Kd. Nolte et al., SUCROSE SYNTHASE LOCALIZATION DURING INITIATION OF SEED DEVELOPMENT AND TRICHOME DIFFERENTIATION IN COTTON OVULES, Plant physiology, 109(4), 1995, pp. 1285-1293
Sucrose synthase in cotton (Gossypium hirsutum L.) ovules was immunolo
calized to clarify the relationship between this enzyme and (a) sucros
e import/utilization during initiation of seed development, (b) tricho
me differentiation, and (c) cell-wall biosynthesis in these rapidly el
ongating ''fibers.'' Analyses focused on the period immediately before
and after trichome initiation (at pollination). Internal tissues most
heavily immunolabeled were the developing nucellus, adjacent integume
nt (inner surface), and the vascular region. Little sucrose synthase w
as associated with the outermost epidermis on the day preceding pollin
ation. However, 1 d later, immunolabel appeared specifically in those
epidermal cells at the earliest visible phase of trichome differentiat
ion. 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, re
gardless of whether pollination per se had occurred. Timing of onset f
or the cell-specific localization of sucrose synthase in young seeds a
nd trichome initials indicates a close association between this enzyme
and sucrose import at a cellular level, as well as a potentially inte
gral role in cell-wall biosynthesis.