Biology Reference
In-Depth Information
Figure 9.
Plastid differentiation pathways during nectary development. In
Gymnadenia
conopsea
, proplastids do not differentiate and are probably not so much involved in nectar
production. Amyloplasts present a wide range of differentiation. Before nectar secretion they
may become amylochromoplasts, after nectar secretion and starch hydrolysis they may remain
empty amyloplasts or differentiate into chloroplasts or chromoplasts.
*Empty amyloplasts can be involved in a temporary storage of reabsorbed carbohydrates if
nectar was not totally consumed by flower visitors.
peak accumulation in mature buds, but there is apparently no hydrolysis
at the time of nectar secretion, probably because of the very small amount of
nectar secreted (Fahn & Shimony, 2001).
The amyloplast membrane remains integral during starch hydrolysis in
Passiflora
sp. and
Cucurbita pepo
(Durkee et al., 1981; Nepi et al., 1996).
Plastid degeneration generally only occurs after complete starch hydrolysis
and/or nectar resorption. The degeneration of the nectary with empty
