C. Gilly et al., ULTRASTRUCTURE AND RADIOLABELING OF LEAF CUTICLES FROM IVY (HEDERA-HELIX L) PLANTS IN-VITRO AND DURING EX-VITRO ACCLIMATIZATION, Annals of botany, 80(2), 1997, pp. 139-145
Cuticle ultrastructure and radiolabelling of isolated cuticles after i
ncorporation of [C-14] acetate in foliar discs were investigated with
ivy plants grown in vitro then ex vitro. Results show an increase in t
hickness, mass and wax content, between young and expanded leaves, for
both in vitro and ex vitro cuticles. The cuticle of in vitro unexpand
ed leaves was very thin and only constituted a lamellate zone. The ult
rastructure of in vitro young and expanded leaf cuticles showed charac
teristics similar to in situ cuticles. The thickness of the lamellate
zone remained fairly constant and represented 33% of the cuticle thick
ness in young leaves, but only 11.4% in expanded leaves. The number of
lamellar units decreased from 14 to nine between these two growth sta
ges. The main difference between young leaves developed in vitro or ex
vitro was a thinner lamellate zone for ex vitro cuticles. However. th
ese latter cuticles had an intermediary zone between the lamellate and
reticulate zones. The cuticle thickness of expanded leaves was greate
r for in vitro cuticles suggesting a temporary decrease in cuticle bio
synthesis after transfer of the plant from in vitro to ex vitro. Resul
ts from cuticle radiolabelling show higher radioactivity incorporation
in cuticles isolated from leaves developed ex vitro compared to in vi
tro. This radiolabelling was particularly marked for ex vitro young le
af cuticles and depended on the duration of the ex vitro growth period
revealing a progressive activation of cuticle biosynthesis in respons
e to new environmental conditions (C) 1997 Annals of Botany Company.