Morpho-agronomic and genetic variation and segregation patterns of phaseolus vulgaris landraces from selected provinces of South Africa
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Date
2021
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University of Zululand
Abstract
Phaseolus vulgaris L. (dry beans) of Central American origin is a self-pollinating crop
with a low frequency of crossing. It is planted for its edible leaves, immature pods, and
dried seeds throughout the world. In South Africa, local communities grow a variety of
P. vulgaris landraces. Landraces are significant for breeding purposes because they
contain important germplasm. However, studies on variation in morphology and
genetics among P. vulgaris landraces are limited in South Africa. Thus, this study
aimed to determine the morpho-agronomic and genetic variations among P. vulgaris
landraces. P. vulgaris landraces collected from the various rural communities of four
selected provinces in South Africa were grown in a randomized complete block design
with three replications over two seasons.
Significant variations were recorded in germination percentages, vegetative and
reproductive traits. The vegetative and reproductive traits correlated positively with
each other, and with both traits. The first five informative principal components
explained 88.749% and 91.678% of the total variation in the morpho-agronomic and
segregation patterns, respectively. The landraces were clustered in a biplot and
dendrogram based on their seed coats, shape, similar morpho-agronomic traits, and
their area of origin. The 12 parents of P. vulgaris produced offspring that are different
from their parents in seed colour, shape, and size.
The genetic diversity analysis with simple sequence repeat (SSR) markers revealed
the range of genetic diversity, observed heterozygosity, and polymorphic information
content as 0.00–0.65, 0.00–0.05, and 0.00–0.58, respectively. The population
structure divided the 40 landraces into two subpopulations namely Mesoamerican and
Andean gene pools. Although there was considerable overlap among the landraces,
numerous Mesoamerican landraces carried certain seed features or genes from the
Andean gene pool, indicating a significant amount of mixing. Although, the populations
showed an overlap among the landraces as several from the Mesoamerican group
carried some seed traits or genes from the Andean gene pool, as they showed a high
level of admixture. The grouping of landraces in a principal coordinate analysis (PCoA)
and dendrogram had a similar clustering to the population structure. The landraces
demonstrating admixture were also grouped in the same cluster (dendrogram) and
similar quadrants (PCoA). The findings of the variance in morpho-agronomic and
genetics of P. vulgaris landraces can be used to improve, conserve them, and increase
their productivity.
Description
A thesis submitted to the Faculty of Science, Agriculture and Engineering in fulfilment of the requirements for the Degree of Master of Science in the Department of Botany at the University of Zululand, South Africa, 2021
Keywords
Morpho-agronomic variation, genetic variation, phaseolus vulgaris