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Monday, August 04, 2008

DA Reports Advances in Research on Diseases Affecting Abaca and Papaya

Department of Agriculture-Biotechnology Program Office has updated the public on its recent research projects on papaya and abaca last July 30 at the University of the Philippines in Los BaƱos.

The presentation and field monitoring were done in three parts, said DA-BPO director Alicia Ilaga.

The first part was the presentation of the research done by Dr. Evelyn Mae T. Mendoza of the UPLB-Institute of Plant Breeding, together with Dr Simeona Siar and Dr Antonio Laurena, who introduced papaya ringspot virus resistance to transgenic papaya (Carica papaya) with delayed ripening trait.

This group says the target date for commercialization of the product is on 2010, and will be introduced to the market as a hybrid of papaya. The papaya variant used for the experiment was Davao solo, which, according to the scientists, was the most common papaya variant in the market today.

Through genetic engineering, the scientists were able to delay the ripening of the papaya. Then, the scientists introduced the PRSV resistance trait to the papaya with delayed ripening effect. Efforts were mainly targeted against this virus since it is the most common papaya virus in the country, crippling the industry in Luzon since 1984.

In 2003, the virus appeared in Leyte and Panay, as well as in South Cotabato and some parts of General Santos City, Davao del Norte and Davao del Sur. PRS affects all stages of plant growth, from seedling to maturity. Green concentric ringspots appear on the fruit's surface. The plant also shows yellowing, mosaic, and deformed leaves, oily streaks on the stem and petioles, stunted growth and sterile fruits.

The delayed ripening trait of papaya will ensure farmers of larger income, as this will prevent postharvest losses due to rotting and will allow the transport of the fruit to remote markets. Dr. Siar reported that in one event, the fruit reached a full 14 days without rotting. With the development of PRSV-resistant papaya with delayed ripening trait, the papaya industry will be assured of a good yield and farmers will enjoy higher incomes, Ilaga added.

Dr Teodora Dizon, also from IPB and a professor in CSC-UPLB, led the second presentation on the development of bunchy top, mosaic and bract mosaic resistance in abaca (Musa textilis) through radiation-induced mutation. The group says the product may be out in the market after four years. Dizon's team exposed the abaca plants to doses of gamma rays to induce the plant's resistance to bunchy top, mosaic and bract mosaic viruses.

Based on the study, one plant can only show resistance to only one type of virus. Dr Dizon also said that the product is competitive to the conventional plant. It is of good fiber quality and can compete with abaca plants that did not undergo irradiation. The plants will be commercialized through micropropagation.

Dr Antonio Lalusin did the last presentation on his study on the development of molecular markers in abaca for use in breeding high fiber quality and bunchy top virus resistant cultivars.
He developed hybrids by combining abaca and banana genes. Dr. Lalusin hopes to develop markers that will show which plant will possess good fiber quality, resistance to bunchy top virus and will most likely deliver higher yields.

After the presentation, the scientists showed the laboratories and the plants they were working with. The Philippines is the world's leading producer of abaca, providing 85 percent of the world's supply. The industry brings an annual income of $80 million. However, due to infestation of bunchy top virus, which is the most dominant abaca disease, the industry output is down anywhere from 30 percent and 50 percent, the Fiber Industry Development Authority reported.

Faced with this big problem, FIDA, DA-BPO and IPB are continuously pushing to develop technologies to help the abaca industry recover from the adverse impact of these debilitating diseases. Abaca plants infested with bunchy top virus will show a yellowish-white, chlorotic area on lamina and margins of unfurled leaf, mature leaves will become dark green, stiff, narrow, erect and necrotic.

The petioles begin to rise from the same plane at the upper end of the pseudostem resulting in a rosette or bunchy appearance. Infected plants may stay alive for years but they gradually become smaller and their leaves and leafsheaths turn brown before dying. (biolife news service)

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