UPLB Research, Development and Extension News; TUESDAY, 11 JANUARY 2011 16:44

As early as 2005, a group of agricultural scientists at the University of the Philippines Los Baños (UPLB) developed a transgenic papaya that could stay on the shelves for four to 14 days, a delayed-ripening variety.

It was, indeed, a breakthrough in modern biotechnology in the Philippines.

Dr. Evelyn Mae T. Mendoza of the UPLB Institute of Plant Breeding (IPB), the project leader, said they could have come out with the Australian government-assisted research, but since the transgenic papaya was developed for its long-shelf life, it was still highly susceptible to the papaya ringspot virus, or PRSV disease.

Seedlings can be infected within two months of their planting and may not be able to bear fruits. Worse, those infected at a later stage produce fruits that are deformed, with ringspots and low-sensory qualities.

Like in most fruits, postharvest losses in papaya can affect anywhere from 30 percent to 40 percent of the output.

Since scientific research is a never-ending endeavor, UPLB-IPB decided to be in the forefront of developing the first-ever transgenic delayed-ripening papaya that can resist the dreaded virus.

Mendoza, a University of Massachusetts-trained biochemist, said once their transgenic papaya variety is commercialized, it will not only minimize the farmers’ postharvest losses; it will also increase the country’s competitiveness in the world market for this important fruit.

In the Philippines, total production of papaya increased, with output rising from 75,896 metric tons (MT) in 6,121 hectares in 2000 to a staggering 164,100 MT covering 9,125 hectares in 2007.

The Food and Agriculture Office (FAO) also ranked the county as 14th in world production and seventh as an exporter.

Apart from its fresh and dried fruits, the papaya has become a good source of papaine, an enzyme used in meat tenderizing and clearing of fruits and alcoholic beverages. It is also used in producing pharmaceuticals, cosmetics and beauty products.

Incidentally, UPLB-IPB was instrumental in commercializing the first Philippine hybrid papaya, the Sinta variety, which Dr. Violeta Villegas developed in 1997.

When the UPLB-IPB team started its research in 1997, it was done in collaboration with Prof. Jose Ramon Botella of the University of Queensland.

Their strategy was to delay the fruit ripening through genetic manipulation, leading to the suppression or inhibition of the key enzyme —the ACC synthase—in ethylene production during the ripening process.

While Mendoza conducted the laboratory research in Los Baños, her colleagues Dr. Antonio Laurena and Dr. Pablito Magdalita undertook one-year postgraduate studies at the University of Queensland in Dr. Botella’s laboratory.

Laurena managed to isolate and clone the ripening ACC synthase gene from our local Solo papaya and prepared the needed gene construct. Magdalita optimized the conditions for transformation and tissue culture of papaya.

Both scientists successfully transferred the technologies to the Philippine research in Los Baños. The transformed papaya plants were grown in biosafety level 2 (BL2) screenhouses and, in 2004, they obtained a proof of concept. [(JOEL C. PAREDES Articles from Outside - Internet Articles ),(Originally published by the BusinessMirror)]

Source: UPLB scientists developing delayed-ripening papaya