Abstract:
ABSTRACT
Bush yam (Dioscorea praehensilis Benth.) is a wild yam that provides food and
contributes to the livelihoods of people in West Africa. Several socio-cultural,
nutritional and agronomic factors impede its production and commercialization. A
participatory rural survey conducted in 2019 in 23 communities across Ghana's
three main growing regions revealed poor culinary quality (39.9%) and
agronomic traits (20.7%) as the leading causes of decreasing productivity and
abandonment. A preliminary investigation of genetic diversity among 43 bush
accessions previously collected and maintained at School of Agriculture,
University of cape Coast, Central Region, Ghana using 11 simple sequence
repeats (SSRs) revealed low genetic diversity, suggesting a need for regional
germplasm collection. Quantitative traits (15) grouped 162 accessions into best
performing accessions for tuber yield and yield-related traits, best in resistance to
yam mosaic virus resistance and best for post-harvest tuber quality traits. Using
24 qualitative traits, a high variation among the accessions. Potential sources of
genes for yield and quality attributes in 162 accessions of D. praehensilis
to improve the predominant yam species, D. rotundata was evaluated. For tuber
yield (23.47 t ha-1), yam mosaic virus (YMV) resistance (AUDPC=147.45) and
tuber size (2.37), D. praehensilis accessions outperformed the best D. rotundata
landraces. Population structure analysis based on hierarchical clustering,
admixture and principal component analyses using 4,525 single nucleotide
polymorphism (SNP) markers grouped D. praehensilis accessions into five
clusters. Genome-wide association study revealed twenty-one SNPs associated
with the agronomic and tuber quality traits. The identified SNPs accounted for
approximately 16% of the total phenotypic variation. Gene annotation of
significant SNPs identified candidate genes with functions related to growth and
development of tubers, quality traits and defence mechanisms against yam mosaic
virus. This study provides the first insight into the genetic diversity and marker-
trait association of bush yam using farmers’ indigenous knowledge,
morphological and molecular approaches and genome-wide association studies
