Molecular Control of Male Germ Line Initiation and Fertilization

Sexual reproduction is one of the important events in the life cycle of flowering plants. Isolation of male gamete (generative and sperm cell) specific genes and studying their role in sperm egg interactions during fertilization is lilyone of the major goals of the group. This research is at the international forefront of this field. Our group is the first to identify male gamete specific genes and promoters in flowering plants. We have discovered a genetic switch significant for male germ line development in plants. In plants, the male germ lineage arises from cells of a previously somatic lineage, and germ line initiation involves a novel mechanism: repression of germ line genes in cells that are not destined to become germ cells.GC This genetic switch, which we have identified from the lily, is a transcription factor called germ line-restrictive silencing factor (GRSF). We published this finding in Science (Haerizadeh et al 2006), where we proposed that GRSF plays a pivotal role in delineating plant reproduction by preventing the expression of germ cell specific genes in somatic cells. We have also shown that GRSF is ubiquitous in non germ cells and is absent from germ cells. We now aim to unravel the mechanism by which this genetic switch functions to repress somatic genes during plant growth, and what triggers this switch to derepress the germ line transcriptional program and turn on during the male germ line linage formation. An understanding of the key regulatory mechanism at the gene level is needed in order to develop new strategies for enhancing agricultural food production.