nodulating rhizobia of Bambara groundnut morphotypes of Niger. For that, the PCR / RFLP technique was used to identify the polymorphism between rhizobium strains isolated from the root nodules of three (3) morphotypes (Ne-01, Ne-09 and Ne-10) cultivated at two sites (Tara and Kollo) of two different agro-ecological areas. The analysis revealed a high diversity within populations of rhizobia nodulating of Vigna Subterranea L. A total of twenty five (25) types of IGS profiles were identified from the 68 samples analyzed with 4 dominant types (II, XI, XIV and XVI). In general, the same types of IGS for the same morphotype at both sites were observed. It also appeared that the growing area has an impact on rhizobia diversity. Thus, it has been shown that the genetic diversity of rhizobia populations is much higher in Tara (20/25 types identified) compared to Kollo (12/25 types). The distribution of rhizobia populations capable of nodulating the Vigna Subterranea L. was depended not only at the morphotype but also at the growing area.