Abstract

S5-10

Prospecting for Root Quality Genes in Wild Relatives of Cassava (Manihot esculenta Crantz): Advanced Back Cross Quantitative Trait Loci (ABC-QTL) Mapping and Improvement of High Protein and Dry Matter Content in Cassava

Fregene M. and N. Morante

For several years now, it has been shown that the tremendous genetic potential locked up in germplasm banks can be released by shifting the paradigm from searching for phenotypes to searching for superior genes with the aid of new tools of genomics.  Cassava, a major staple food crop in many tropical countries, can serve as a cheap means of deploying adequate protein requirement amongst the poor provided the high protein content found in some wild relatives can be tapped.  Accessions of six Manihot species collected in 1995 and 1997 held as sexual seeds in cold rooms at CIAT were planted in seedling nurseries and evaluated at 8 months after planting.  Three roots were milked from individual plants and evaluated for size of storage roots, protein content and dry matter content.  Protein content of up to 14% and dry matter content of more than 50% were found in several accessions of Manihot esculenta sub spp fabellifolia, Manihot esculenta sub spp peruviana, and Manihot tristis combined with good storage root formation.  A modified advanced back cross QTL mapping approach has been initiated to introgress high protein and dry matter content from these wild species into cassava