Submitted to: International Symposium on Biotechnology of Temperate Fruit Crops and Tropical Species
Publication Type: Abstract only
Publication Acceptance Date: 8/30/2005
Publication Date: 10/12/2005
Citation: Callahan, A.M., Scorza, R. 2005. Effects of a peach antisense acc oxidase gene on plum fruit quality. International Symposium on Biotechnology of Temperate Fruit Crops and Tropical Species, Daytona Beach, FL, October 10-14, 2006. Interpretive Summary:
Technical Abstract: Stone fruit are harvested while still firm in order to arrive in the grocery store intact. A goal of our program is to determine if delaying the production of ethylene in ripening fruit will develop more tree-ripened flavors, while still remaining firm. Plum hypocotyls were transformed with an antisense construct of a peach ACC oxidase gene (responsible for the last step in ethylene formation) that was driven by the 35S promoter. Eighteen lines were derived from four genetically different hypocotyls from 'Bluebyrd' and three from 'Stanley'. DNA blot data indicated that the majority of these had a single insertion of the peach antisense ACO gene. Wound ethylene responses were measured on the seedlings in the greenhouse and after one year of growth in the field. Most of the transgenic lines had reduced ethylene responses, while a few had increased ethylene responses. Fruit quality data, consisting of firmness, color, date of ripening, brix, size and titratable acids, as well as ethylene rates, were measured for two years on the fruiting lines. Analyses of the data suggested that in some transgenic lines, ethylene production was delayed relative to the 'Bluebyrd' parental line, and softening was also delayed. Sugar levels were lower in most of those, while color and size were not affected. The correlation of levels of plum ACO mRNA with phenotypes are currently being examined.