Article Fertility and Chimera Induction in cassava, Manihot esculenta Crantz interspecific hybrids By

Four interspecific hybrids between cassava and wild Manihot species were polyploidized by the application of colchicine to cutting buds. Totally tetraploid types of 2n=72 as well as sectorial and periclinal chimeras were produced. Morphological, cytogenetial and anatomical exames were efficient in identifying different types of chimers. Somatic selection applied to lateral buds of sectorial chimeras enabled obtaining totally tetraploids. The fertility of sterile interspecific hybrids was restored by chromosome duplication and reached 93 % of viable pollen in tetraploid types compared to 13 % in the diploid forms. New Manihot species have evolved due to this induced fertility. Periclinal chimeras showed high vigorisity compared to both tetraploid and diploid types. The fertile interspecific hybrids will be crossed with apomictic clones to produce triploid apomictic ones. Key words- Polyploidy, periclinal and sectorial chimera, pollen viability, hybrid fertility Cassava is an important staple crop and a food for more than 800 million people. It