Genetic engineering Delays Ripening in Papaya and Mango
Through modern biotechnology or genetic engineering, researchers from the Institute of Plant Breeding (IPB) College of Agriculture at the University of the Philippines Los Banos enhanced tow of the country’s major fruit crops, papaya and mango to delay their ripening traits. Fruits with longer shelf lives can be now exported to more distant countries, making them more in-demand to the local market. They stay fresh longer without special refrigeration or other storage conditions.
The process was done by cloning the ripening-related enzymes (specifically, the ACC (1-Aminocyclopropane-1-Carboxylate synthase genes) from ripe fruits of local varieties of papaya and mango. This was conducted by the research team of Dr. Antonio C. Laureana and Dr. Evelyn Mae Tecson-Mendoza, Amy Bernardo, and Marie Sol P. Hidalgo. The process of genetic engineering involved putting the ACC synthase gene in antisense direction (opposite the usual direction) in a piece of DNA vector that contains elements, which regulated the expression of the gene. Dr. Laurena’s team prepared this vector containing the ACC synthase gene, also called a gene construct.
At this point, the team of Dr. Pablito Magdalita, Dr. Violeta N. Villegas, and Bessie Yabut-Perez delivers the gene construct to plant tissues such as those of papaya by accelerated particles in an instrument called a particle gun. Because the ACC synthase gene is in antisense direction, production of ethylene is suppressed particularly at the ripening stage, thus, the ripening of the fruit is delayed.
In the P2 containment laboratory at IPB, small plantlets of papaya produced by this process are now in culture. They are eventually hardened and grown in special insect-proof screen house at the IPB compound and their fruits are evaluated fro the delayed ripening trait. For mango, the ripening related gene of ACC synthase has been cloned while somatic embryogenic tissues of mango var. Carabao have been obtained . The delivery of the gene construct into mango tissues by particle bombardment is scheduled to take place within this year.
This biotechnology project was funded by the Department of Science and Technology (DOST) – Philippine Council for Agriculture, Forestry and Natural Resources Research and Development (PCARRD) and the Australian Centre for International Agricultural Research (ACIAR). This was donde in collaboration with the University of Queensland’s Plant Genetic Engineering Laboratory under DR. Hose Ramon Botella.
Source: BAR TODAY October- December 2000, Evelyn Mae TEcson-Mendoza, IPB, UPLB