Micropropagation of Papaya (Carica Papaya L.)

Micropropagation of papaya began three decade ago. Papaya is a polygamous fruit crop and both dioceous as well as gynodioceous varieties of papaya are being cultivated. Cloning of female papaya plants through in vitro shoot bud culture is an ideal approach. In vitro regeneration with shoot tip, excised from mature papaya plant, has been attempted (Ali & Hogan, 1976; Litz & Conover, 1978; Rajeevan & Pandey, 1986; Drew, 1988, 1992). However, most of the protocols are genotype dependent and could not be reproduced. Callus culture has also been reported in papaya (Arora & Singh, 1978; Litz et al., 1983). Papaya is recalcitrant to tissue culture. Slow rate of proliferation, poor establishment of axenic cultures and high mortality of plants during acclimatization are some of the main problems of papaya micropropagation. Most of the reports on papaya micropropagation using mature explants are therefore conflicting. Somatic embryogenesis system using hypocotyl (Fitch, 1993) or immature zygotic embryos (Fitch & Manshardt, 1990) has been successful in vitro regeneration. The micropropagation protocol described herein is based on direct somatic embryogenesis using immature zygotic embryo for somatic embryo induction and subsequent plant regeneration.