Multiscale diversity of an Arabidopsis pollen killer reveals its evolutionary history

Certain genetic elements are said to be selfish, as they favor their own transmission to the progeny during reproduction. They are very common in fungi, plants and animals alike, and each consists of two or three specific genes. In so-called "gamete-killers", one allele cause the death of gametes that do not carry it. These phenomena are of great interest, not only for understanding the mechanisms of evolution and speciation, but also, for example, for devising strategies to control invasive populations. In plants, only a few have so far been deciphered to determine the genes responsible.

A pollen killer was identified in a cross between two distant natural accessions of Arabidopsis thaliana. It involves three genetically linked genes: two are required to produce a poison and the third produces the antidote. The toxicity is pollen-specific and involves the mitochondria. The sequences of the proteins encoded by these genes reveal characteristics essential to their function. Analysis of over 700 worldwide accessions of A. thaliana shows that the locus is subject to major structural rearrangements and gene copy number variation, and sequence analysis has provided a scenario for the emergence of this pollen killer in the species. In addition, its presence in several local populations will make it possible to study the evolution of a killer pollen in the wild. Further studies will help to document the dynamics of a pollen killer in natural populations, thus informing theoretical and applied studies in evolutionary biology. They may also contribute to the societal debate on new types of segregation distorters, proposed for weed control or genetic rescue of endangered species.

These results underline that Arabidopsis, originally primarily a functional biology model, is also a valuable model for conducting population biology studies, thanks to hundreds of genotypes collected from numerous populations at different scales. With this in mind, the IJPB's "Plant Observatory - Versailles Arabidopsis Stock Center" plateform  PO-VASC will soon be hosting a set of natural French accessions collected at national, regional and local levels, which will be made available to the international scientific community. The availability of genomic sequences and the ecological characterization of their native habitats add considerable value to these resources.


Research developed at the Institute Jean-Pierre Bourgin for Plant Sciences.