Gene Pools and the Genetic Architecture of Domesticated Cowpea

Abstract

Cowpea [Vigna unguiculata (L.) Walp.] is a major tropical legume crop grown in warm to hot areas throughout the world and especially important to the people of sub-Saharan Africa where the crop was domesticated. To date, relatively little is understood about its domestication origins and patterns of genetic variation. In this study, a worldwide collection of cowpea landraces and African ancestral wild cowpea was genotyped with more than 1200 single nucleotide polymorphism markers. Bayesian inference revealed the presence of two major gene pools in cultivated cowpea in Africa. Landraces from gene pool 1 are mostly distributed in western Africa while the majority of gene pool 2 are located in eastern Africa. Each gene pool is most closely related to wild cowpea in the same geographic region, indicating divergent domestication processes leading to the formation of two gene pools. The total genetic variation within landraces from countries outside Africa was slightly greater than within African landraces. Accessions from Asia and Europe were more related to those from western Africa while accessions from the Americas appeared more closely related to those from eastern Africa. This delineation of cowpea germplasm into groups of genetic relatedness will be valuable for guiding introgression efforts in breeding programs and for improving the efficiency of germplasm management.

Genetic diversity and population structure of Bambara groundnut (Vigna subterranea (L.) Verdc.): synopsis of the past two decades of analysis and implications for crop improvement programmes

“…Specifically, for Bambara groundnut domestication, a comparative analysis with other native African Legume, most appropriately cowpea, will present a contextual framework. Recently, new genetic data on cowpea (Huynh et al 2013) contradicted previously held hypothesis on domestication of the crop. Huynh et al (2013) in their analysis point to two distinct gene pools of Western and Eastern African sub-populations (each more closely related to the wild relatives natives in the respective regions).…”

“…Genetic diversity, population structure analysis and its implication for crop improvement programmes Molecular genetic diversity analyses have been used to aid breeding decisions and germplasm conservation agenda in crop species (Choudhary et al 2013;Huynh et al 2013). Specifically for Bambara groundnut, various molecular analyses of diversity have been reported to either argument or validate the various reports based on phenotypic descriptors (Table 6; Pasquet et al 1999;Massawe et al 2003aMassawe et al , 2002Olukolu et al 2012;Aliyu and Massawe 2013;Mayes et al 2013;Molosiwa et al 2015).…”

“…Huynh et al (2013) in their analysis point to two distinct gene pools of Western and Eastern African sub-populations (each more closely related to the wild relatives natives in the respective regions). Contrary to the general belief that cowpea and sorghum occupy the same agro-ecology and often intercropped historically; therefore it may have followed single domestication event of Westward to Europe (via Middle East), Huynh et al (2013) concluded that two divergent domestication events namely Western and Eastern Africa may have occurred.…”

“…(He et al 2012) and cowpea (Vigna unguiculata (L.) Walp.) (Huynh et al 2013), is an important on-going component of their crop improvement. The significance of 'underutilized' crop species (also known as 'minor', 'orphan' or 'neglected') for global food security is gradually gaining the attention of the international research community and food security policy organizations (Jaenicke and Höschle-Zeledon 2006;Massawe et al 2016).…”

Molecular Markers for Genetic Diversity Studies in African Leafy Vegetables

“…Automation with SNPs is also possible and is used for example for identification of genotypes and construction of high-density genetic maps [53]. Only recently the first application of SNPs in genetic diversity studies in African leafy vegetables appeared aiming at genotyping of a worldwide collection of landraces and African ancestral wild cowpeas using 1200 SNPs [54], which in contrast to earlier statements revealed the presence of two major gene pools (eastern and western Africa) and divergent domestication events in cultivated cowpeas in Africa. Further reduction in costs for next generation sequencing will allow low cost SNP detection and GBS (genotyping by sequencing) or related techniques to be used even in crops with minor economic importance in the near future.…”