PLANT PHYSIOLOGY , Vol 109, Issue 4 1285-1293, Copyright © 1995 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Sucrose Synthase Localization during Initiation of Seed Development and Trichome Differentiation in Cotton Ovules
K. D. Nolte, D. L. Hendrix, J. W. Radin and K. E. Koch
Horticultural Sciences Department, 1151 Fifield Hall, University of Florida, Gainesville, Florida 32611 (K.D.N., K.E.K.)
Sucrose synthase in cotton (Gossypium hirsutum L.) ovules was
immunolocalized to clarify the relationship between this enzyme and (a)
sucrose import/utilization during initiation of seed development, (b)
trichome differentiation, and (c) cell-wall biosynthesis in these rapidly
elongating "fibers." Analyses focused on the period immediately before and
after trichome initiation (at pollination). Internal tissues most heavily
immunolabeled were the developing nucellus, adjacent integument (inner
surface), and the vascular region. Little sucrose synthase was associated
with the outermost epidermis on the day preceding pollination. However, 1 d
later, immunolabel appeared specifically in those epidermal cells at the
earliest visible phase of trichome differentiation. The day following
pollination, these cells had elongated 3- to 5-fold and showed a further
enhancement of sucrose synthase immunolabel. Levels of sucrose synthase
mRNA also increased during this period, regardless of whether pollination
per se had occurred. Timing of onset for the cell-specific localization of
sucrose synthase in young seeds and trichome initials indicates a close
association between this enzyme and sucrose import at a cellular level, as
well as a potentially integral role in cell-wall biosynthesis.
