RNase-based Self-incompatibility in Lysimachia monelli (Primulaceae)

Most flowering plant species simultaneously express male and female function. They may be potentially self-fertilized because an individual's stigma often receives its own pollen. Nevertheless, one-half of angiosperms are self-incompatible---they cannot self-fertilize. Such individuals possess a genetic mechanism that helps sort incoming pollen grains, rejecting all those that match a specific genomic region. Many self-incompatibility mechanisms exist, but one is particularly widespread. It uses ribonucleases, proteins that cleave RNA, to differentially arrest the growth of self-pollen tubes. We find that this mechanism operates in a member of the primrose family, Lysimachia monelli. Understanding the distribution of this phenomenon is critical for determining the causes and consequences of variation in plant mating patterns. It is also broadly useful in a variety of applications, including plant breeding and conservation.