1996; Lariguet and Fankhauser, 2004), where phytochrome is found to promote the conversion of amyloplasts
to other forms of plastids in the endodermis, causing cessation of hypocotyl gravitropism (Kim et al.
There is an exception concerning amyloplast
formation during the bicellular stage of some grasses, such as Sorghum bicolor, in which the plastids next to the tapetum accumulate starch before those that are far from the tapetum do (Christensen & Homer, 1974).
The vegetative cell cytoplasm is very dense, filled with numerous small vesicles, mitochondria, lipidic globules, amyloplasts
and ERr with extended cisternae.
Arena starch grains have numerous small and distinctive pressure facets due to the grains packing together very tightly in the amyloplasts
during their formation (Figure 5).
If polarized light microscopy is included, it can be used as a tool to identify plant material on the basis of the Maltese cross evident in amyloplasts
when viewed with crossed polars and the birefringence exhibited by cellulosic fibers (for complete instructions for a lab on polarized light microscopy, see McMahon, 2004).
Proteomic characterization of wheat amyloplasts
using identification of proteins by tandem mass spectrometry.
While gravity causes the sedimentation of starch-laden amyloplasts
during perception, background vibration may be partially counteracting this stimulus.
In addition to working as photoassimilate repositories, soybean cotyledons become green and expand, suggesting that their amyloplasts
are transformed into chloroplasts.