Down regulation of ethylene production in apples
G. Hrazdina , E. Kiss , Z. Galli , C. Rosenfield , J.L. Norelli, and H.S. Aldwinckle
Fulbright Challenges and Responses 10 th Anniversary Conference MTA Bp. April 24-25. Abstracts Book. p. 18 (2002)
2002
บทคัดย่อ
Apples are an important agricultural commdity in the world. Most apples are produced for the fresh market and have to be stored under controlled atmosphere conditions to avoid softening. The softening of fruits is the result of structural changes in the cell walls. These structural changes are caused by the hydrolytic activity of such enzymes as polygalacturronase, cellulase and the diverse hemicellulases that are under the control of the ripening hormone ethylene. Ethylene is synthesized in plants from S-adenosyl-L-methionine by a short pathway that consists of two enzymes: 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and 1-carboxylic acid oxidase (ACO). To interfere with ethylene synthesis in plants we have cloned two ACS genes from ripening ‘Mclntosh’ apples. The gene showing the closest similarity to the ripening-related ACS gene in other fruits was used to make antisense constructs. ‘Royal Gala’ plants were transformed with these antisense constructs using an Agrobacterium-mediated transformation system. Transgenic Plants were propagated on antibiotic-containing agar, transferred to the green house for conditioning, and later to the field. Transgenic ‘Royal Gala’ Fruits which developed on these trees were evaluated for morphological characteristics, ethylene production, ACS activity and ripening parameters in the presence and absence of 1-methylcyclopropene (1-MCP) and ethylene. Data indicate down regulation of ethylene production and softening was achieved in some transgenic lines. 1-MCP (1 ppm, 24h, 0 0C) completely prevented the development of any ethylene treatment (50 ppm, 3h, 21 0C) did not affect the eventual onset and magnitude of ethylene formation in transgenic fruits.