Study of the Genetic Diversity of Tiger Nut (<i>Cyperus esculentus</i>) Ecotypes of Niger Using SSR Markers

Abstract

Tiger Nuts (<i>Cyperus esculentus </i>L.), a member of the Cyperaceae family, is a plant cultivated in Niger for its tubers. The present study focuses on the molecular characterization of 10 Tiger Nuts (<i>Cyperus esculentus</i> L.) ecotypes from Niger. These Tiger Nuts ecotypes were collected in the Tiger Nuts producing regions of Niger (Dosso and Maradi). DNA extraction and genetic diversity analysis were carried out at the molecular biology laboratories of ICRISAT, Hyderabad, India. Codominant nuclear and polymorphic microsatellite (SSR) markers were used. The genetic diversity parameters calculated are: polymorphism rate (P) at the 95% threshold, allelic diversity (A), observed (Ho) and expected (He) heterozygosity rate and the panmixy deviation in a subpopulation (Fis) under the Hardy-Weinberg hypotheses. The results showed that genetic diversity ranged from 0.03 (StvCyR_181a and StvCyR_327ska) to 0.60 (StvCyR_93ska) with a mean of 0.28 and. For the Tiger Nuts producing regions, the average deficit in heterozygotes is highly significant, with a mean Fis of 0.415 (Fis, 1000 permutation test, P<0.001). A significant amount of variability (27%) from differentiation between the ecotypes studied was observed in the analysis of molecular variance. These results clearly show a genetic differentiation between the populations of the large, small and wild Tiger Nuts, grouping them into three distinct groups. The study also showed that the genetic structure of the Tiger Nuts is not linked to a particular geographical origin and that the molecular tests give us evidence of conserved variability in the Niger Tiger Nuts ecotypes.