Evolution of Parallel Spindles Like genes in plants and highlight of unique domain architecture

Background Polyploidy has long been recognized as playing an important role in plant evolution. In flowering plants, the major route of polyploidization is suggested to be sexual through gametes with somatic chromosome number (2n). Parallel Spindle1 gene in Arabidopsis thaliana (AtPS1) was recently demonstrated to control spindle orientation in the 2nd division of meiosis and, when mutated, to induce 2n pollen. Interestingly, AtPS1 encodes a protein with a FHA domain and PINc domain putatively involved in RNA decay (i.e. Nonsense Mediated mRNA Decay). In potato, 2n pollen depending on parallel spindles was described long time ago but the responsible gene has never been isolated. The knowledge derived from AtPS1 as well as the availability of genome sequences makes it possible to isolate potato PSLike (PSL) and to highlight the evolution of PSL family in plants.