PLANT PHYSIOLOGY , Vol 114, Issue 3 817-825, Copyright © 1997 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Experimental Analysis of Tassel Development in the Maize Mutant Tassel Seed 6
E. E. Irish
Department of Biological Sciences, University of Iowa, Iowa City, Iowa 52242-1298
The maize (Zea mays L.) mutation Tassel seed 6 (Ts6) disrupts both sex
determination in the tassel and the pattern of branching in inflorescences.
This results in the formation of supernumerary florets in tassels and ears
and in the development of pistils in tassel florets where they are normally
aborted. A developmental analysis indicated that extra florets in Ts6
inflorescences are most likely the result of delayed determinacy in
spikelet meristems, which then initiate additional floret meristems rather
than initiating floral organs as in wild type. I have used culturing
experiments to assay whether delayed determinacy of Ts6 mutant tassels is
reflected in an altered timing of specific determination events. Length of
the tassel was used as a developmental marker. These experiments showed
that although Ts6 tassels elongate much more slowly than wild type, both
mutant and wild-type tassels gained the ability to form flowers with organs
of normal morphology in culture at the same time. In situ hybridization
patterns of expression of the maize gene Kn, which is normally expressed in
shoot meristems and not in determinate lateral organs, confirmed that
additional meristems, rather than lateral organs, are initiated by spikelet
meristems in Ts6 tassels.
