About Dioscorea species
The genus Dioscorea includes 644 species according to which very few are used in human food (D. alata, D. cayenensis, D. rotundata, D. dumetorum, etc.). Dioscorea alata (large yam) is the most cultivated species in the world, particularly for its starchy tubers, in the highlands of Asia (tropical America, Africa and the Pacific. D. rotundata also called "white yam from Guinea", is a true cultigen and the wild species D. abyssinica and D. praehensilis have been proposed as its two candidate progenitors. The possible origin of D. dumetorum lies around the area called the "yam belt made up of Nigeria, Togo, Cameroon, Ghana, Benin and the Ivory Coast. Dioscorea zingiberensis is exclusively cultivated in China and locally called "yellow ginger".
fig1. : Dioscorea alata
fig2. : Yam Tubers
Production is mainly concentrated in the savannahs surrounding the Gulf of Guinea, i.e. 93% of world production. Africa represents 97% of world production far ahead of America (2%) and Oceania (1%). Yam is the fourth most important tuber crop globally behind sweet potato (Ipomoae spp.), potato (Solanum spp.) and cassava (Manihot esculenta). It is also the second most important in Africa behind cassava. Yam is the staple food of more than 300 million people in tropical and subtropical regions. Yams are classified as a source of energy for consumers, especially in sub-Saharan Africa, due to their high starch content, which accounts for up to 80% of their dry weight. In addition, yam contains fiber, which plays an important role in the digestive system of humans and animals.
Microsatellites as Markers
Microsatellites or SSRs or Simple Sequence Repeats are motifs generally of 1 to 6 nucleotides repeated in tandem and present in abundance in the genome of various taxa. SSR markers are known to be the most efficient and best suited for studies of diversity and genetic structuring due to their high level of polymorphism.
fig.3: Structure of two alleles of microsatellites having same flanking regions
Moussa Diouf, Yedomon Ange Bovys Zoclanclounon, Pape Adama Mboup, Erick Malédon, Ronan Rivallan, Hâna Chair, Diaga Diouf, Komivi Dossa
Genome-wide development of intra- and inter-specific transferable SSR markers and construction of a dynamic web resource for yam molecular breeding: Y2MD
https://www.biorxiv.org/content/early/2023/03/10/2023.03.09.531889.1