Currently the breeding of desirable traits in orchid flowers is a lengthy and unpredictable process. A shortened breeding time and a more direct method of introducing specific genetic characteristics could be achieved if more information were available on the specific genes responsible for flower characteristics. In order to identify some of these genes, the genetic relationships between a hybrid, Dendrobium Gatton 'Sunray', and the parent species bred to produce it, D. chrysotoxum Lindley and D. pu/che//um Lindley were examined.Ball State UniversityMuncie, IN 47306These results were supported by Restriction Fragment Length Polymorphisms (RFLPs) observed following amplification of the Internal Transcribed Spacer (ITS) regions of the rDNAs.In order to clone genes responsible for specific flower characteristics, mRNA differential display was performed using total RNA isolated from the leaves, immature flowers, and mature flowers of the hybrid orchid and its two parents. Bands unique to D. Gatton 'Sunray' flower tissue, which were common to the hybrid and a single parent, were excised from a denaturing acrylamide gel. Four of the bands, which represented expressed genes determining inherited flower characteristics, were re-amplified, cloned, and three were sequenced. Partial sequence information obtained for two of the clones was used to search the GenBank database for homologous genes. One of the clones had sequence homology to plant 26S ribosomal genes and the other clone was homologous to sequences encoding regulatory proteins active during development (for example, the human retinoblastoma susceptibility gene or the Caenorhabditis e/egans cosmid R06F6 containing a serine/threonine protein kinase gene). / Department of Biology