Mature pollen consists of the vegetative cell and the two plasma membrane-bound sperm cells enclosed within its cytoplasm. In contact with a receptive stigma, pollen germinates producing a pollen tube, which will grow through the pistil until it reaches the embryo sac.

Here the two sperm cells will be released, one fertilizing the egg cell and the other the central cell. Preferential fertilization, in which each sperm cell is predestined to fuse with either the egg cell or the central cell, can be found in a limited number of angiosperms with dimorphic sperm cells.

Whether preferential fertilization also exists in angiosperms with isomorphic sperm cells (e.g. Arabidopsis thaliana) has been a long-standing question. The current consensus based on mutant analyses and semi in vivo experiments is that no such preferential fertilization exists in Arabidopsis.

In this project, we are addressing the question if gene expression levels differ in isomorphic sperm cell pairs and if such differences could lead to preferential fertilization.