9307733 Helentjaris Most of the natural variation we see between individuals of any species is under the control of multiple genes. Use of molecular markers has begun to identify major loci involved in this variation. Height in maize is chosen for study as there are ample data describing major quantitative factors, excellent molecular tools for this organism, several candidate genes which might contribute to this variation, and physiological correlations between these candidate genes and the quantitative variation. The general approach would be to use isogenic lines for regions containing obvious candidate genes to reduce the complexity of the variation for height and then to determine precisely what is the contribution of individual genes to the natural quantitative variation within maize genotypes. Clones for these genes will be obtained. Variation within the coding region, will be studied using molecular techniques to identify whether gene product function or overall expression of the gene are affected. Efforts will then be directed towards determining what aspects of this natural genic variation actually contribute to the variation in height observed in these maize lines. The effects of environmental influences upon quantitative variation will also be studied. The overall goal of this program is to develop an experimental system which bring together elements of quantitative, Mendelian, and molecular genetics to enhance our understanding of the functional basis for natural quantitative variation, and to develop strategies for translating positional information on major genes into practical methods for their isolation. %%% As many of our economical ly most important traits in domesticated plants and animals (as well as in humans and non domesticated species) possess a complex inheritance, this approach will help to lay the ground work for more improved approaches in understanding the genetic basis of inheritance, and improved breeding strategies for domestic species using either traditional or molecular strategies.
