Triploid Ginkgo production from interploidy crossings

Ginkgo biloba is a phylogenetically, ornamentally, culturally, and medicinally important representative of gymnosperms. This group exhibits an extremely low frequency of polyploids, in contrast to the frequent and economically valuable polyploids found in its sister group, the angiosperms. Recently, we found several polyploids among cultivated Ginkgo plants in Europe and North America. However, their use in breeding programs remains limited due to their young age and/or infertility. Here, we report the discovery of the first “flowering” tetraploid Ginkgo plant and describe the interploidy crossing experiments we conducted using pollen from this male tetraploid and several female diploids. These crossings yielded four triploid plants (2 n = 3x=36), which only originated from certain Ginkgo females and when ovules were protected from open pollination with normal diploids. Additionally, we also discovered a new spontaneous tetraploid seedling. Beyond documenting the fertility of Ginkgo tetraploids, our experiments suggest that interploidy crossing can be utilized to produce viable Ginkgo triploids. However, this process and its outcomes may depend on the genetic compatibility of the crossed plants and is yet not routine. Further research is needed to identify more fertile polyploids or genetically compatible plants to optimize this breeding strategy in the future. • Oldest-know Ginkgo tetraploid started to flower and produce viable pollen. • Crossing between the tetraploid and diploids resulted in viable triploid offspring. • Triploid Ginkgo shows promising growth for timber, leaves, and ornamental use. • Fertile polyploids and their cross-ability opens new avenues for Ginkgo breeding.