DOUST, ANDREW N* and ELIZABETH A KELLOGG. University of Missouri-St Louis, Missouri. - Integrating phylogeny, developmental morphology and genetics: a case study of inflorescence evolution in the ‘bristle grass’ clade (Panicoideae; Poaceae).
Our studies in the grass family Poaceae have concentrated on
understanding diversity in inflorescence morphology. We have focused
on the analysis of inflorescence evolution in the panicoid ‘bristle
grass’ clade (including Setaria, Pennisetum and
Cenchrus), as an example of the way in which molecular
phylogenetic hypotheses can be combined with developmental and genetic
data to understand morphological evolution. Analysis of developmental
morphology with phylogenies derived from molecular data sets has
enabled us to identify a small number of parameters that can control
morphological diversification. These include numbers of orders of
branching, numbers of primordia produced on each branch, and timing
and amount of branch axis elongation. Changes in these characters
occur numerous times throughout the phylogeny, suggesting that only
minor changes in a few genes are required to change inflorescence
morphologies. We are testing this hypothesis by a quantitative trait
loci (QTL) analysis of a Setaria italica by S. viridis
cross. Preliminary results indicate that numbers of primary branches
and length of the inflorescence are controlled by only a few genes, as
predicted.
Key words: developmental morphology, inflorescence evolution, phylogeny, Poaceae, quantitative trait loci (QTL) analysis, Setaria