Genetically engineered tomato

Jason Pfafman ez019165 at rocky.ucdavis.edu
Mon Feb 6 15:57:47 EST 1995


Brad Franzella (wizz at ecst.csuchico.edu) wrote:

: I would like to ask a a quesion for a friend who does not have USEnet 
: access..  she is doing a paper on ethics of science...  she chose genetic 
: engineering of the tomato...  and this seemed to be the closest group to 
: that topic...

: Send me any information you can muster on this topic or referr me to any 
: Telnet or FTP site with info (or WWW)...

: Please send via E-mail... thanks in advance...

: This is your chance to show some liberal professor who screams rape of the 
: natural world that science is both ethical and safe... and that we KNOW 
: what we are doing (Well in most cases)... and that this tomato won't end 
: the world as we know it from some new disease created with (or as a 
: result of) the tomato...  (heck we get half our drugs from altering the 
: DNA of bacteria.. I've personally made a colony of E-coli resistant to 
: amphacilin... this is the same type of thing with the tomato, right?)

: As far as I remember it was engineered to have a longer shelf life... and 
: become resistant to pests.. something to do with the secretion of a 
: substance within the tomato?

: Thanks

: -- 
: | Clear skies and God speed,  \    Amateur astronomer on the loose..........|
: | Brad Franzella              \   Wannabe physicist acting up...............| 
: | wizz at ecst.csuchico.edu      \  Babylon 5 nut on the prowl.................|
: | California State University \ Computer geek on-line..(damn it, not again!)|

	In the case of tomatoes, Calgene here in Davis recently had their 
Flavr-Saver tomato approved by the FDA.  As I had it explained to me by a 
genetics professor, I would not worry anytime soon about rampant diseases 
springing forth from these tomatoes.
	The way I understand the process, most of the research spent by 
Calgene was to identify the actual gene in the tomatoes responsible for 
ripening on the vine.  Once this gene was precisely located, they excised 
the gene to replicate it, sequenced it in reverse, and inserted the 
reversed gene back into the genome.  The techniques used can be found in 
any introductory genetics textbook.
	The effect of reversing this gene for ripening is to delay the 
process.  The desire of Calgene in tackling this project was to improve 
the flavor of mass produced tomatoes.  Consumer fickleness demands 
unblemished tomatoes in the marketplace.  To accommodate the consumers, 
the growers pick the tomatoes while the plant is still resistant to 
bruising, which happen to be while the fruit is green.  This allows them 
to pick the tomatoes, dump them in the trucks, ship them to market, and 
put them on the shelf.  The sacrifice to getting an unblemished tomato is 
that the actual growing time on the vine is reduced, preventing the 
fruits from achieving their full potential growth.
	Rather than build a tomato from the ground up (a very daunting 
task), the gene for ripening can be reversed.  An example of this would 
to think about a book you are reading.  Imagine yourself reading along, 
when suddenly, you come across a page (which contains essential 
information to a test you have to take) that has been written backwards.  
You can eventually read the entire page, top to bottom, but you have 
expended a lot of time doing so.  For the tomato, the time spent in 
trying to ripen is the period in which it is shipped to market.  Growers 
can let the fruit grow longer, knowing that ripening on the vine is 
delayed.  The end product is a more fully developed tomato, which tastes 
better, not because it was engineered to taste better, but because it could 
grow longer on the vine longer.
	The amount of genetic engineering that went on is very little.  
I think that opponents of genetic engineering need to look a little 
closer at what goes on in such products before accusing genetic engineers 
of creating a new potential for disease.  Such genetic work amounts to 
little more than manipulating the genome, which plant breeders have been 
doing in one form or another for hundreds of years.  It has only been in 
the last few decades that we have come to understand our macroscopic 
manipulations on the molecular scale.  If people reject out of hand ag 
products that have undergone lab work, perhaps they should examine more 
closely everything that they eat.  They might not be so happy at what 
they find.  In the end, the best way to protect yourself is to educate 
yourself.  Once you understand, do what you like.

				Hope this helps,

				Jason Pfafman
				Botany
				University of California, Davis
				



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