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Faculties & Departments
Department of Biology
Plastid Factory
Plastid Transformation in Crop Plants
This project is an EU funded consortium supported by the fifth framework
programme. The consortium consists of ten member institutes from all over the
EU. The Consortium believes that the chloroplast genome has great potential
for the safe efficient integration and expression of foreign genes, which could
turn the plastid into a ‘factory’ for the production large amounts of recombinant
protein. The purpose of the project is to address some key limitations to the
technology and to demonstrate some of the p redicted benefits for human and
animal health and for the environment.
This project aims to refine and expand the technology of higher plant plastid
transformation making it more accessible and applicable to a wider range of
European crops. This will involve improving the vector and DNA delivery
for plastid transformation for these crops. And to improve transformation and
selection systems to ensure heterologous antibiotic resistance genes are excluded
and regulation of transgene activity can be controlled.
Verifiable Achievements
1. Exclude antibiotic resistance
2. Expand the range of crop species suitable for plastid transformation
3. Demonstrate the use of plastid expression systems to produce antigens
for oral vaccines
4. Develop the potential of plastid transformation for phytoremediation
of heavy metal pollutants
5. Produce transplastomic crop plants with reduced need for
agrochemical application
6. Modify fatty acid composition by transformation of plants with
desaturase genes
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 develop
from the proplastid and each have a different function. The most common plastid
found in the plant cell is the chloroplast. There can be up to several hundred
chloroplasts in a cell.
CHLOROPLASTS TRAP 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 functions
are dictated by genes in the nucleus.The chloroplast itself contains a circular
molecule of DNA that also encodes genes for photosynthesis and other chloroplast
activities.
POLLEN DOES NOT CARRY CHLOROPLAST DNA
One striking feature of plastids is that its genome (the circle of DNA) is maternally
inherited in most plants. This means that the pollen grains (the male reproductive
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) of plant
species. One of the main concerns of those opposed to GM technology is the
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 pollen dispersion.
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: phil.dix@nuim.ie