Differences in pollen viability in relation to different deceptive pollination strategies in Mediterranean orchids

To date, current research involving pollen viability has been evaluated in a relatively lownumber of orchid species. In the present study, we focused on five related Mediterranean orchid genera(Anacamptis, Orchis, Dactylorhiza, Ophrys and Serapias) that are characterized by different types of deceptivepollination.The in vitro germination ability of increasingly aged pollinaria of eight food-, seven sexually and twoshelter-deceptive species was evaluated. Pollination experiments on two food-, one sexually and one shelterdeceptivespecies were also performed and the percentage of embryonate seeds derived from the increasinglyaged pollinaria was checked.All of the examined species showed long-term viabilities (¼50 % pollen tube growth) that rangedfrom 8 to 35 d. Species with the same deceptive pollination strategies exhibited the same pollen viability trends.Interestingly, pollen viabilities of species groups with different deception types have shown significant differences,with sexually and shelter- deceptive species exhibiting a shorter life span than food-deceptive species.†Conclusions This study confirms the prolonged germination and fertilization capacities of orchid pollinaria, andto our knowledge is the first report demonstrating a clear relationship between pollen viability and pollinationsystem. It is proposed that this relationship is attributed to the different types of reproductive barriers, pre- orpost-zygotic, that characterixe Ophrys and Serapias and the food-deceptive species, respectively.