TcCRP1 as a pollen-tube attractant in Torenia

A key factor of pollen-tube attraction to an ovule is that it is species-specific, and recently a family of secreted proteins with attractant properties has been discovered in Torenia fournieri. Kanaoka et al. study TcCRP1, an orthologous gene of TfCRP1 from T. concolor, and find it is expressed predominantly in the synergid cell. The gene product attracts pollen tubes of T. concolor in a concentration-dependent manner, but attracts far fewer tubes from pollen of T. fournieri. The results indicate that this class of CRP proteins is a common pollen-tube attractant in Torenia species and that their sequence diversity is important for species-specific pollen-tube attraction.