Apomixis in St. John's wort: An overview and glimpse towards the future.

St. John’s wort (Hypericum perforatum L., 2n = 4x = 32) is a medicinal plant that produces pharmaceutically important metabolites with antidepressive, anticancer and antiviral activities. It is also regarded as a serious weed in many countries. Wild populations are composed of diploid sexual or polyploid (mostly tetraploid) pseudogamous facultative apomicts. Recent research has shown that H. perforatum is an attractive model system for the study of apomixis, as it is characterized by a relatively small genome size, a versatile mode of reproduction ranging from complete sexuality to nearly obligate apomixis, and a relatively short generation time. A better understanding of its reproductive and inheritance patterns is required to facilitate the identification of factors associated with apomixis, if these traits are to ever benefit agriculture. This paper reviews the cyto-embryological, molecular and ecological data which have been collected to elucidate apomixis in St. John’s wort, and includes an overview of the main tools which have been and are being used to investigate apospory, parthenogenesis and apomixis within this system.