Genetic diversity studies in pepper (Capsicum spp)
Loading...
Date
2013-09-03
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Genetic characterization using morphological and molecular markers is imperative in making
available useful information on the genetic diversity within a species. Such information is
vital in providing the basis for proper conservation strategies and to orientate effective
breeding methods. The overall objective of this study was to examine the genetic diversity
and relatedness among in-country pepper accessions. Fifty local pepper genotypes were
characterized using 35 quantitative and qualitative traits from seedling emergence to crop
maturity. Morphological data were subjected to principal component analysis (PCA)
followed by hierarchical cluster analysis using euclidean similarity coefficient. The first four
principal components accounted for 72.44% of the total genetic variance among the 50
pepper genotypes with the larger part of the variance explained by cotyledon leaf width, fruit
width, plant height and fruit length. The study showed a great variation in fruit traits
revealing six fruit shapes and four fruit colours. Although there was substantial variation
among the accessions based on phenotypic traits, cluster analysis revealed low genetic
diversity among the accessions. Molecular analysis using 8 SSR markers generated a total of
35 alleles with an average of 4.38 alleles per locus. Polymorphism information content (PIC)
ranged from 0.20 to 0.74 with an average of 0.42. The mean values of gene diversity and
heterozygosity were 0.44 and 0.26 respectively , signifying a substantial amount of
polymorphism among the primers. Molecular cluster analysis based on UPGMA revealed a
much wider genetic dissimilarity of 0.26 to 0.90. The accessions were clustered into two
main groups at 0.26 with cluster 2 having fifteen sub-clusters at a similarity coefficient of
0.46. The study has shown that both morphological and SSR markers are effective tools in
studying genetic diversity in Capsicum species. This observed diversity among the pepper
genotypes can therefore be used for improving pepper through selection and hybridization.
Description
A thesis submitted to the Department of Crop and Soil Sciences, Faculty of
Agriculture, KNUST, Kumasi in partial fulfillment of the requirements for
the degree of
Master of Science, 2013