Genetic diversity and symbiotic efficiency of rhizobial strains isolated from nodules of peanut (Arachis hypogaea L.) in Senegal

ARLETTE ZAIYA ZAZOU; DANIEL FONCEKA; SALIOU FALL; FABRA, A.; IBÁÑEZ, F.; SARAH PIGNOLY; ADAMA DIOUF; OUMAR TOURÉ; MATHIEU FAYE; VALERIEU HOCHER; DIÉGANE DIOUF; SERGIO SVISTOONOFF

AGRICULTURE, ECOSYSTEMS AND ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018

0167-8809

Abstract: Cultivated peanut (Arachis hypogaea L.) was introduced inSenegal centuries ago from South America, its region of origin. Todaypeanut is widely cultivated in Senegal and has become the largest cashcrop produced in the country. This is in part due to the development ofvarieties adapted to the local environment, particularly regardingdrought resistance. Many other traits were included in breeding programsbut little attention has been paid to the symbiotic capabilities ofpeanut which is able to form nitrogen-fixing nodules in association withsymbiotic rhizobia. Scarce information is available on rhizobia thatnodulate peanut in Senegal, their diversity, their origin or theirsymbiotic efficiency. Here we report the genetic and phenotypiccharacterization of 35 native strains isolated from peanut nodulestrapped from soils coming from three different agroecological zones inSenegal. Using phylogenies based on the IGS and nodC genes we show thatnative strains are grouped in three main clusters maned A, B and Ccontaining Bradyrhizobium strains. Native strains from cluster Agenerally produced a low number of effective nodules and although thiscluster contains numerous strains isolated from peanut, native strainsare often closer to strains isolated from local Legumes. Native strainsof cluster B usually produced an intermediate number of nodules and moststrains were efficient. Remarkably this cluster does not contain anystrain previously isolated from peanut. Native strains of cluster C arealso close to strains isolated from local Legumes. We found that allstrains from cluster C were rather ineffective but they induced theformation of large numbers of nodules.Taken together our results show that in Senegal peanut is able to recruitboth effective and ineffective Bradyrhizobium and points to ways toenhance peanut performance by increasing the competitiveness of effectivestrains.