Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Studies on the in vitro culture of immature tassels of Zea mays are reported. These include, the development of a suitable medium and appropriate physical conditions which allow meiosis, microsporogenesis and pollen maturation to occur in cultured cv. Oh43 tassels, and some physiological and nutritional aspects. Sucrose served mainly as an energy source and not as an osmoticum for cultured tassels during the first 15 d. After 15 d of culture, tassels were shown to become "autotrophic" though sucrose seemed to be necessary for differentiation of normal spikelets.;Most single amino acid additions were either ineffective or inhibitory, though arginine, lysine, valine and proline were stimulatory. A mixture of these four stimulatory amino acids at their optimum concentrations duplicated the effect of an optimum concentration of casein hydrolysate.;For the first time, the production of germinable and viable pollen from cultured flower primordia was demonstrated. Under optimal conditions, normal spikelets from cultured tassels extruded anthers, which dehisced and released mature, normal pollen. This pollen germinated on agar and on receptive silks and also fertilized ovules to produce mature, viable kernels which grew into mature, fertile genetically true plants. These plants were similar in most respects to normal plants as shown by morphological and cytological analyses, and gel electrophoresis.;Tassel culture was also used to test the potential reversion of two genic male steriles (ms14 and ms24) with different plant growth regulators. None of the regulators used reverted either mutant to produce fertile pollen at the concentrations and forms applied.;Now that a significant component of the life cycle of maize, from stamen initiation to production of normal, viable pollen, can be carried out in vitro, a number of analyses and manipulations are possible for both basic and applied research. The possible importance of tassel culture for potential applications in plant breeding and biotechnology is recognized.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.