Branching
Genetic
and Environmental Control of Vegetative Architecture in
Grasses
Vegetative
branching patterns in grasses are controlled both by genetic
and environmental factors. In weedy grasses like green
millet, the ability to tailor branching patterns to changing
environmental stimuli is an important fitness attribute, as
each branch that is produced will bear an inflorescence. Two
main branching modalities are distinguishable; tillering,
where branches are from produced from nodes at the base of
the plant, and may produce adventious roots themselves, and
axillary branching, where branches initiate in the axils of
leaves on each tiller. These two branching modalities are
distinguishable in Setaria
and many
other grasses because tillers are produced early in the life
cycle of the plant, whereas axillary branches appear to grow
out only after the tillers start to develop terminal
inflorescences. In contrast, during domestication, the
ability to respond to environmental stimuli is reduced or
lost, and most axillary branching is curtailed. This is the
case for foxtail millet and for other domesticated crops such
as maize and rice. I am examining the effects of density and
shading on branching patterns and on expression of major
branching genes in green and foxtail millet. I suspect that
the annual weedy habit has evolved numerous times in the
grasses, and I will be searching for shared developmental and
genetic changes in phylogenetically independent evolution
events in Pennisetum
and
Cenchrus.
Collaborators: Katrien Devos, University of Georgia, Athens;
Bob Schmidt, University of California at San Diego.
