Current Insights on Genomic Diversity and Genetic Architecture of Primary Breeding-Goal Traits in Africa Cassava Germplasm

Cassava was introduced to Africa from Brazil in the 16th Century and since then it has emerged as one of the most important food security crop the continent due to adaptation to sub-optimal production conditions and its wide harvest window. The International Institute of Tropical Agriculture (IITA) in Nigeria and The International Center for Tropical Agriculture (CIAT) in Colombia maintain a large collection of diverse cassava germplasm, including wild species, landraces and improved breeding clones from Africa and Latin America, respectively. We carried out sequencing-based genotyping more than 2300 accessions maintained by the two centers to gain insights into the genetic diversity, population structure and first-degree relationships of two most important germplasm collections. In addition, genome-wide association analysis (GWAS) was carried out on a large set of multi-parental population to dissect the genetic architecture of several important traits, including dry-matter and carotenoid content, resistance to cassava green-mite and several other traits. The results from this ongoing work will be useful in the management and targeted use of the germplasm in breeding pipelines.