Variability and genetic merits of white Guinea yam landraces in Nigeria

Abstract

IntroductionLandraces represent a significant gene pool of African cultivated white Guinea yam diversity. They could, therefore, serve as a potential donor of important traits such as resilience to stresses as well as food quality attributes that may be useful in modern yam breeding. This study assessed the pattern of genetic variability, quantitative trait loci (QTLs), alleles, and genetic merits of landraces, which could be exploited in breeding for more sustainable yam production in Africa.MethodsA total of 86 white Guinea yam landraces representing the popular landraces in Nigeria alongside 16 elite clones were used for this study. The yam landraces were genotyped using 4,819 DArTseq SNP markers and profiled using key productivity and food quality traits.Results and discussionGenetic population structure through admixture and hierarchical clustering methods revealed the presence of three major genetic groups. Genome-wide association scan identified thirteen SNP markers associated with five key traits, suggesting that landraces constitute a source of valuable genes for productivity and food quality traits. Further dissection of their genetic merits in yam breeding using the Genomic Prediction of Cross Performance (GPCP) allowed identifying several landraces with high crossing merit for multiple traits. Thirteen landraces were identified as potential genitors to develop segregating progenies to improve multiple traits simultaneously for desired gains in yam breeding. Results of this study provide valuable insights into the patterns and the merits of local genetic diversity which can be utilized for identifying desirable genes and alleles of interest in yam breeding for Africa.

Multi-Trait Selection Index for Simultaneous Selection of Water Yam (Dioscorea alata L.) Genotypes

“…The results delineated the possibility of indirect selection of traits that showed a positive correlation, such as yield and its related traits (plant vigor and number of tubers per plant) with tuber quality traits. A positive correlation between yield and yield related traits has also been reported by other researchers in yam (Agre et al [23], Adewumi et al [24], Adejumobi et al [46], Asfaw et al [49], Agre et al [35], and Padhan et al [52]). Similarly, a positive correlation was observed between dry matter content and the number of tubers per plant in all the families except for F4.…”

“…Olivoto and Nardino [18] compared several multi-trait selection indices and proposed the novel multi-trait genotype-ideotype distance index (MGIDI) to select genotypes with desirable mean performances across multiple traits while overcoming the limitations of traditional linear indices. The use of multiple traits in the selection of superior yam genotypes has been reported for D. rotundata wherein FAI-BLUP (multi-trait index-based factor analysis and ideotype design) [22] and MGIDI method [23] were used, while the MGIDI method was used for D. praehensilis [24] species, but none for D. alata species. In this context, an attempt was made in this study to assess a panel of D. alata mapping population progenies as well as their parents for selection of desirable genotypes/ideotypes based on their agronomic and quality characteristics.…”

Genetic architecture of post-harvest tuber quality traits in bush yam (Dioscorea praehensilis Benth.) germplasm through association mapping

“…The significant markers co-located with candidate genes for the evaluated traits could be essential for developing functional markers that would be useful for marker-assisted selection to enhance the development of D. praehensilis for post-harvest tuber quality traits. Detection of significant marker-trait association using GWAS has been reported in some yam species such as D. rotundata (Agre et al, 2021(Agre et al, , 2023 and D. alata (Gatarira et al, 2020;Mondo et al, 2021;Dossa et al, 2023) and other root and tuber crops such as cassava (Uchendu et al, 2021). This study detected putative candidate genes within the genomic regions of the target traits.…”

“…Many agronomic and tuber quality attributes have been studied using genome-wide association mapping in Dioscorea spp. These traits include tuber dry matter, tuber flesh color and oxidative browning in water yam (Gatarira Dossa et al, 2023), sex determination and crosscompatibility in water yam (Mondo et al, 2021), and tuber yield, tuber quality traits, yam mosaic virus resistance and sex determination and cross compatibility in white yam (Agre et al, 2021(Agre et al, , 2023Asfaw et al, 2022). This study identified seven significant markers for DMC on chromosomes 2, 3, 4, 5, 7, 17 and 19 and six significant marker for tuber flesh oxidation on chromosomes 3, 16, 17 and 19 (Table 2), which differed from SNPs identified by Gatarira et al (2020) on the two traits.…”

Farmers’ perspective toward a demand led yam breeding in Nigeria

“…Among the cultivated species, the white yam (Dioscorea rotundata) is popularly grown in West Africa, while the water yam (Dioscorea alata) has a global production outlook (Darkwa et al, 2020). Yam serves as a major source of food and income for many people along the yam value chain (Scott et al, 2000;Maikasuma and Ala, 2013;Agre et al, 2023). Yam has cultural, social, economic, and religious value in most African societies (Obidiegwu and Akpabio, 2017), as well as in most therapeutic potentials (Obidiegwu et al, 2020).…”