Low-cost Technique Development for Sex-type Identification of Papaya Seedling

Abstract

Papaya is a dioecious plant. There are three sex types; male, female and hermaphrodite. The
hermaphrodite plant is much more beneficial for commercial planting system. Identifying sex-types can be
done based on floral morphology in their reproductive stage, about 3-4 months after transplanting. However,
sex-type can also be distinguished in their vegetative or seedling stage using molecular markers. But the
cost of this technique is still high. In this study, we aimed to reduce materials and time cost in DNA
preparation for sex-type identification using PCR-based markers. Two experiments were performed.
Experiment 1: Reliability test of sex-specific SCAR markers; DNA from fresh leaf tissue of male, female and
hermaphrodite papaya were isolated using CTAB method. Selected SCAR markers, T1 and W11, were
tested. Experiment 2: Comparisons of materials and time cost as well as the sex-type identification results,
between two DNA preparation methods, i.e. CTAB and NaOH. Sixteen seedlings of each of three cultivars,
‘Khaknuan’, ’Khakdam’ and ‘Plak Mai Lai’ were investigated. The results confirmed that T1 and W11 could
be used for sex-type identification. Using NaOH method for DNA preparation had materials and time cost
lower than CTAB method. Both DNA preparation methods revealed identical results in sex-type identification.