Molecular analysis of NOZZLE, a gene involved in pattern formation and early sporogenesis during sex organ development in Arabidopsis thaliana

Sexual reproduction is a salient aspect of plants, and elaborate structures , such as the flowers of angiosperms, have evolved that aid in this process . Within the flower the corresponding sex organs, the anther and the ovule, form the male and female sporangia, the pollen sac and the nucellus, respe ctively. However, despite their central role for sexual reproduction little is known about the mechanisms that control the establishment of these impo rtant structures. Here we present the identification and molecular characte rization of the NOZZLE (NZZ) gene in the flowering plant Arabidopsis thalia na. In several nzz mutants the nucellus and the pollen sac fail to form. It indicates that NZZ plays an early and central role in the development of b oth types of sporangia and that the mechanisms controlling these processes share a crucial factor. In addition, NZZ may have an early function during male and female sporogenesis as well. The evolutionary aspects of these fin dings are discussed. NZZ encodes a putative protein of unknown function. Ho wever, based on sequence analysis we speculate that NZZ is a nuclear protei n and possibly a transcription factor.