Cytogenetic behaviour of the interspecific hybrid of Manihot neusana Nassar and cassava, M. esculenta Crantz, and its backcross progeny

An interspecific hybrid between cassava, Manihot esculenta Crantz, and M. neusana Nassar and the backcrossed progenies was examined meiotically and mitotically. The F1 hybrid showed irregular meiosis due to unpaired chromosomes. The backcrossed progeny ranged in fertility from 17.7 to 35.8%. Meiotic restitution was also observed in all of the hybrids. Diploid pollen formation also occurred and ranged from 0.6 to 1.6%. Irregular meiosis among the F1 hybrid produced aneuploidy in backcrossed progeny. When the F1 hybrid was used as the maternal plant in backcrosses with cassava, this improved seed setting in the BC1 progenies, whereas the reciprocal backcross produced sterile progenies. Key words: Wild species, meiotic restitution, aneuploidy, diploid gamete