The series for UBC Research Week is coming to a close soon. Connor’s helped assemble this entry:
Andrew Riseman, an Associate Professor in the Faculty of Land and Food Systems at UBC and Ornamental Plant Breeder at the UBC Botanical Garden, shares his research on the various means by which plants can prevent self-pollination.
These photographs were taken from a research project evaluating self incompatibility in the genus Staphylea. Self-incompatibility systems act in promoting outcrossing (i.e., increasing genetic diversity) by only allowing non-self pollen to complete fertilization. These systems can be morphological (e.g., imperfect flowers where male or female organs are absent), developmental (e.g., protandry when the anthers reach anthesis before the stigmatic surface is receptive), or genetic (e.g., gametophytic self- incompatibility (GSI) where pollen tube growth of only self-pollen is disrupted by pistil tissue). In Staphylea, a GSI system appears to be present. These images are from outcross pollinations (i.e., compatible) between two Staphylea holocarpa var. rosea accessions maintained at the UBC Botanical Garden. As expected from a compatible cross, pollen grains successfully germinate and penetrate the stigmatic surface (photo 1). Pollen tubes continue to grow through the style to the ovary with individual tubes reaching separate ovuals (photo 2). Once fertilization is complete, fruit containing the newly formed seeds are produced (photo 3). The fourth photo shows a Staphylea flower post-anther dehiscence.