|M.Sc Student||Bhasteker Dorit|
|Subject||Mapping of Traits and Identification of Genes that are|
Involved in Determination of Color of Flesh and
Skin in Melon Fruits
|Department||Department of Biology||Supervisors||Professor Emeritus Shimon Gepstein|
|Dr. Nurit Katzir|
|Dr. Joseph Burger|
There are major traits which determine the commercial value of melons (Cucumis melo L), among them is color. In order to study color change during ripening of melon, two cultivars were chosen: Tam Dew (green flesh) and Dulce (orange flesh). Tam Dew and Dulce were crossed in order to create the first (F1) and the second (F2) offspring generations. Segregation analysis revealed that the color of the immature rind and the color of the mature flesh are determined by single dominant genes. In addition, traits such as mature rind color, stripes and net were found to be determined by more than one gene.
The flesh color change during melon fruit ripening is mainly due to β-carotene accumulation, whereas the color change of the rind is mainly due to chlorophyll degradation. Chlorophyll degradation exposes carotenoids and flavonoids, leading to change of the rind color. There is a tentative indication of the presence of flavonoids in the melon rind. The expression of genes associated with carotenoid biosynthesis was found to increase during fruit ripening in both green flesh and orange flesh cultivars. A melon genetic linkage map based on the F2 population was created. The map consisted of sixty SSR markers distributed among 12 linkage groups. Fifteen markers were derived from genes, among them three genes of the ethylene pathway. Some of the genes and markers were mapped for the first time, including geranylgeranyl reductase, ACC oxidase-3 and invertase. In addition, the trait of flesh color was mapped.