July 21, 2003

from Crop Biotech Update July 13, 2003

Agricultural researchers in the US are currently exploring the use of genetically engineered plants for
economical and large-scale production of recombinant proteins for industrial, research and clinical
applications.

Different strategies were developed by plant biotech researchers for protein expression in plant
species such as corn, rice, wheat, tobacco, alfalfa, tomato, banana, potato, oilseed rape and
soybean.

The researchers used the soil microbe Agrobacterium tumefaciens or direct transfer procedure such
as electroporation, microinjection or biolistic bombardment, transgenes to introduce and be expressed
in plants. Proteins can also be expressed in the entire plant or can be targeted to specific plant
organs.

The scientists are exploring various options to address the concern of environmentalist groups on the
possible spread of the transgenes and their encoded proteins to the environment. These include
asexual reproduction, male sterility, plant host genomes incompatible with nearby related species,
chloroplast genetic engineering, and methods for doing recombinant technology without selectable
markers.

Since regulatory agencies such as the US Food and Drug Administration, and US Department of
Agriculture have established a growing body of safely guidelines, several companies are beginning to
move forward in developing, testing, and utilizing plants for protein expression.

Lee Quarles, of Monsanto Protein Technologies, says that manufacturing costs could be decreased
from four to five folds via plant-based expressions as compared to traditional cell culture techniques.

The full paper is published at The Scientist, Vol. 17, Issue 14, No. 45.