New developed all-hermaphrodite molecular markers boost the papaya breeding efficiency

In order to solve the mystery of papaya gender control, Taiwan Seed Improvement and Propagation Station (TSIPS) cooperated with Okinawa Prefectural Agricultural Research Center (Japan) and had identified the unique tiny DNA differences in all-hermaphrodite variety ‘TSS No.7’. Based on this finding, specific molecular markers were designed and used to set up an analysis method. We expect this method could achieve 100% all-hermaphroditic character selection, and therefore improve the land use efficiency by two times, which will bring significant benefits to the papaya breeding program.

Papaya has three sex forms including female, male, and hermaphrodite. Among these, hermaphroditic fruits tend to be more elongated and smaller fruit cavity than others, and are preferred in most consuming market and cultivation regions. However, due to the genetic properties of the sex control in papaya, a maximum of 2/3 the seeds is hermaphrodite, and the remaining 1/3 are undesired female seeds. An all-hermaphrodite variety ‘TSS No.7’ was bred and registered in 2005 by TSIPS and related varieties had also been transferred to the domestic representatively seedling companies.

Papaya is one of the important tropic fruits in the world. Papaya fruit is rich in dietary fiber and vitamin A and C. Papaya is the source of a protein enzyme knows as papain, which is used on food processing and pharmaceutical industries. Furthermore, papaya seed is also an important export item and our products are popular by the global market. Its estimated export value is at least 500 million NTD per year and we look forward to continue to expand our market by using new biotechnology.

▲Fig. 1 Papaya flowers with one petal removed to show internal parts in male, female and hermaphrodite sex forms.

▲Fig. 2 The all-hermaphrodite papaya ‘TSS No.7’ has a fruit weight about 500 grams and is pear-shaped.