Phenotypic and Genetic Characterization of Selected Kenyan Vigna Radiata (l.) Wilckzek (Mung Bean) Genotypes
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Date
2021
Authors
Wangari, Mwangi Jedidah
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Mung bean (Vigna radiata (L.) Wilckzeck) is a leguminous crop grown for its
nutritious seeds and as a fodder crop. Characterization of mung bean germplasm is,
therefore, a prerequisite for the use of its genetic resources. The objective of this study
was to evaluate the phenotypic and genetic variations among seven genotypes from
eastern Kenya where they are mainly grown. Phenotypic diversity was determined
using 13 morphological traits done in triplicate and the data was analysed using
Minitab software version 19.2. The Principal Components were also computed and
Eucledian distance tool used to construct the dendogram. Two main clusters I and II
were obtained with cluster I having four genotypes while cluster II comprised three
genoypes. The first and the second principal component accounted for 35.6% and
29.1% phenotypic variation respectively while cumulatively they accounted for 64.7%
of the total variation. Simple sequence repeat markers were used to assess the genetic
diversity of the seven mung bean genotypes. A set of 10 standardized Simple
Sequence Repeats markers were used and eight of them had distinct and consistent
amplification profiles while two were monomorphic. Twenty three alleles were
detected in all the 7 genotypes on all chromosomes after analysis. The average number
of alleles per locus shown by each marker ranged from 2-5 alleles and the average was
2.875 across loci. Genetic diversity, allele number and polymorphic information
content (PIC) was determined using powermarker (version 3.25) and phylogenetic tree
constructed using DARWIN version 6.0.12. Analysis of Molecular Variance was
calculated using GenALEx version 6.5. The PIC values ranged from
0.1224(CEDG056) to 0.5918 (CEDG092) with a mean of 0.3724. Among the markers,
CEDG092 was highly informative while the rest were reasonably informative except
CEDG056 which was less informative. Gene diversity ranged from 0.1836(CEDG050)
to 0.5102(CDED088) with an average of 0.3534. The Jaccards dissimilarity matrix
indicated that genotypes VC614850 and N26 had the highest level of dissimilarity
while VC637245 and N26 had lowest dissimilarity index. The phylogenetic tree
grouped the genotypes into three clusters with cluster III having one unique genotype
(VC6137B) only. Cluster I and II were further discriminated into sub clusters.
Analysis of Molecular Variance indicated that the highest genetic variation (99%) was
between individuals. Principal Coordinate Analysis depicted that two coordinates
were able to explain 66.05% of the overall genetic variation. These findings indicate
that use of agronomic traits and polymorphic SSR markers will be of great use in
germplasm characterization and determination of genetic diversity. The highly
informative marker can therefore be used in selection of parents during mung beans
plant breeding programs.
Description
A Thesis submitted in partial fulfillment of the Requirements for the award of the degree of Master of Science (Biotechnology) in the School of Pure and Applied Sciences of Kenyatta University, May, 2021
Keywords
Phenotypic and Genetic Characterization, Kenyan Vigna Radiata (l.), Wilckzek (Mung Bean) Genotypes