A SINGLE INSERTION OF ACC OXIDASE GENE IN ANTISENSE ORIENTATION EXTENDS THE SHELF LIFE IN MUSKMELON 'GALIA' HYBRID PARENTAL LINE (CUCUMIS MELO L. VAR. RETICULATUS SER.)
Galia muskmelon is an Israeli melon hybrid, which has been the mainstay in much of the European market for more than 30 years. Galia melons are harvested near peak maturity, which limits shelf life to two weeks or less. The male parental line of Galia was transformed with the ACC oxidase gene in antisense orientation. A postharvest evaluation of T0 fruits from two completely diploid independent transgenic lines is described herein. Explants were transformed using Agrobacterium tumefaciens strain ABI, which contained a vector pCmACO1-AS plasmid, bearing an antisense gene of CMACO-1 and the CP4 syn gene (glyphosate-tolerance). Both CMACO-1 and CP4 syn genes were assessed by a polymerase chain reaction method. Flow cytometry analysis was performed to determine plant ploidy level of primary transformants. Two completely diploid independent transgenic lines were obtained, which were named TGM-AS-1 and TGM-AS-2. Southern blot and segregation analyses in the T1 generation determined that each independent transgenic line had one single insertion of the transgene. Several postharvest parameters were evaluated in transgenic (TGM-AS) and wild type (WT) fruits. WT fruits were harvested at 37, 42 and 50 days after pollination (DAP), whereas TGM-AS fruits were harvested at 42, 50 and 56 DAP. The harvest of TGM-AS fruits was delayed since they ripened slower than WT. Fruit weight, length, width, soluble solids, titratable acidity, pH, firmness, flesh thickness, seed cavity size and seed number parameters were not significantly different between the two genotypes at 42 and 50 DAP. ACC oxidase activity from 42 DAP TGM-AS fruits was three times less than WT fruits. Likewise, ethylene production from 42 DAP TGM-AS fruits was reduced 80% compared to WT. TGM-AS T0 Galia male parental line fruits had a delayed fruit ripening process by up to 12 days compared with WT fruits.
Nunez-Palenius, H.G., Klee, H.J., Huber, D.J. and Cantliffe, D.J. (2007). A SINGLE INSERTION OF ACC OXIDASE GENE IN ANTISENSE ORIENTATION EXTENDS THE SHELF LIFE IN MUSKMELON 'GALIA' HYBRID PARENTAL LINE (CUCUMIS MELO L. VAR. RETICULATUS SER.). Acta Hortic. 731, 421-426
ethylene, organogenesis, plant tissue culture, Agrobacterium, greenhouse, GUS gene, ripening