Date of Award


Degree Type


Degree Name

Doctor of Philosophy


The initial bisexual spikelet primordium on the tassel and ear of maize matures into male and female spikelets. I performed a number of in vitro experiments with immature maize inflorescences to examine the regulation of flower development with plant growth regulators (PGRs). The ear meristems of Seneca-60 (S-60), and Ohio43 were cultured in Murashige and Skoog's basic nutrient liquid medium with and without different PGRs. The ears were classified into three Size Classes based on their initial lengths at the time of culture (A = 0.51-1.0, B = 1.1-1.5, C = 1.51-2.0 cm).;On basal medium, with no PGRs, a variety of flower types--bisexual, female, and abnormal (but no males) developed on all Size Classes of S-60 cultured ears. Kinetin (KN) at optimal levels applied to S-60 Class A ears stimulated stamens but inhibited gynoecial primordia. Gibberellic acid (GA3) alone or in the presence of KN, stimulated gynoecium growth and inhibited stamen primordia. Cell division in the inhibited organs in each case ceased within 30 h of explanting. The presence of indole acetic acid (IAA) alone or with KN promoted all flower types.;These differential developmental responses in the cultured flower organs of S-60 Class A ears occurred between 2 to 5 days of explantation. The irrevocable differentiation state of flower organs (either stamens or ovaries with silks) was achieved after 6 days of culture.;Further, I extracted newly synthesized polypeptides at different stages of in vivo developing S-60 tassel and ear flower organs. Similar polypeptides appeared on two dimensional gel fluorograms at all stages of flower development. Besides, six unique polypeptides were identified with the maturation of stamens (relative molecular weights 39,000; 94,000; and 36,000), and with the maturation of ovaries (relative molecular weights 41,000; 18,000; and 85,000). These unique polypeptides were also identified from the in vivo developing an1/an1 ear spikelet organs.



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