DOUST, ANDREW, N.L.* AND ELIZABETH, A. KELLOGG. Department of Biology, University of Missouri-St Louis, St Louis MO 63121. - Patterns of inflorescence development in Setaria (Panicoideae, Poaceae).
The development of the inflorescence in Setaria italica
(foxtail millet), S. verticillata, S. viridis, and S.
grisebachii was examined. The inflorescences of the different
species differed in numbers of orders of branching, with S.
italica having 2 or more orders as compared to one order in the
other three species. All species initiate spikelets paired with
bristles, but many of the spikelets are suppressed during development.
In S. grisebachii pairs of spikelets and bristles appear
together on the branches, in S. verticillata and S.
viridis a single spikelet at maturity is surrounded by a series of
bristles, and in S. italica three or four spikelets and at
least twice as many bristles appear on the primary branches.
Differences between the species appear early in development and have
the potential, along with density of branches in the spike, to be
major determinants of yield. The different mature morphologies of the
inflorescences are similar to various mutant phenotypes of maize, such
as ids1, ts6, and ra1 & 2, which raises
the prospect of using genes identified from maize to identify
differences in inflorescence morphology in a comparative manner across
species groups. The present study is a step towards relating advances
in model plant genetics to an understanding of natural morphological
differentiation in plants.
Key words: inflorescence development, inflorescence morphology, Poaceae, Setaria