Masters Theses

Date of Award

12-1987

Degree Type

Thesis

Degree Name

Master of Science

Major

Life Sciences

Major Professor

Donald K. Dougall

Committee Members

Beth C. Mullin, Otto Schwarz, Gary Stacey

Abstract

Information from previous studies suggests the existence of two classes of cells in wild carrot cultures, one accumulating and the other non-accumulating for anthocyanin, which are potentially reversible. The nature of the block in the low or non-anthocyanin accumulating phenotype is not known. The objective of this study was to further examine high- and low-accumulating wild carrot clones and subclones and determine the general location of the block in anthocyanin biosynthesis in the low-accumulating cultures. Preliminary experiments involved feeding coumarate, naringenin and dihydroquercetin (representing an early, middle and late intermediate, respectively, in anthocyanin biosynthesis) to the parental wild carrot line to determine the optimum concentration of each precursor that can be supplied to cultures and to confirm the ability of each precursor to result in a stimulation in anthocyanin accumulation. High- and low-yielding clones and subclones were then examined for their responsiveness to these intermediates. In general, low-accumulating clones/subclones with extremely low anthocyanin levels were nonresponsive to all three precursor feedings, while clones/subclones with the accumulating phenotype were able to respond to all three anthocyanin precursors. The level of response in anthocyanin content due to precursor feeding appears to be related to the Initial anthocyanin content of a culture, with those clones possessing the higher anthocyanin content displaying the greatest Increase In anthocyanin in response to Intermediates. In addition, microscopic examination of several high- and low-accumulating subclones revealed that they consist of a mixture of red (accumulating) and white (non-accumulating) cells and indicated a strong correlation between anthocyanin content and the % red or accumulating cells in the population. Together these observations suggest that the level of response to precursor feedings Is, as least in part, related to the % of red cells, or accumulating cells. In the population. It was concluded that the Impediment In anthocyanin biosynthesis in the non-accumulating phenotype Is located at a point beyond dihydroquercetin.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS