Tigernut (Cyperus esculentus Lativum) is an important but understudied and underutilized crop in Ghana. The tubers are highly appreciated for their health benefits and nutritive value. To contribute to the conservation process of tiger nut and identify elite genotypes, this study was conducted to assess phenotypic variability in tiger nut genotypes in Ghana. Sixty-four (64) genotypes were collected from major tiger nut growing areas in Ghana. The genotypes were field-grown and characterized based on phenotypic and yield traits. Similarity coefficient (Bray-Curtis) was between 0.82 and 0.98, indicating low variability in both qualitative and quantitative characters. The cophenetic correlation coefficient was 0.64. The genotypes were mainly brown with only a few black (6) tubers from the central region. Materials collected from parts of the eastern region (Aduamoah) generally recorded the highest tuber weight. Tuber weight depended on plant height and number of tillers. There were high tillering genetic materials among the genotypes. Tubers were categorised as oval (10), ovoid (33), or oblong (15). The genotypes clustered into two groups based on shoot and tuber characteristics, rather than on geographical origin. The low genetic diversity among the genotypes suggested either the possible existence of a network among tiger nut farmers in Ghana in circulating the planting material or some form of seed sorting for uniform and homogenous planting materials has been carried out over the years. Our results point to the imperativeness to expand the genetic base of the tiger nuts to facilitate its improvement in Ghana.

Dioscorea praehensilis Benth. is a semi-wild yam species and a valuable source of resistance trait genes. To access the agronomic and tuber quality performance, eleven quantitative phenotypic traits were used to discriminate and identify promising accessions among 162 accessions of D. praehensilis collected in Ghana. Significant and high genetic variability (p < 0.001) for all eleven quantitative traits was found among the evaluated accessions. Moderate broad-sense heritability (H²) (30–60%) was observed for all the evaluated quantitative traits except the response to YMV and tuber hardness. The accessions were clustered into three groups; each cluster displayed genotypes with good potentiality for the different traits evaluated. Path coefficient analysis revealed positive contributions (p < 0.01) of the number of tubers per plant, tuber length, tuber width, stem internode length, number of internodes, and tuber flesh hardness to the total tuber weight per plant. Through the multi-trait genotype–ideotype distance index (MGIDI), 24 accessions were identified from the 162 evaluated accessions as top-ranking and could be used as progenitors for trait introgression. The results of this study provide insight for future yam breeding and improvement programs in West Africa.

Yam (Dioscorea spp.) is an important food security crop in the tropics and subtropics. However, it is characterized by a narrow genetic base within cultivated and breeding lines for tuber yield, disease resistance, and postharvest traits, which hinders the yam breeding progress. Identification of new sources of desirable genes for these traits from primary and secondary gene pools is essential for this crop improvement. This study aimed at identifying potential sources of genes for yield and quality traits in a panel of 162 accessions of D. praehensilis, a semi-domesticated yam species, for improving the major yam species, D. rotundata. Significant differences were observed for assessed traits (p < 0.05), with D. praehensilis genotypes out-performing the best D. rotundata landraces for tuber yield (23.47 t ha⁻¹), yam mosaic virus (YMV) resistance (AUDPC = 147.45), plant vigour (2.43) and tuber size (2.73). The study revealed significant genotypic (GCV) and phenotypic (PCV) coefficients of variance for tuber yield, YMV severity score, and tuber flesh oxidation. We had also a medium-to-high broad-sense heritability (H²b) for most of the traits except for the dry matter content and tuber flesh oxidation. This study identified some promising D. praehensilis genotypes for traits such as high yield potential (WNDpr76, CDpr28, CDPr7, EDpr14, and WNDpr63), resistance to YMV (WNDpr76, CDpr7, EDpr14, CDpr28, and EDpr13), high dry matter content (WNDpr76, CDpr28, and WNDpr24), low tuber flesh oxidation (WNDpr76, CDpr5, WNDpr31, CDpr40, and WNDpr94) and high number of tubers per plant (WNDpr76, CDpr7, CDpr68, CDpr29, and CDpr58). These genotypes could, therefore, be employed in breeding programmes to improve the white Guinea yam by broadening its genetic base.

Background: Yam production in sub-Saharan African countries faces challenges due to susceptibility to yam mosaic virus (YMV) disease, leading to significant yield losses. Dioscorea praehensilis, a semi-cultivated yam species known for its high yield and resistance to YMV, can be utilized as a new variety and a gene source to enhance tuber yield and YMV resistance of White Guinea yam. Investigating the genetic basis of tuber yield-related traits and YMV resistance in D. praehensilis through association mapping will facilitate the traits discovery and deployment into the yam breeding program.Methodology: A total of 132 D. praehensilis genotypes were evaluated in 2022 and 2023 seasons for tuber yield per plant, tuber size ratio and for mosaic virus severity response. The genotypes were sequenced using SNP markers generated from Diversity Array Technology Platform. The trait association analysis was conducted using mixed linear model implemented in GWASpoly package followed for putative genes analysis.Results: Population structure and phylogeny analyses using 4,525 single nucleotide polymorphism (SNP) markers grouped the 132 D. praehensilis genotypes into three clusters. Using multiple gene action models which include dominant, additive, and general models, 27 SNP markers were significantly identified to be associated with the tuber yield, tuber size ratio and yam mosaic virus severity. Of these 27 SNPs, we identified three and two SNP markers for tuber yield and yam mosaic virus severity, respectively as stable markers across years. Using gene annotation, we identified 10 putative genes such as Serine/threonine-/dual specificity protein kinase, catalytic domain involved in starch biosynthesis and Ribosomal protein L5 involved in defense signaling against virus diseases. The marker effect revealed that alleles CC and TT were associated with high tuber yield, while AA and AC were linked with low tuber yield. For YMV severity response, alleles CC and CT were linked with low YMV severity, while TT was associated high YMV severity prediction.Conclusion: The results of this study offer valuable insights into comprehending the functional networks involved in developing strategies to enhance tuber yield and resistance to yam mosaic virus in Dioscorea spp. The markers and candidate genes discovered in this research will serve as crucial genomic resources for selection of D. praehensilis and other yam species.

Introduction: Bush yam (Dioscorea praehensilis Benth.) is an important semi-domesticated food crop in West Africa. Limited information on the genetic architecture and its poor post-harvest tuber quality traits significantly hinder its use as food and source of income. Hence, dissecting the genetics underlying the expression of its post-harvest tuber quality traits is essential for establishing proper breeding schemes.Methods: In this study, 138 D. praehensilis accessions collected in Ghana were sequenced using Diversity Array Technology (DArTSeq). The materials were profiled for dry matter content (DMC), tuber flesh oxidation (TBOXI) and for tuber flesh hardness (TBhard) during two cropping seasons.Results and discussion: Diversity assessment using population structure, principal component analysis and hierarchical clustering methods revealed the presence of three major groups. Six genetic models were used for the trait association analysis using multiple random locus mixed linear model (MrMLM). Sixteen SNP markers distributed across the yam genome were identified to be associated with the evaluated traits. The associated SNP markers displayed a phenotypic variance ranged from 4.22% in TBHard to 16.92% in TBOXI. A total 25 putative candidate genes were identified around the SNP markers. The putative genes were identified to play key roles in tuber bulking, oxidative browning and starch hydroxylase. This study provides a valuable insight on the genetics underlying tuber quality traits in bush yam and opens avenues for developing genomic resources to improve D. praehensilis.

The tiger nut is a valuable crop that has been overlooked and underutilized. The tubers of this plant are highly valued for their nutritional benefits and health advantages. This study aimed to evaluate the genetic potential of 42 tiger nut genotypes using a multitrait index based on factor analysis and genotype‐ideotype distance (MGIDI). The experiment involved a randomized complete block design with three replications, assessing 10 agronomic and tuber yield traits. The results showed significant variations among genotypes for all traits, which indicates the presence of genetic potential that can be harnessed for crop enhancement. The MGIDI index provided an increased total genetic gain of 78.58% for the desired traits. Specific genotypes, including PUT‐b (FA1), ADU‐b (FA2), OBR‐B, ENK‐B, ASU‐b (FA3), and BEP‐B (FA4), were identified as the top candidates for simultaneous improvement of the measured traits in tiger nut. This demonstrates the efficiency of the index in selecting superior genotypes, offering a data‐driven approach to breeding programs aimed at optimizing tiger nut yield and quality. Furthermore, the identification of specific high‐performing genotypes provides valuable genetic resources for future research and commercial cultivation. These findings contribute to the broader goal of improving food security and diversifying agricultural production. By promoting the genetic enhancement of tiger nut, this study supports its potential as a sustainable crop with significant nutritional and economic benefits.