Thesis - Open Access
Master of Science (MS)
It is theoretically possible to culture any tissue from any plant or animal, but little work has been done on the major grain crops, especially Zea mays, because they are monocotyledons and present special problems in tissue culturing because of their slow growth. This thesis reports an attempt to grow and redifferentiate callus tissue of corn. The objectives of the research were: (1) to test the ability of different inbred and hybrid corn varieties to form callus and (2) to characterize the callus cell ultrastructure. Since so much is known about corn on the genetic level, it is appropriate to study the abilities of different genetic varieties to form callus and redifferentiate. The keys to differentiation are related to the genetic potential of the cell and to the cell environment. In the same environment different varieties should show variation in their ability to form callus and redifferentiate. The effects of growth regulating substances should be visible by examination of the cells and their organelles, the electron microscope is a useful tool in the investigation of growth regulator mode of action. It can supplement the commonly used biochemical methods and provide new information relating to the mechanisms of cellular differentiation. If corn plants could be regenerated from callus cells, several aspects of tissue culture would be of great significance for crop improvement. Since the stress of callusing may bring about variation in chromosome numbers the regenerated plantlets may have the same variation in chromosome numbers. These plants are valuable in developing new corn lines. The use of tissue culture would provide a much faster method of developing these lines than the field techniques now used. If the culture and redifferentiation requirements for diploid corn tissue are found, the requirements of haploid tissue will be similar. When a haploid tissue culture of corn is developed, it may be treated with a chemical like colchicine which causes chromosome doubling. The resultant diploid culture would be homozygous at all genetic loci. "Pure" inbreds are of course valuable. When crossed to other inbreds they produce offspring showing increased hybrid vigor. By developing corn callus cultures, the new experimental method of cell hybridization by protoplasmic fusion could be used. Existing barriers between corn and other species or genera would be overcome allowing fresh genetic material to be added to corn lines.
Library of Congress Subject Headings
Corn -- Breeding
Number of Pages
South Dakota State University
Johnson, Judy Winkler, "An Expression of Hybrid Vigor and a Characterization of Callus Tissue of Zea mays L." (1972). Electronic Theses and Dissertations. 4791.