Abstract Detail

Pteridology

Hornych, Ondrej [1], Ferova, Alzbeta [1], Hori, Kiyotaka [2], Kosnar, Jiri [1], Ekrt, Libor [3].

Males are always ready: an experimental approach to the reproductive characteristics of sexual and apomict fern gametophytes.

Premise of the study Apomixis and hybridization are two essential and complementary factors in the evolution of plants, including ferns. Hybridization combines characteristics from different species, while apomixis conserves features within a lineage. When combined, these two features result in apo-sex hybrids. The factors leading to the formation of these hybrids are poorly understood in ferns. Methods We cultivated spores of 66 ferns (43 apomicts, 8 apomictic hybrids and 16 sexuals), focusing on Dryopteris (38 samples), and measured their development stages in vitro over the course of 16 weeks. We evaluated germination, lateral meristem formation rates as well as sexual expression and the production of sporophytes. We compared the ontogenetic patterns between the three groups – apomicts, sexuals and their hybrids. Key results The three groups formed antheridia but otherwise differed significantly in their gametophyte development (p<0.001). Sexual species created archegonia (85.7% of viable samples), but no sporophytes. Apomicts rarely created nonfunctional archegonia (8.3%) but generally produced sporophytes (75%). The sexually reproducing parent of one apo-sex hybrids formed about twice as meristic gametophytes as the apomictic parent, 38.6% vs. 19.7%, respectively. Apomictic and sexual species did not significantly differ in gametophyte development speed (p>0.206). Conclusions This study represents the most thorough comparison of gametangial development of sexual and apomictic ferns. Despite expectations, apomictic reproduction may not lead to a faster formation of sporophytes. Apomicts likely contribute the male gamete to the hybrid. The development patterns found in the parents of apo-sex hybrid indicate a possible stimulation of hybridization rates via antheridiogens. The hybrids inherit the apomictic reproductive strategy and are thus capable of self-perpetuation.

1 - University Of South Bohemia, Faculty Of Science, Department Of Botany, Branisovska 1760, Ceske Budejovice, CZ-37005, Czech Republic
2 - The Kochi Prefectural Makino Botanical Garden, 4200-6 Godaisan, Kochi, 781-8125, Japan
3 - University Of South Bohemia, Faculty Of Science, Department Of Botany, Branisovska 1760, Ceske Budejovice, JC, CZ-37005, Czech Republic

Keywords:
Dryopteris
fern
gametes
pteridophytes
apomixis
archegonia
antheridia
hybridization.

Presentation Type: Oral Paper
Session: PTR2, Pteridology II
Location: /
Date: Monday, July 19th, 2021
Time: 2:00 PM(EDT)
Number: PTR2003
Abstract ID:165
Candidate for Awards:Edgar T. Wherry award