Polyembryonic or Apomictic Seeds Enable Fig Trees to Establish New Populations Without Their Pollinating Wasps, a...

Fig-wasp coevolution has been extensively studied as a fascinating case of extreme plant-insect codiversification, yet little is known about how fig trees reproduce without pollinating fig wasps. This study provides direct evidence that fig trees sustain their populations by producing polyploid and polyembryonic seeds through apomixis without fig wasp pollination. We report herein that the seeds of unpollinated Ficus gasparriniana are derived from adventitious embryos formed in the nucellar tissues and show sporophytic apomixis. Apomixis is an important reproductive mode of F. gasparriniana, which has diverse pedigree sources. Flow cytometry combined with chromosome counting and short tandem repeat typing results showed that apomixis in F. gasparriniana was closely related to polyploidy, suggesting that sexual reproduction occurred at the diploid level and apomixis occurred at the polyploid level. Thus, other polyploid Ficus species may also exhibit apomictic reproduction. This study provides essential data for advancing research on apomixis in Ficus and its role in the coevolution of fig-wasp mutualism.