Enzymes and intermediates in ethylene production in two cultivars of durian fruits
2000
Peerasak Chaiprasart(Kasetsart University. Kamphaeng Saen Campus, Nakhon Pathom (Thailand). Faculty of Agriculture. Department of Horticulture) | Jingtair Siriphanich(Kasetsart University. Kamphaeng Saen Campus, Nakhon Pathom (Thailand). Faculty of Agriculture. Department of Horticulture)
Biosynthesis of ethylene which control the ripening process of durians were studied. Durian fruit cv. Monthong and Chanee were found to have high level of 1-aminocyclopropane-1-carboxylic acid (ACC), ACC synthase and ACC oxidase activities at only one month old. When the fruit matured the activities of both enzymes, and Malonyl ACC (MACC) contents in both the husk and pulp declined to low levels. However, ACC content in the pulp increased as durian reached maturity. In another experiment, mature durians were harvested and stored at room temperature. ACC synthase activity in both the husk and pulp of both cultivars increased as the fruit ripened, but declined later. ACC synthase activity in the husk was higher than that in the pulp. The increase in ACC synthase activity in Monthong was slower than that in Chanee. ACC content in both the husk and pulp of both cultivars incrased to the highest level on the last day of storage. Chanee had higher level of ACC than in Monthong. The pulp also has higher ACC content than the husk. MACC content in Chanee increased with storage time but little amount was found in Monthong. ACC oxidase in both cultivars increased as the fruit ripened but decreased toward the end of their storage life. Chanee durian had lower ACC oxidase activity than that of Monthong. More activity of this enzyme was found in the husk as compare to the pulp. Thus, the higher ethylene production in Chanee was due to the higher level of ACC synthase activity. On the other hand, the higher ethylene production in the husk as compare to the pulp was due to the higher level of both enzymes.
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