Location: Crop Diseases, Pests and Genetics
Title: Development of table and raisin grapes with high anthocyanins using a leaf disk assay. Authors
Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: November 15, 2010
Publication Date: N/A
Interpretive Summary: Anthocyanins are considered an excellent source of antioxidant phytochemicals for health benefits. The majority of wine, table and raisin grapes only have anthocyanins in their skin when the fruit is colored. Anthocyanin content of grapes would be increased if their flesh also contained anthocyanins. A program to increase the health benefits of grapes has been started at the USDA/ARS laboratory, Parlier, CA. A red flesh wine grape was hybridized with a seedless red skin table grape. The seedlings segregated in the expected 1 white: 1 colored skin ratio and in a 1 clear: 1 red flesh ratio for colored berries. When red flesh individuals were hybridized back to either seedless table or raisin grapes, their progeny segregated for skin and flesh color. One red flesh parent gave an unexpectedly high percentage(>80%) of red flesh progeny. Leaf disks were taken from young seedlings 6” tall in the greenhouse to predict flesh color. The leaf disks developed red color when placed in a 10% sucrose solution for 5-10 days. The amount of red development in the leaf disks generally correlated with flesh color of the fruit. Thirty percent of the progeny were identified as having clear flesh and could be discarded before planting in the field. The leaf disk assay increases the efficiency of the breeding program and speeds up the development of red flesh seedless table and raisin grape cultivars.
Technical Abstract: Anthocyanins are considered an excellent source of antioxidant phytochemicals for health benefits. The majority of wine, table and raisin grapes have anthocyanins only in their colored skin. Anthocyanin content of grapes would be increased if their flesh also contained anthocyanins. C33-30, a seedless female flowered table grape with red skin and clear flesh berries was hybridized with Rubired wine grape which has black skin and red flesh berries. The F1 progeny segregated in a 3 colored:1 white skin and 1 red:1 clear flesh ratio for colored berries. The seedling expressing the highest level of anthocyanin in the flesh and skin was similar to Rubired. Seven modified backcross families were created by crossing red flesh seeded F1 selections with seedless red skin table or white skin raisin grapes. Skin color segregated as a single dominant gene as expected. One red flesh parent was heterozygous for skin color and the rest were homozygous. Only seedlings with colored skin had red flesh. Flesh color segregated as a 1 red:1 clear in three of the families or in a 2:1 ratio or higher in four families. One red flesh parent produced an abnormally high percentage (>80%) of red flesh seedlings. Leaf color in the leaf disk assay correlated well with flesh color in the F1 family. Seedlings that developed 0 to 20% anthocyanin in the leaf disk assay had clear flesh with white, red or black skin (32% of BC1 population). However 19% of red flesh seedlings would have been discarded using this selection criteria. Part of this discrepancy is due to the fact that leaves taken to early in their development from the greenhouse did not develop anthocyanin.