Genetic diversity and population structure analysis of Ghanaian and exotic cassava accessions using simple sequence repeat (SSR) markers
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Date
2020-01-31
Journal Title
Journal ISSN
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Publisher
Heliyon
Abstract
Genetic diversity is fundamentally important in crop improvement and provides plants with the capacity to meet
the demands of changing environments. This work was carried out to assess the diversity and the extent of genetic
relatedness among a number of assembled cassava (Manihot esculenta Crantz) accessions. We conducted a microsatellite
marker analysis of 89 cassava accessions collected from Ghanaian and exotic sources. These accessions
were assayed using 35 simple sequence repeat (SSR) markers. A total of 167 alleles were detected from 35
polymorphic markers with an average of 4.77 alleles per locus. High allelic frequency was detected across the
accessions, ranging from 0.32 to 0.99 with an average of 0.62 per marker. Observed heterozygosity ranged from
0.03 - 0.97 across the accessions. Polymorphism information content (PIC) ranged from 0.03 to 0.78 with a mean
of 0.45, indicating high level of polymorphism across the accessions. Comparatively, higher number of alleles,
gene diversity and observed heterozygosity were detected among the local accessions compared with the exotic
accessions indicating rich genetic diversity among them. Population structure analysis based on STRUCTURE
identified two subpopulations and a large number of admixtures. Cluster analysis based on the neighbour joining
algorithim further separated the collection into seven sub-groupings irrespective of geographical origin. This
indicates the possible sharing of common genomic regions occurring across the accessions. High allelic frequency
differences and levels of heterozygosity were observed among the germplasm. These findings indicated significant
genetic variability in the germplasm to warrant selection.
Description
Research Article
Keywords
Agriculture, Environmental science, Molecular markers, Genetic variability, Manihot esculenta Crantz, Heterozygosity