Crop Biotech Update

Genome Analysis of African Yam Backs Niger River as Cradle of African Agriculture

May 8, 2019

A team of scientists published the results of their work that proved that the African Yam's expansion of cultivation started in the Niger River basin. Moreover, the results highlighted that the African Yam actually descended from a forest species. This is contrary to an assumption that sub-Saharan African plants mostly arose in tropical savannahs.

Yam is a key crop in Africa, second only to cassava in terms of production. Dioscorea rotundata is the most cultivated yam species, and it has two close wild relatives: one savannah species (D. abyssinica) and one forest species (D. praehensilis). The scientists speculated that the domesticated yam was likely to come from one of the two wild relatives, or from hybridization between the two. After whole-genome re-sequencing of 167 wild and cultivated species of yams, along with sophisticated statistical modeling, results showed that the cultivated yam was domesticated from the forest yam species.

The findings led to the support of the hypothesis that the vicinity of the Niger River basin played a major role in the domestication of African crops and is comparable to the Fertile Crescent in the Near East. The study also showed that the origin crop domestication covers a more restricted site in the western Sahel near the Niger River basin, challenging the idea that the origin of crop domestication covers a bigger area between Senegal and Somalia.

The history of crop domestication in sub-Saharan Africa is much less documented and archaeologically fragmented. By piecing together the origins of domestication of crops, yam among them, scientists have a better view of where the crops being used today came from. Understanding a crop's origins and the genetic exchange among its relatives may lead to the future studies of hybridization to improve a crop even further.

Read the full article published by Science to know more.