Sex differentiation in papaya (Carica papaya L.): A review

The papaya (Carica papaya L.) is among the most important fruit crops of India grown that is commercially cultivated in the tropical and subtropical regions of the globe. Papaya is a fast growing and a semi-woody tropical fruit tree with a short juvenile phase of 3 to 8 months. Papaya is by far the best known and economically most important species of the family caricaceae which is basically grown for its edible, vitamin-rich fruits and to a lesser extent also for their milky latex. In papaya, sex form is one of the most important trait affecting its production and genetic improvement. Being a polygamous plant, it has three types of sex forms, viz. male, female and hermaphrodite. Among these forms only the female ones are stable in flowering, fruiting and fruit production under both tropical and sub-tropical climatic conditions. However, they cannot be distinguished either at the seedling stage or other vegetative growth stages before flowering. In cross pollinated fruit crops such as papaya, the identification of the appropriate sex type of the progeny for commercial planting is of utmost importance, since only the female and hermaphrodite plants are grown for fruits. So to overcome this problem several efforts were made to identify morphological and physiological parameters related to sex identification and gene-linked molecular markers associated with sex differentiation. The identification of desired sex form in papaya at early stage would result in higher fruit production and increased profitability.