Genetic Diversity and Population Structure Analysis of Noug (Guizotia Abyssinica) Accessions Collected from Ethiopia Using Microsatellite Markers
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Date
2021-06
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Addis Ababa University
Abstract
Abstract
Noug (Guizotia abyssinica) is an Ethiopian indigenous oilseed crop cultivated primarily for
its oil and various economic importances. Its production and productivity is very low due to
different constraints. The crop has receiveda littleattention in implementing improvement
programs and until very recently remained as underutilized oilseed crop. Crop improvement
requires the availability and understanding of the genetic resource in terms of genetic
variation and population structure.However, estimationofgenetic diversity of Noug with a
wider representation of Ethiopia’s Noug growing regions using reliable molecular marker
such as, microsatellite markers are rare. Thus, this study was aimed to uncover the extent of
genetic diversity and population structure of 161 Noug genotypes collected from Ethiopia
using 13 microsatellite markers. The analysis revealed a total of 158 alleles generated with a
mean of 12.15 per locus. All the 13 microsatellite markers were polymorphic and highly
informative with a mean polymorphic information content (PIC) value of 0.82. The genetic
diversity indices across the 14 collection regionsindicated the presence of higher genetic
variability among genotypes; including the Shannon’s information index (I) which ranged
from 0.89 to 1.26 with a mean value of 1.57. Observed heterozygosity (Ho), expected
heterozygosity or gene diversity (He), unbiased expected heterozygosity (uHe) was0.17, 0.74,
and 0.79, respectively. Genotypes from Shewa, Wollo, Gojjam, Tigray and Benishangul Gumuz (B/G), shared the highest in both expected hetrozygosity or gene diversity and
unbiased expected heterozygosity. Individuals in the populations had a fixation index (F)
ranging from 0.67 to 0.80, with a mean of 0.77. The percentage of polymorphic loci (%Pl) in
all the populations showed the highest (100%) and lowest (94.33%) with a mean of
99.19%.The pairwise Nei’s genetic distance showed the highest between Eritrea and Bale
(0.892) followed by Eritreaand Illubabor (0.875).AMOVA revealed that 96.06% of the total
genetic variation was attributed to within populations while only 3.94% was attributed to
among populations, indicatingthat the highest variation was between genotypes rather than
variation due to geographic distances. The NJ or UPGMA cluster and PCOA poorly grouped
the genotypes based on their origin indicating high gene flow or seed exchange across
geographic regions.Furthermore, the model-based population structureanalysis weakly
inferred the predefinedpopulations into K=2 withconsiderable genetic admixture among tested
populations.In conclusion,the microsatellites used in the present study are highly informative
and could be used in future marker assisted breeding. Genotypes from Shewa, Wollo, Gojjam,
Tigray and B/G are identified as hotspot areas for their high genetic diversity. They also
showed the highest number of private alleles in which special focus should be given in these
areas to implement breeding and future improvement programs.
Key words/Phrases; Cluster analysis, Gene flow, Heterozygosity, hotspots, SSR Markers
Description
Keywords
Cluster analysis,, Gene flow,, Heterozygosity,, Hotspots,, SSR Markers