This is an image of an Arabidopsis pistil (a female reproductive organ in flowering plants) being fertilized by pollen. When a pistil is pollinated, pollen grains elongate, becoming "pollen tubes." When a pollen tube encounters an unfertilized egg cell in the pistil, it will fertilize it to initiate seed development.

I wanted to see if a rapidly evolving peptide gene was expressed in pollen tubes, so I performed RNA-FISH to visualize it in flowers that had been recently pollinated. The RNA-FISH signal is green, and here it is evident that the gene is expressed in pollen tubes. The blue signal labels DNA in all cells.

I hypothesize that rapidly evolving peptides in pollen tubes promote interspecies fertilization.