Genetic Diversity among Cowpea (Vigna unguiculata (L.) Walp.) Landraces Suggests Central Mozambique as an Important Hotspot of Variation

Ana Maria Figueira Gomes,José C Ramalho,Pedro Talhinhas,David Draper,Rafael Massinga,Paula Batista Santos,Ana I Ribeiro-Barros,Nascimento Nhantumbo,Isabel Marques,Fernanda Simões

doi:10.3390/agronomy10121893

Abstract

Cowpea is a multiple-purpose drought-tolerant leguminous pulse crop grown in several dry tropical areas. Its domestication center is thought to be East or West Africa, where a high level of genetic diversity is apparently still found. However, detailed genetic information is lacking in many African countries, limiting the success of breeding programs. In this work, we assessed the genetic variation and gene flow in 59 Vigna unguiculata (cowpea) accessions from 10 landraces spanning across six agro-ecological zones of Mozambique, based on nuclear microsatellite markers. The results revealed the existence of high genetic diversity between the landraces, even in comparison to other world regions. Four genetic groups were found, with no specific geographic pattern, suggesting the presence of gene flow between landraces. In comparison, the two commercial varieties had lower values of genetic diversity, although still close to the ones found in local landraces. The high genetic diversity found in Mozambique sustains the importance of local genetic resources and farm protection to enhance genetic diversity in modern varieties of cowpea worldwide.

Highlights

Agronomy 2020, 10, x; doi: FOR PEER REVIEW www.mdpi.com/journal/agronomyAgronomy 2020, 10, x FOR PEER REVIEWCowpea
Fifty nine cowpea landraces corresponding to 10 populations were sampled in six agroecological zones (AEZ) in the provinces of Manica, Sofala and Zambezia, where cowpea is grown as an integral component of local cereal-legume cropping systems (Fig. 1): R3 (North and Central Gaza and Western Inhambane), R4 (Medium altitude areas of Central Mozambique), R5 (Low altitude areas of Sofala and Zambezia), R6 (Dry areas of Zambezia and Southern Tete), R7 (Mid-altitude areas of Zambezia, Nampula, Tete, Niassa and Cabo Delgado) and R10 (High altitude areas of Zambezia, Niassa, Angonia- Maravia and Manica)
Landraces harbor a genepool of unexplored alleles that constitute an unique set of genetic resources for breeding to improve productivity, nutritional value, adaptation and resilience to climate change [29,30,31,32]

Summary

Introduction

Agronomy 2020, 10, x; doi: FOR PEER REVIEW www.mdpi.com/journal/agronomyAgronomy 2020, 10, x FOR PEER REVIEWCowpea Walp), known as black eye pea, is a major annual grain legume mostly grown in dry tropical areas of Latin America, South Asia and Africa [1] It is cultivated mainly for its grains, which have a high content of proteins (20-32%) and carbohydrates (50-60%). Cowpea has an essential role in the human diet in many developing countries being referred as the “poor man’s meat” [3]. As a legume, it is an important component of traditional cropping systems since it fixes atmospheric nitrogen and contributes to soil fertility improvement in smallholder farming systems where little or no fertilizer is used [4]. Cowpea is known to be drought tolerant when compared to other crops, the productivity of cowpea varieties is hampered by erratic rainfall and many are sensible to heat [1]

Objectives

Methods

Results

Conclusion