iPBS-retrotransposons variations: DNA fingerprinting and the evaluation of genetic diversity and population structure in international cowpea germplasm.

Cowpea belongs to the fabaceae family, originated in Africa, and grown in subtropical and tropical areas worldwide. Cowpea seeds contain high nutritional contents and play a vital role in nutritional feed for animals and humans in many countries. The present investigation aimed to check the genetic variations among cowpea germplasm collected from 6 countries using iPBS-retrotransposons markers system. Twelve highly polymorphic iPBS-retrotransposons primers were used for PCR amplification. These primers generated 200 total bands of which 188 were highly polymorphic and 94.30% polymorphism was observed. Mean values of genetic diversity indices i.e., Shannon's information index (I = 0.452), effective number of alleles (ne = 1.501), overall gene diversity (ht = 0.236), gene diversity (h = 0.298), polymorphism information content (PIC = 0.308), and average genetic distance 0.61 confirmed a great level of genetic variations in studied germplasm. Analysis of molecular variance revealed 96% variation within the population. The STRUCTURE analysis divided germplasm into 2 populations according to geographically. The Neighbor-joining tree and Principle coordinate analysis (PCoA) divided the germplasm into 3 groups and the grouping was mostly aline with STRUCTURE-based clustering. This study revealed high genetic variability in cowpea germplasm and the high values of diversity indices revealed the utility and efficiency of iPBS-retrotransposons marker system. The PCoA, Neighbor-joining tree and STRUCTURE analysis separated the accessions geographically. Analysis of molecular variance revealed 94% genetic variation within a population and Ghana 1 and Turkey 4 had the greatest genetic distance and could be recommended for breeding activities. [ABSTRACT FROM AUTHOR]