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Genetically Modified Food Crops
Volume 10, Issue No. 1
About This Issue...
First Questions How is our food grown?
Which food plants are wild?
What do genes do?
What plants are safe to eat?
Can eating genes infect you?
Are all bacteria bad for plants?
Can carrots make you see better?
How many hours did you spend growing yourfood yesterday? You probably just walked to thefridge. But a hundred years ago you might haveworked more hours in the fields thanin school. In the developing world,thats still the case, and food isboth scarce and expensive.
Throughout history,peoples main concern wasproducing enough food.Civilization advanced as wedeveloped agriculture. For10,000 years we bred wild plantsto produce more food with lesswork. Agriculture got a boost inthe 1950s with new chemicals thatcontrol insects, weeds, and disease.At the same time, plant breedersdeveloped more productive varieties ofwheat, corn, and rice. Together, newfarm chemicals and improved crops led tomuch higher yields (amounts produced).This increase in production was known asthe Green Revolution.
The Green Revolution happened at a time whenthe worlds population was growing so fast thatexperts predicted massive famines. But the new,more productive crops came to the rescue. India
Whoever could make two ears of corn, or two blades of grassgrow upon a spot of ground where only one grew before would
deserve better of Mankind, and do more essential service
for his country, than the whole race of politiciansput together.
-The King of Brobdingnag,Gullivers Travels by Jonathan
more than tripled the wheat grown on the sameamount of land. There have been localized faminescaused by drought, war, and political corruption, butno worldwide starvation.
As we enter the 21st century, industrialized coun-tries are struggling with side-effects of the GreenRevolution. The overuse of agricultural chemicals is
polluting our land, wildlife, and water.In addition, the worlds
2 Genetically Modified Food Crops
Creating Better Plants ....................................... 4Weed Warriors ................................................. 6Monarch Butterfly Effect .................................. 8Golden Rice .................................................... 10Potato Power .................................................. 12Profile: Florence Muringi Wambugu ................ 14Something you can try: Growing Soybeans and Researching Monarchs .......................... 15
Volume 10, Issue No. 1
Published by:The Biotechnology Institute
In Partnership with:Pennsylvania Biotechnology AssociationBiotechnology Industry Organization
Originally Developed by:The Pennsylvania Biotechnology AssociationThe PBA Education CommitteeSnavely Associates, Ltd.
Writing by:The Writing Company, Cathryn M. Delude andKenneth W. Mirvis, Ed.D.
Design by:Snavely Associates, Ltd.
Illustrations by:Patrick W. Britten
Science Advisor:C. S. Prakash, Professor, Tuskeegee Universitywww.agbioworld.org
Special thanks to:Peggy Lemaux, Ph.D., University of California, BerkeleyWayne Parrott, Ph.D., University of Georgia
For more information:Biotechnology Institute1524 W. College Avenue, Suite 206State College, PA 16801800-796-5806www.BiotechInstitute.org
Copyright 2000, BI. All rights reserved.
The BiotechnologyInstitute is dedicated toenhancing theunderstanding of bioscience among lay audiences and infostering public education collaborations amongbioscience companies, universities, and non-profitorganizations.
Your World describes the application of biotechnology toproblems facing our world by bringing scientific discoveriesto life. We publish issues on different topics each fall andspring. If you would like information on subscribing forindividual, teacher, or library sets, or if you would like tosponsor distribution in your area, contact the BiotechnologyInstitute. Some of the fifteen back issues are available.
On the cover: For thousands of years, farmers havebeen crossbreeding plants to create better and healthiercrops. Today, scientists are using their understanding of DNAto develop plants with specialized traits, ranging from diseaseand pest resistance to better taste and nutrition.
The Biotechnology Institute would like to thank thePennsylvania Biotechnology Association, which originallydeveloped Your World.
Biotechnology & You
growing beyond the Green Revolutionscapacity to feed it. People are destroy-ing sensitive habitats to create morefarmland, but even so, there will not beenough land to feed the 9 billion peoplepredicted by 2050.
Worse, many of the worlds poor havenever benefited from the Green Revolutionbecause it did not solve the underlyingproblem: poverty. Many farmers cant affordthe chemicals and improved seeds. Millionsstill survive on a daily bowl of rice or potatoes.
They have no roads tostores, no fresh produce, and no vitamin pills and
their health suffers terribly. What can help them?Many scientists think a new Gene Revolu-
tion can help both hungry humanity andthe sensitive environment. The GeneRevolution uses biotechnology to createnew genetically modified or GM crops.
These crops can potentially produce morefood with fewer chemicals and higher
nutritional value than traditional crops.Scientists think they can improve even more
crops than the Green Revolution did: not onlygrains, but also the legumes, vegetables, roots,
and fruits that people need for a balanced,nutritious diet.
But some people worry that thesecrops are not safe to eat and couldthreaten the environment with unfore-seen problems. They questionwhether government agencies test theproducts enough and whethercorporate profit motives outweighsafety concerns. Some protestershave destroyed research laboratoriesand burned fields of GM crops.
This issue of Your World willhelp you unravel conflictingreports about agricultural biotech-nology. Is it safe and environmen-
tally friendly or an out-of-controlexperiment? You will learn how
plants with specific traits are created,how to weigh the pros and cons, andhow you can investigate these problems.
Your World 3
4 Genetically Modified Food Crops
1) Scientists copy acarrot gene thatconverts a pigment tobeta-carotene.
Plants live in a hostile world. Animals chew them, insects chomp them, pushy
plants surround them, and disease withers them. But plants are not
helpless. They make oils, smells, and poisons to fight back.
If you look at a leaf of a tomato plant under a microscope, youll see the leaf iscovered with tiny hairs. These hairs emit chemicals that act like flypaper to trap
little insects. How did this insect-fighting trait come about?
How do plants getdifferent traits?
2) They insert the carrotgene into a plasmid.
3) The plasmid isreintroduced into theAgrobacterium.
4) The Agrobacteriumtransfers the carrotgene to the cells oftomato leaves in apetri dish.
5) The tomato cells growand divide in a culturewith hormones thatencourage the cells tobecome new shootsand roots.
6) As the tiny new plantsgrow, the carrot geneconverts the tomatospigment into beta-carotene, creating anenhanced tomato.
Creating a Vitamin-Rich Tomato with a Carrot GeneThe bacterium Agrobacterium naturally infects plants. It carries some genes on a circular piece ofDNA called a plasmid and inserts those genes into plant cells. Scientists are now able to remove thebacteriums genes that cause plant disease and add a gene for a desirable trait.
Photos courtesyof Shelia Colby,University ofCalifornia, Berkeley.
Your World 5
Discoveries BehindGenetic EngineeringThe door to genetic engineering opened when scien-tists realized that all genes are written in the universallanguage of DNA. Learning to use plasmids (seeillustration) and special cut and paste proteins calledrestriction enzymes allowed them to edit DNA.Now, plant genomics is cataloging genes that couldgive plants beneficial traits, as well as genes we couldeliminate to make food safer. (See box on page 7.)
Natural SelectionWild tomatoes may have developed these tricky leaf hairs by
chance. To reproduce, plants pollinate each other. In doing so,they exchange genes the molecular instructions that producedifferent traits. The offspring have a different combination fromeither of their parents. Occasionally, genes undergo mutations(changes) during this mix. One such change made the leaf haircells produce the sticky insect-fighting proteins. This mutationgave that plant an edge over others, so it passed its insect-resistance on to new generations.
Selective BreedingAlong came the age of farming, and people noticed the insect-
resistant tomato. They selected it to pollinate other tomatoes,such as those with bigger fruits. To understand selective breed-ing, imagine that a gene is a book in a library. Different toma-toes have different versions of certain books. One plant mayhave a book for the insect-trapping flypaper. Another plant may
have a book that makes big fruits. If afarmer cross-pollinates these twoplants, eventually one offspringmight combine both traits. Butgenes dont mix individually;they come linked with otherbooks on their shelves. Thebig fruit book may come linkedto a sour fruit book. Gettingrid of that sour book might takegenerations of selective breed-
ing, if it could be done at all.Selective breeding has given us a
huge variety of plants. Over time, cultivatedvarieties have little similarity to the original wild
plant. For example, early Na