Structure of sweet potato (Ipomoea batatas) diversity in West Africa covaries with a climatic gradient

PLoS One. 2017 May 26;12(5):e0177697. doi: 10.1371/journal.pone.0177697. eCollection 2017.

Abstract

Sub-Saharan agriculture has been identified as vulnerable to ongoing climate change. Adaptation of agriculture has been suggested as a way to maintain productivity. Better knowledge of intra-specific diversity of varieties is prerequisites for the successful management of such adaptation. Among crops, root and tubers play important roles in food security and economic growth for the most vulnerable populations in Africa. Here, we focus on the sweet potato. The Sweet potato (Ipomoea batatas) was domesticated in Central and South America and was later introduced into Africa and is now cultivated throughout tropical Africa. We evaluated its diversity in West Africa by sampling a region extending from the coastal area of Togo to the northern Sahelian region of Senegal that represents a range of climatic conditions. Using 12 microsatellite markers, we evaluated 132 varieties along this gradient. Phenotypic data from field trials conducted in three seasons was also obtained. Genetic diversity in West Africa was found to be 18% lower than in America. Genetic diversity in West Africa is structured into five groups, with some groups found in very specific climatic areas, e.g. under a tropical humid climate, or under a Sahelian climate. We also observed genetic groups that occur in a wider range of climates. The genetic groups were also associated with morphological differentiation, mainly the shape of the leaves and the color of the stem or root. This particular structure of diversity along a climatic gradient with association to phenotypic variability can be used for conservation strategies. If such structure is proved to be associated with specific climatic adaptation, it will also allow developing strategies to adapt agriculture to ongoing climate variation in West Africa.

MeSH terms

  • Africa, Western
  • Climate*
  • Genes, Plant
  • Genetic Variation*
  • Ipomoea batatas / genetics*

Grants and funding

This study was partly funded by the Agropolis Foundation’s “Agropolis Resource Center for Crop Adaptation and Diversity” (ARCAD) project, the French embassy in Togo (SCAC), Institut Sénégalais de la Recherche Agricole (ISRA), Dakar, Sénégal; the Institut de la Recherche pour le Développement (IRD) in Dakar, Sénégal and Montpellier, France; the West African Economic and Monetary Union (UEMOA) grant N°11514/2011/DDS/DESFP/PAES-436 to Kodjo Glato and the University of Lomé, Togo. We thank C. Roullier and Professor K. Akpagana for early on advice on this study, V. Lebot for helpful comments and the farmers who willingly participated in the study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.