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The nutrient-rich tubers of the greater yam, Dioscorea alata L., provide food and income security for millions of people around the world. Despite its global importance, however, greater yam remains an orphan crop. Here, we address this resource gap by presenting a highly contiguous chromosome-scale genome assembly of D. alata combined with a dense genetic map derived from African breeding populations. The genome sequence reveals an ancient allotetraploidization in the Dioscorea lineage, followed by extensive genome-wide reorganization. Using the genomic tools, we find quantitative trait loci for resistance to anthracnose, a damaging fungal pathogen of yam, and several tuber quality traits. Genomic analysis of breeding lines reveals both extensive inbreeding as well as regions of extensive heterozygosity that may represent interspecific introgression during domestication. These tools and insights will enable yam breeders to unlock the potential of this staple crop and take full advantage of its adaptability to varied environments.

Monitoring genetic gain is crucial to ensure breeding programs' effectiveness and identify potential challenges and areas for their improvement. Our study provides a first overview of the trends in genetic gain for tuber yield and disease resistance traits in the IITA's (International Institute of Tropical Agriculture) yam breeding program. We used historical data (2010–2022) from multiple generations of past breeding cycles evaluated at 31 sites in the white Guinea yam (Dioscorea rotundata Poir) breeding pipeline and 28 sites in the water yam (Dioscorea alata L.) breeding pipeline of IITA and its national partners in West Africa. Our result shows positive genetic trends in fresh tuber yield while recording a gain of 1.38% or 99.17 kg ha−1 per year in the white Guinea yam and 2.18% or 252.41 kg ha−1 per year in the water yam breeding pipelines. Genetic trends for virus and anthracnose resistance were in the desired direction but negligible in white Guinea yam, while significant for virus and nonsignificant for anthracnose resistance in water yam. Our findings indicate that while the breeding program has succeeded in enhancing tuber yield, post‐harvest tuber dry matter content and disease resistance (yam mosaic virus and anthracnose) did not follow a similar trend in the material being developed. This implies that the yam breeding program needs to strike a balance between various traits, ensuring that increased yield does not come at a cost to food quality or disease resistance. Our results highlight the importance of continually monitoring and assessing the performance of a breeding program and making informed decisions about which traits to focus on for future improvement. Core Ideas: Periodic monitoring of genetic gain is crucial to making informed decisions about which traits to focus on.Yam breeding program needs to strike a balance between various traits for ensuring sustained genetic gain.High‐quality historical trial data crucial for assessing genetic gain trends in breeding programs. [ABSTRACT FROM AUTHOR]

BACKGROUND: Food quality traits related to the genetics of yam influence the acceptability for its consumption. This study aimed at identifying genetic factors underlying sensory and textural quality attributes of boiled and pounded yam, the two dominant food products from white Guinea yam. RESULTS: A genome‐wide association study (GWAS) of a panel of 184 genotypes derived from five multi‐parent crosses population was conducted. The panel was phenotyped for the qualities of boiled and pounded yam using sensory quality and instrument‐based textural profile assays. The genotypes displayed significant variation for most of the attributes. Population differentiation and structure analysis using principal component analysis (PCA) and population structure‐based Bayesian information criteria revealed the presence of four well‐defined clusters. The GWAS results from a multi‐random mixed linear model with kinship and PCA used as covariate identified 13 single‐nucleotide polymorphic (SNP) markers significantly associated with the boiled and pounded yam food qualities. The associated SNP markers explained 7.51–13.04% of the total phenotypic variance with a limit of detection exceeding 4. CONCLUSION: Regions on chromosomes 7 and 15 were found to be associated with boiled and pounded yam quality attributes from sensory and instrument‐based assays. Gene annotation analysis for the regions of associated SNPs revealed co‐localization of several known putative genes involved in glucose export, hydrolysis and glycerol metabolism. Our study is one of the first reports of genetic factors underlying the boiled and pounded yam food quality to pave the way for marker‐assisted selection in white Guinea yam. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Whenever there is market imperfection in an economy, governments usually intervene in form of policies or by initiating a program to check the anomaly. These sometimes can be excessive, untimely and inappropriate, which have implications on the competitiveness of a product and its substitutes. This paper examines the competitiveness of the food crop production system in Nigeria using the Policy Analysis Matrix (PAM). Both primary and secondary data were collected from 700 respondents using a multi stage sampling technique. The results show that yam, rice and cassava production generate a positive private and social profit with the highest in cassava and lowest in yam production. Similarly, government interventions have had a negative effect of about 20%, 75% and 17% on prices of yam, rice and cassava, respectively below their world prices. This study concludes that the food production system is competitive and therefore profitable under the prevailing policy framework in Nigeria if value is added. Keywords: Competitiveness, Comparative advantage, Food Crop Production System, Policy Analysis Matrix, INTRODUCTION In all parts of the world, a major concern is the eradication of poverty and hunger, which is also one of the Millennium Development Goals (MDGs). Extreme poverty effects [...]

Resistance to Yam mosaic virus (YMV), genus Potyvirus was studied in 10 populations of selected white Guinea yam (Dioscorea rotundata). Plants of resistant genotypes: TDr 35, TDr 1621, TDr 93-1, TDr 93-32, TDr 95-107, TDr 93-23, and susceptible ones: TDr 87/00211, TDr 87/00571 and TDr 95-127 were screened for their reaction to the pathogen by symptom severity scoring scale of 1-5, and by quantifying virus multiplication by triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA). Controlled crosses were made among the genotypes within and between the groups according to reactions to the pathogen. The resultant F1 progenies were evaluated for the infection by disease symptom development and by TAS ELISA to detect a symptomless infection in an insect-proof screenhouse for the assessment of inheritance of resistance to YMV. A genetic analysis of the reactions of progenies derived from the D. rotundata genotypes to inoculation with YMV strongly suggests that resistance to the virus is a dominantly inherited trait. Segregation ratios obtained from the families indicate that at least two dominant genes are involved.

The effects of 0.2% aqueous solution of colchicine on the survival rate and morphological features of five accessions of Dioscorea alata were investigated. Sprouting buds of two month old plants were treated with 0.2% colchicine and their performances were monitored until maturity. Survival of buds was lower in all the treated plants (ranging between 6.25% and 8.75%) compared to controls (between 13.25% and 15.25%). However, colchicine treated vines had higher survival rates when exposed to drought (13.8% - 24%) compared to controls (7.2% - 16.69%). Higher number of leaves, larger leaf width and fewer numbers of stomata were observed among the treated plants. The survival of buds between the treated plants and control plants was significantly different at P ≤ 0.05. The treated and non-treated plants were also significantly different at P ≤ 0.05 for leaf width in accessions TDa02/00246, TDa98/00116 and TDa99/00240, and for stomata number in accessions TDa02/00151 and TDa02/00246. Our results suggest that colchicine can be used to induce mutagenic changes in yam which may be of agronomic importance in the production of the crop.