As new species evolve during incipient speciation, different crossing barriers are formed, which prevent the formation of potentially unviable or sterile hybrid offspring. It has been considered that these barriers are weak at the beginning of the split of two species, still allowing the formation of hybrids, albeit this may be rare. Later, stronger barriers evolve that prevent any crossing and the two species are reproductively isolated.
We study how speciation emerges, looking at the origin of reproductive barriers. As tool we use two closely related species, Arabidopsis thaliana and Arabidopsis lyrata, where reproductive barriers are still in formation. Depending on the A.thaliana accession, A.lyrata pollen is recognized with a variable degree of success (between 10% and 90%). If recognition does not occur, the pollen tube (PT) is not properly received, keeps growing inside the ovule, and fertilization fails. This recognition step takes place in the cells at the contact point between the embryo sac and PT, the synergids, and can be considered the point of emergence of a first reproductive barrier. Genes involved in reproductive barriers are expected to show rapid divergence.
The work focuses on the regulation of the genes found to be important for interspecific PT recognition by the female gametophyte, as well as the molecular characterization of the recognition mechanism.
The proposed research project main objectives are:
1. Characterization of the newly discovered gene: generating additional alleles (CRISPR-Cas9), addressing redundancy in synergids, manipulation by ectopic expression
2. Identification of the promoter region of discovered gene from different Arabidopsis species
3. Identification of the factors regulating discovered gene in A. thaliana
4. Training, active dissemination, publication
