Uncovering the inflorescence evolution of Eleusininae (Cynodonteae: Chloridoideae: Poaceae)
MUCHUT S.; REUTEMANN AG; PILATTI V; UBERTI MANASERO N; VEGETTI AC; REINHEIMER R
BOTANICAL JOURNAL OF THE LINNEAN SOCIETY
WILEY-BLACKWELL PUBLISHING, INC
Lugar: Londres; Año: 2019
Inflorescence forms displayed by grasses lead to a general assumption that their evolution is random. We reconstructed the ancestral inflorescence of subtribe Eleusininae and outlined possible evolutionary pathways to test the hypothesis of non-directionality in grass inflorescence evolution and the hypothesis of an evolutionary direction from complex to simpler inflorescence architectures in this lineage. By studying early stages of inflorescence and spikelet development, we investigated ontogenetic changes that may correlate with evolutionary pathways identified. The approach presented here indicates that the current diversity of inflorescences found in Eleusininae is likely a result of two evolutionary distinct pathways. The main path involves a multi-staged course with shortening of main axis internodes first, followed by a decrease in number of primary branches and florets per spikelet. We postulate that reduced elongation of the internodes may affect the apical and axillary meristems performance which in turns promotes a decrease in the number of primary branches and floret per spikelet. Current diversity of Eleusininae inflorescences may be a consequence of a reductive evolution. We found that the evolutionary directionality of Eleusininae inflorescence may be associated to developmental events that affected inflorescence morphology at early stages.