Background: before Arabidopsis became
the model-of-choice for plant development, there was corn
(Zea mays). Maize remains among the most-studied
of all plant species, in part for economic reasons but
also because of basic problems of plant evolution associated
with development of the maize tassel and especially the
monstrous maize ear. Prior to this work the morphology
of tassel and ear development already had been well-documented
by Bonnett (1953). In addition, spikelet development in
both ears and tassels was known to consist of many sequential
steps with several of the genes controlling these steps
already identified (Coe and Neuffer, 1977). In this paper,
the authors examined genetic factors affecting the development
of clonal sectors of cells within these organs.
Their
results confirmed that both the tassel and ear have a polyclonic
origin and arise from a small group of embryonic initials
that become canalized as development proceeds. This process
of progressively restrictive determination, they suggested,
was comparable to the process of compartmentalization that
had recently been described for the imaginal disks of Drosophila.
Their results also supported the idea that this canalization
consists of a series of developmental switch points. Up
to a point, the fate of a particular primordium is indeterminate,
but once that point is reached, development proceeds along
one of two (or more) pathways dependent upon the alleles
present.
O.T.
Bonnett. 1953. Developmental morphology of the vegetative
and floral shoots of maize. University of Illinois
Agricultural Experiment Station Bulletin 568: 1-47.
Edward
H. Coe, and Myron G. Neuffer. 1977. The genetics of corn.
In “Corn and Corn Improvement” (G.F. Sprague,
ed)., 2nd ed. Pages 111-223. American Society of Agronomy,
Madison, Wisconsin. volume
at American Society of Agronomy
Edward
H. Coe, and Myron G. Neuffer. 1978. Embryo cells and their
destinies in the corn plant. In “The Clonal Basis
of Development" (S. Subtelny and I. M. Sussex, eds)
113-129. Academic Press. New York.
B.C.
Sharman. 1942. Developmental anatomy of the shoot of Zea
mays L. Annals of Botany 6: 245-282. (not
available online)
submitted
by: Marshall
Sundberg
