Impacts des pratiques culturales sur l’organisation génétique des sorghos cultivés par les Lokpa au Nord-Ouest du Bénin révélés par les marqueurs SSRs

Abstract

Objective: Sorghum bicolor (L.) Moench is an important crop that the conservation and valorization are of a great priority for food security of the local populations involved in its production. The objective of this study is to analyze the impacts of the mode of traditional management on the genetic structure of the sorghum for the definition of suitable on-farm conservation strategies. Methodology and results: To implement the study, an ethnobotanic survey was first conducted in tribal area of Lokpa, one of the important ethnic groups in term of sorghum production and conservation. In the three villages investigated, 13 local names representing 10 landraces were inventoried. These varieties are traditionally classified into two principal groups according to farmer taxonomy: Talèm'la or field sorghums and Tiam'la or home sorghums. A morpho-botanic analysis of 11 accessions of these sorghum landraces collected during the investigation showed the existence of two races: guinea and caudatum. Lastly, a molecular study using 8 nuclear microsatellites (SSRs) markers revealed a relatively important genetic variability with a polymorphism rate of 87,5%, an average number of alleles of 3,125 per locus, an average PIC value of 0,32 and an estimated genetic distance between accessions averaging 0,45. UPGMA and PCoA analyses of molecular data are concordant with the farmer classification of the varieties into two groups globally confirmed. Conclusion and results’ applications: These results clearly reveal a significant impact of the farmer practices on the genetic organization of the sorghums. They are significantly important for the strategies’ definition for conservation and sustainable use of sorghum genetic resources in Benin.