Adaptation of the seed reproduction system to conditions of Maritime Antarctic in Deschampsia antarctica E. Desv.

Resumo

Deschampsia antarctica3 E. Desv. is one of the two flowering plants that, along with Colobanthus quitensis (Kunth) Bartl., was able to settle the ice-free areas of Antarctica. In order to identify the possible adaptations of the D. antarctica reproductive system to adverse environmental conditions, comparative cytoembryological analysis of plants of this species growing on the Antarctic Peninsula with plants of the closely related species D. beringensis Hult. from the Kamchatka Peninsula was conducted. It was found that both species are characterized by sexual mode of reproduction, equal size of pollen grains (25.5 ± 2.2 and 26.2 ± 1.9 μm, respectively), same features of the embryo sac structure, and emryo- and endospermogenesis. Interspecies differences have been found in mature embryo sac size (326.8 ± 12.8 and 161.7 ± 10.4 μm), pollen sterility percentage (86.1 ± 8.9 and 35.3 ± 9.2%), and quantity of pollen in the anthers (140 ± 15.3 and 1578 ± 88.6). Possible causes and significance of these differences are discussed. No unique adaptations of seed reproduction system that are inherent exclusively to D. antarctica were found. The D. antarctica reproduction strategy is based on the combination of autogamy (and its extreme form cleistogamy) with production of excess pollen quantity for its mode of pollination.