Genetic Diversity and Population Structure of Cowpea [Vigna unguiculata (L.) Walp.] Germplasm Collected from Togo Based on DArT Markers

Abstract

Crop genetic diversity is a sine qua non for continuous progress in the development of improved varieties, hence the need for germplasm collection, conservation and characterization. Over the years, cowpea has contributed immensely to the nutrition and economic life of the people in Togo. However, the bulk of varieties grown by farmers are landraces due to the absence of any serious genetic improvement activity on cowpea in the country. In this study, the genetic diversity and population structure of 255 cowpea accessions collected from five administrative regions and the agricultural research institute of Togo were assessed using 4600 informative diversity array technology (DArT) markers. Among the regions, the polymorphic information content (PIC) ranged from 0.19 to 0.27 with a mean value of 0.25. The expected heterozygosity (He) varied from 0.22 to 0.34 with a mean value of 0.31, while the observed heterozygosity (Ho) varied from 0.03 to 0.07 with an average of 0.05. The average inbreeding coefficient (FIS) varied from 0.78 to 0.89 with a mean value of 0.83, suggesting that most of the accessions are inbred. Cluster analysis and population structure identified four groups with each comprising accessions from the six different sources. Weak to moderate differentiation was observed among the populations with a genetic differentiation index varying from 0.014 to 0.117. Variation was highest (78%) among accessions within populations and lowest between populations (7%). These results revealed a moderate level of diversity among the Togo cowpea germplasm. The findings of this study constitute a foundation for genetic improvement of cowpea in Togo.

A medium density DArTag single nucleotide polymorphism panel for genetic dissections and deployment in cowpea improvement

“…Results of AMOVA further revealed higher variation within the genetic populations than between the populations. A recent study using 255 cowpea accessions collected from six regions in Togo reported significant genetic variations among and within populations, with variations among individuals that were within each of the six geographic origins explaining the highest percentage (78%) of total variability (Gbedevi et al, 2021). Similar studies have been reported by several authors.…”

“…This marker density and distribution is modest for dissection of molecular diversity, genetic relatedness, population structure, linkage disequilibrium, genomic selection and even a medium resolution QTL discovery. Marker density of less than 5,000 SNPs that are well distributed across the genome have been deployed successfully to decipher genetic diversity and other molecular and genetic applications in crops (Akohoue et al, 2020;Chander et al, 2021;Gbedevi et al, 2021).…”

“…Some past genetic studies in cowpea have used F ST to assess the extent of differentiation between sub-populations. For instance, Gbedevi et al (2021) reported low to moderate pairwise F ST values in the range of 0.014 to 0.117 and a mean 0.072 among six sub-populations of cowpea accessions grouped by geographic regions in Togo. Using 15 SSR markers, Sarr et al (2021) reported genetic differentiation (F ST ) to vary from 0.018 to 0.100 among cowpea accessions collected from different regions of Senegal.…”

Genome‐wide diversity analysis suggests divergence among Upper Guinea and the Dahomey Gap populations of the Sisrè berry (Syn: miracle fruit) plant (Synsepalum dulcificum [Schumach. & Thonn.] Daniell) in West Africa

“…(2017), but whether or not autogamy predominates over allogamy has yet to be clarified. The high inbreeding coefficient also indicates that accessions investigated are near the inbred line state (Gbedevi et al., 2021), an insight that provides impetus to quickly advance breeding population development for agronomic and functional traits of importance in the species. Based on their relatively high expected heterozygosity and mean allelic richness values, the Volta population in particular, and the Eastern and Oueme populations to some extent, stand out as promising sources of genetic material for both breeding and conservation programs.…”

Genetic Diversity and Population Structure of Cowpea (Vigna unguiculata (L.) Walp.) Landraces from Portugal and Mozambique

“…This technology, based on microarray hybridizations, can detect DNA variation, and the presence versus absence of individual fragments, without the need for sequence information. DArT analysis was already applied to the germplasm characterization of barley [ 20 ], strawberry [ 21 ], macadamia [ 22 ] and, to our knowledge, very recently to cowpea from Ethiopia [ 23 ] and Togo [ 24 ].…”