The overall goal of the work described in this proposal is to understand how plant cells communicate with one another. To study this, this investigator analyzes the interactions that must take place between the male and female reproductive systems in order for fertilization to take place successfully. These encompass many different interactions which are required to control such diverse processes as the transfer of water from the stigma to the pollen grain, the acquisition of polarity by the pollen grain and the guidance of the growing pollen tube to an individual ovule. This investigator has undertaken a genetic approach to this problem, identifying mutations which result in sterility but are not due to the altered morphology of the reproductive system. He has identified one major class of male sterile mutants which fail to be recognized by the stigma and appear to be deficient in the production of long chain lipid species. He has also identified numerous mutations which alter the development of the ovules and has used these to determine that the haploid embryo sac contained within the ovule is essential for the proper guidance of the pollen tubes within the ovary. Experiments are proposed to extend the characterization of these mutations as well as to identify new mutations, including those which are active in the haploid phase of the plant life cycle. Specific objectives for this granting period are: (1) to identify as many genes as possible which are specifically involved in the control of the growth and development; and (2) to characterize the functions of the genes already identified genetically in the reproductive process by an analysis of their phenotypes.
