Biosystematic studies on the mountain plant Gentiana lutea L. reveal variability in reproductive traits among subspecies

Abstract

Background: Taxonomic analysis provides a basic understanding for taxon identification and contributes to preliminary information for several branches of applied biology, while studies on reproductive strategies and plant fitness are essential to interpret population status and dynamics.

Aims: We tested the reliability of diagnostic characters for identification and to characterise sexual resource allocation, the breeding system and seed predation among subspecies of Gentiana lutea.

Methods: We analysed morphological characters in 70 herbarium specimens. In five natural populations we counted pollen and ovule numbers, assessed reproductive output after pollination treatments and evaluated pre-dispersal predation.

Results: Taxonomic traits previously indicated as diagnostic were not sufficient to discriminate among subspecies. The pollen number and pollen:ovule (P:O) ratio varied strongly among subspecies; self-pollinated flowers produced a significantly lower number of seeds than open-pollinated flowers. Retention of empty fruits and high levels of pre-dispersal seed predation were observed in every case.

Conclusions: The variation of P:O ratios among subspecies suggests different efficiency in pollen transfer. The species is self-compatible, nevertheless all subspecies require pollen vectors to enhance cross pollination and viable seed production. Fruit retention may have evolved as a strategy to reduce predation, ensuring higher plant fitness.

Keywords:

• breeding system
• fruit retention
• mountain species
• plant fitness
• seed predation
• sex allocation
• taxonomic traits

Acknowledgements

We thank Silvia Crema, Valentina Lucchetta, Michela Albertini and Valentina Manca for help during field-work, Nicola Sitta and Alessandro Alessandrini for helpful information on Mt. Grande population, Annalisa Managlia and Umberto Mossetti for technical assistance, Giovanni Cristofolini for scientific support and valuable suggestions. We also thank Parco Nazionale dei Monti Sibillini for permitting field investigations.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

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Additional information

Funding

This work was supported by the Italian Ministry of Education, University and Scientific Research within the frame of the project PRIN 2008 (Progetti di Ricerca di Interesse Nazionale) to MG. MR was supported by a Ph.D. Grant from the University of Bologna.

Notes on contributors

Martina Rossi

Martina Rossi collected and analysed data for this work during her Ph.D.; she is currently a postdoctoral researcher working on population genetics and on the development of new molecular markers; other research topics include plant breeding and germplasm conservation.

Alessandro Fisogni

Alessandro Fisogni is a research fellow, working on a European Union project focused on plant-pollinator interactions and biodiversity conservation.

Marta Galloni

Marta Galloni is a research associate; her research interests include plant reproductive ecology, plant-pollinator interactions and conservation biology.