![](/imgs/covers/nd_cover.jpg)
|
African Journal of Food, Agriculture, Nutrition and Development
Rural Outreach Program
ISSN: 1684-5358 EISSN: 1684-5358
Vol. 13, No. 1, 2013, pp. 7307-7324
|
Bioline Code: nd13015
Full paper language: English
Document type: Research Article
Document available free of charge
|
|
African Journal of Food, Agriculture, Nutrition and Development, Vol. 13, No. 1, 2013, pp. 7307-7324
en |
EVALUATING DIVERSITY AMONG KENYAN PAPAYA GERMPLASM USING SIMPLE SEQUENCE REPEAT MARKERS
Asudi, G.O.; Ombwara, F.K.; Rimberia, F.K.; Nyende, A.B.; Ateka, E.M. & Wamocho, L.S.
Abstract
Papaya is an important fruit crop, produced in Kenya for local consumption and
export. Despite a history of varietal introductions, no attempts concerned on
developing varieties suited to Kenyan conditions have been documented. The
objective of this study was to provide information on the diversity of germplasm
available in Kenya, as a precursor to systematic plant breeding program. Forty two
papaya accessions were collected from farmers’ fields located in Coast, Rift Valley,
Western, Nyanza, Central and Eastern provinces. Genetic diversity was determined
using seven simple sequence repeat (SSR) markers, computing allelic richness and
frequency, expected heterozygosity and cluster analysis. Results indicated that the
markers were highly polymorphic among the accessions, with polymorphic
information content (PIC) varying from 0.75 to 0.852 with an average of 0.81. The
genetic similarity among the 42 papaya accessions ranged from 0.764 to 0.932 with
an average of 0.844 showing that most papaya accessions used in this study were
closely related. About 96.9% of the pair-wise comparisons among papaya accessions
exhibited genetic similarity greater than 0.802, while less than 4% (3.1%) showed
genetic similarity lower than 0.802. The phylogenetic analysis grouped the 42
accessions into two main clusters A and B. Cluster A had four sub-clusters while
cluster B had one cluster. Accessions from Coast, and some from Rift Valley
Provinces, presented the highest variation, being scattered throughout the tree, with
little or no differentiation from most accessions, whereas some accessions from Coast
regrouped in clusters A (iv) and B. The genetic differences among the accessions
revealed by the formation of distinct clusters suggest significant genetic variability
emanation from varying sources of the papaya germplasm in Kenya. Although the
level of genetic diversity revealed by SSR markers in this study is sufficient to
distinguish between breeding lines for varietal protection, the rather narrow genetic
diversity demonstrated indicates the need to introduce new germplasm or use other
techniques such as mutation and genetic engineering to provide breeding materials for
the future improvement of papaya in Kenya.
Keywords
Kenya, papaya, genetic diversity
|
|
© Copyright 2013 - African Journal of Food, Agriculture, Nutrition and Development Alternative site location: http://www.ajfand.net/
|
|