Diversity of white Guinea yam (Dioscorea rotundataPoir.) cultivars from Benin as revealed by agro-morphological traits and SNP markers

Abstract

White Guinea yam (Dioscorea rotundata Poir.) is indigenous to West Africa, a region that harbours the crop's tremendous landrace diversity. The knowledge and understanding of local cultivars’ genetic diversity are essential for properly managing genetic resources, conservation, sustainable use and their improvement through breeding. This study aimed to dissect phenotypic and molecular diversity of white yam cultivars from Benin using agro-morphological and single nucleotide polymorphism (SNP) markers. Eighty-eight Beninese white Guinea yam cultivars collected through a countrywide ethnobotanical survey were phenotyped with 53 traits and genotyped with 9725 DArT-SNP. Multivariate analysis using phenotypic traits revealed 30 traits as most discriminative and explained up to 80.78% of cultivars’ phenotypic variation. Assessment of diversity indices such as Shannon–Wiener (H′), inverse Shannon (H.B.), Simpson's (λ) index and Pilou evenness (J) based molecular and phenotypic data depicted a moderate genetic diversity in Beninese white Guinea yam cultivars. Genetic differentiation of cultivars among country production zones was low due to the high exchange of planting materials among farmers of different regions. However, there was high genetic diversity within regions. Hierarchical clusters (HCs) on phenotypic data revealed the presence of two groups while HCs based on the SNP markers and the combined analysis identified three genetic groups. Our result provided valuable insights into the Beninese white Guinea yam diversity for its proper conservation and improvement through breeding.

Exploring the Bush yam (Dioscorea praehensilis Benth) as a Source of Agronomic and Quality Trait Genes in White Guinea yam (Dioscorea rotundata Poir) Breeding

“…These traits, including tuber yield, number of tubers per plant, tuber size, plant vigour, tuber hardness, YAD severity, dry matter content, and tuber oxidation could be utilized in evaluating genetic diversity among related Dioscorea spp. Agre et al [12,38,40] has reported the significant contribution of these traits in discriminating yam accessions.…”

“…Along with D. cayenensis and D. alata, they represent more than 95% of produced yam worldwide [1,11]. Farmers and consumers' preferences for a white Guinea yam variety depends on some key traits such as high tuber yield potential, low tuber flesh oxidation/browning, reduced tuber flesh hardening, high dry matter content, and tolerance to YMV and YAD [12]. Accordingly, the genetic improvement of this yam species will have a tremendous impact on food security and poverty alleviation if varieties combining those traits are developed and distributed to the predominantly resource-poor farmers of West Africa.…”

“…Thus, the knowledge of the genetic diversity and ease of gene flow among and within yam species is vital prior designing an inter-specific breeding programme. Based on previous reports, yam breeding has been using a narrow genetic base in developing new varieties for agronomic traits such as resistance to YMV, tuber flesh oxidation and colour, dry matter content, etc., which has resulted in slow progress and low genetic gain in past years [12]. This was partly explained by the vegetative propagation (planting tubers) used for yam cultivation since its domestication.…”

“…This species has a high yield potential, tolerance to insect pests and diseases, longer in-soil storage aptitude, and ability to flower and set fruits profusely [22]. In addition, spontaneous and controlled hybridizations of this species with the white Guinea yam have been reported in West Africa [12,23]. Thus, this species is a promising candidate in the effort of broadening the genetic base of the white Guinea yam and increase in the genetic gain for critical traits.…”

Diversity of Water Yam (Dioscorea alata L.) Accessions from Côte d’Ivoire Based on SNP Markers and Agronomic Traits

“…For the conservation of natural reserves, such as forests and savannah, and sustainable management of yam genetic resources, there is a need to provide farmers with improved varieties from diverse genetic backgrounds that combine high yields with pest and disease resistance and acceptable tuber quality [17]. Such an approach requires a thorough understanding of the genetic diversity within the existing germplasm for the effective selection of parental clones for hybridization [18].…”