Molecular Cloning and Characterization of Lipoxygenase Genes in Watermelon

Lipoxygenases (LOX) are the enzymes of the oxidoreductase group that catalyze the oxidation of cis, cis 1,4-pentadiene group unsaturated fatty acids. Lipoxygenases peroxidate the normal substrates of unsaturated fatty acids, while simultaneously causing indirect oxidation (co-oxidation) of xanthophylls and lutein, especially carotenoids and thus causing discoloration. Lipid peroxidation is generally accepted as an indicator of membrane degradation or loss of function. Studies show that the changes in membrane lipids play an important role in the rapid softening and deterioration of fruits and vegetables. In this study, the isolation and characterization of lipoxygenase genes which are very important in terms of watermelon fruit and which are effective in preventing the bad taste, aroma and discoloration and lipid peroxidation have been made. In this study, lipoxygenase genes were identified, cloned and characterized from watermelon obtained from Faculty of Agriculture Department of Horticulture. For this purpose, previously characterized lipoxygenase gene sequences in the gene bank were obtained and the portions of these sequences that did not change between species were determined. Primers were prepared based on these fractions and subjected to the PCR reaction with watermelon cDNA. The resulting cDNA fragment was cloned and sequenced. After the determination of similarity with lipoxygenase genes, 3' and 5' ends were completed by RACE analysis. The resulting gene fragments were cloned and sequenced and proved to be lipoxygenases.