in Crop Plants
WHAT ARE PLASTIDS?
AND WHY IS IT USEFUL TO TRANSFORM THEM?
Plastids develop from proplastids which are small organelles found in
the plant cell.
Several kinds of plastid e.g. chloroplasts, chromoplasts and leukoplasts
from the proplastid and each have a different function. The most common
found in the plant cell is the chloroplast. There can be
up to several hundred
chloroplasts in a cell.
THE SUNS ENERGY
The main function of the chloroplast is to harness the energy
from sunlight and
use it to convert carbon dioxide and water to sugars that can
used or stored by
the plant. This process is known as photosynthesis. Most chloroplast
are dictated by genes in the nucleus.The chloroplast itself
contains a circular
molecule of DNA that also encodes genes for photosynthesis and other
POLLEN DOES NOT
CARRY CHLOROPLAST DNA
One striking feature of plastids is that its genome (the circle of DNA)
inherited in most plants. This means that the pollen grains (the
cells carry the genetic information contained in the nucleus but not
in the chloroplast.
This fact can be exploited in the context of genetic modification (GM)
species. One of the main concerns of those opposed to GM technology
containment of the modified gene within the transgenic crop.
It is argued that
there would be no control on the escape of novel genes via
If however, using this technology, the novel genes
were contained in the
chloroplast, the pollen grains would remain "unmodified"
and so pose no
threat of spread of the novel gene by pollen dispersion.
Contract no: QLK3-CT-1999-00692
Coordinator: Prof. Phil Dix, Department of Biology, NUI Maynooth,
Co. Kildare, Ireland.
Any questions? Email:firstname.lastname@example.org
Chloroplast image from: www.brigadoon.com/~schafer/biology/chloropl.html