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Early inflorescence development in the grasses (Poaceae)
Elizabeth A Kellogg1, Paulo E A S Camara, Paula J Rudall
1Department of Biology, University of Missouri-St. Louis St. Louis, MO, USA.
Frontiers in Plant Science
|July 31, 2013
Summary
The grass inflorescence
Area of Science:
- Plant developmental biology
- Evolutionary botany
- Grass genetics
Background:
- The shoot apical meristem (SAM) in grasses controls inflorescence architecture and seed production.
- Leaf primordia exhibit distichous phyllotaxis (180° separation), while inflorescence branches typically show spiral phyllotaxis.
- The shift in phyllotaxis from spiral to distichous in the Pooideae subfamily is not well understood.
Purpose of the Study:
- To investigate the evolutionary origin of distichous inflorescence branching in the grass subfamily Pooideae.
- To determine the phyllotaxis of the inflorescence in Brachyelytrum, the sister genus to Pooideae.
- To describe the characteristics of two-ranked inflorescences in Pooideae and their evolutionary implications.
Main Methods:
- Phylogenetic analysis of grass species.
- Comparative morphological studies of inflorescence development.
- Examination of phyllotaxis patterns in Brachyelytrum and Pooideae species.
Main Results:
- Brachyelytrum, sister to Pooideae, displays spiral inflorescence phyllotaxis.
- The majority of Pooideae species exhibit two-ranked inflorescence phyllotaxis, not strictly distichous.
- Two-ranked inflorescences possess an undescribed developmental axis, and strictly distichous patterns evolved later within Pooideae.
Conclusions:
- The distichous inflorescence pattern in Pooideae likely did not originate at the base of the subfamily but evolved later.
- Two-ranked inflorescences represent a distinct developmental pattern in grasses, with implications for understanding inflorescence evolution.
- The developmental decision for meristem fate (branching vs. abortion) is independent of the observed phyllotaxis.
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