Whole Genome Sequencing of White Guinea Yam (Dioscorea rotundata): Towards Generating Genetic and Genomic Tools for Improvement of an African ‘Orphan’ Crop

The availability of reference genomes is facilitating the application of genomics-assisted breeding to accelerate the genetic improvement of crops.  However, the majority of crops with significant economic importance are yet to benefit from these modern tools.  White Guinea yam (D. rotundata) is a major source of food and income for millions of people in sub-Saharan Africa.  It also plays vital roles in the socio-cultural life of several societies particularly in West and Central Africa.  To enhance the improvement D. rotundata by fully exploiting modern genetics and genomics tools, generating a reliable reference sequence is a prerequisite.  To this end, an international collaborative research project was initiated by the Japan International Research Center for Agricultural Sciences (JIRCAS), Iwate Biotechnology Research Center (IBRC), and International Institute of Tropical Agriculture (IITA) to sequence the genome of D. rotundata.  Accordingly, the genome of D. rotundata has been sequenced and assembled, and about 75% of the assembly was anchored and oriented using restriction-site associated DNA (RAD)-based genetic map consisting of 21 linkage groups.  Significance of availability of the reference genome for developing genetic and genomic resources for accelerating yam-breeding programs will be discussed.  We strongly believe that this represents an invaluable resource to broaden our knowledge of the genetics of D. rotundata and provide a platform for implementing genomic-assisted breeding in this important but under-researched crop.