Simple and robust sex determination in papaya (Carica papaya L.) cultivars using SCAR marker

For viable papaya production, more hermaphrodite plants are needed than male and female (though they produce inferior fruits). To this end, the sex of the plants must be ascertained early in their growth cycle, which is not possible with conventional methods. Molecular marker has shown its utility for this purpose, and in this study, 100 seedlings of the CO 7 gynodioecious variety and 100 seedlings of the CO 8 dioecious variety that were released from this university were analysed for their sex using the RAPD-SCAR (randomly amplified polymorphic DNA-sequence characterised amplified region) marker, T12. In those lines under investigation, the T12 marker's presence indicated male lines, while its absence indicated female or hermaphrodite lines. To confirm that there was no experimental error - that is, the lack of the SCAR marker was caused by the non-existence of the complementary target region - an oligomer primer called OPA 04 was initially employed as a control to validate the molecular marker system among the lines under investigation. Results of this study have shown that T12 has achieved 97% and 98% accuracy in correctly identifying the male and hermaphrodite flowers in the field in CO 7 and CO 8 accessions, respectively. A similarity search of the sequences of the polymerase chain reaction (PCR) product amplified by T12 from CO 7 and CO 8 has highlighted that they matched with male-specific regions of the papaya Y chromosome. Further, it was estimated that by employing molecularly certified papaya seedlings with predetermined sex, farmers could save up to 55% on labour costs when compared to approaches that use seedlings from conventional ways by implying the removal of male plants. Thus, the findings of this study help growers and breeders to identify sex early and guarantee profitable papaya production.