Chemistry Reference
In-Depth Information
12.1 INtrODUCtION
Geneticallymodiiedorganisms(GMOs)aredeinedasorganismsinwhichthegeneticmate-
rial[deoxyribonucleicacid(DNA)]hasbeenalteredinawaythatdoesnotoccurnaturally.Thisis
accomplished through the “recombinant DNA” or “genetic engineering” technology, sometimes
alsocalled“modernbiotechnology”or“genetechnology.”Itallowsselectedindividualgenestobe
transferredfromoneorganismintoanother,alsobetweennonrelatedspecies.Therefore,GMOsare
understoodtobeplants,microorganisms,oranimalsintowhichforeignDNAcodingoneormore
new genes has been integrated. However, so far, the term usually refers to genetically modiied
(GM)plants,whicharethenusedtogrowGMfoodcrops.Foundationlines/hybridsaretheconven-
tionalorunmodiiedparentalorisogenicline/hybridsusedintransformationevents,andtheresult-
ingGMOline/hybridsarereferredtoasthetransgenicline/hybrids.BoththeproductsofGMOs
andtheGMOsthemselvesarepotentiallyavailableforhumanand/oranimalnutrition(WHO2010).
FeedadditivesproducedfromGMmicroorganismsarealreadyofconsiderableimportancein
animal nutrition. They are added to feedstuffs not merely to provide domesticated animals with
essentialnutrientstomeettheirneeds(e.g.,aminoacidsandvitamins)andarethereforeofprimary
importanceforanimalhealth,performance,andtheeffectiveconversionoffeedconstituentsinto
foodofanimalorigin,butproductsofGMOarealsousedinanimalnutritionasnonessentialfeed
additives(e.g.,enzymes;Flachowskyetal.2005).
AworkingdistinctionisoftenmadebetweentheirstandsecondgenerationsofGMplants.This
distinction is purely pragmatic or historical and does not relect any particular scientiic principle
ortechnologicaldevelopment.Theirstgenerationisgenerallyconsideredtobethosecropscarry-
ingsimpleinputtraitssuchasincreasedresistancetopestsortoleranceofherbicides.Theproteins
produced,whichconferthesebeneits,occurinverylowconcentrationsinthemodiiedcropsand
thereforedonotsigniicantlychangeeitherthecompositionorfeedvaluecomparedtothefoundation
lines(isogeniclines).Incontrast,thesecondgenerationofGMplants,exempliiedbytheGolden
Rice(Steinetal.2006;Tangetal.2009),includescropsinwhichthenutrientcompositionoravail-
abilityhasbeendeliberatelychangedbygeneticengineering(Harlander2002;ILSI2004;Varzakas
etal.2007).Consequently,effectsonthenutritionalvalueofthefood/feedaretobeexpected.
First-generationGMcropadoptionhasexperiencedanunprecedentedrateofgrowthoverthe
past10years.Worldwide,in2008,therewere125millionhaoflandunderGMcrops,withnearly
25countriesadoptingthisnewtechnology(James2008).Theearlyadopters,namely,thetopeight
countries,growingmorethan1millionhaoflandaretheUnitedStates,Argentina,Brazil,India,
Canada,China,Paraguay,andSouthAfrica.Together,theyrepresent98%ofthe125millionhaof
landunderGMOs,outofwhich57%islocatedinNorthAmerica,32%inLatinAmerica,6%in
India,and3%and1.5%inChinaandSouthAfrica,respectively.GMmaizehasbeenthemajorcrop
adoptedbymostofthecountries(ScandizzoandSavastano2010).
The rapid global spread of GM crops has been accompanied by an intense public debate.
Supportersseegreatpotentialinthetechnologytoraiseagriculturalproductivityandreducesea-
sonalvariationsinfoodsupplyduetobioticandabioticstresses.Againstthebackgroundofincreas-
ingdemandforagriculturalproducts,naturalresourcescarcities,andadditionalchallengesposed
byclimatechange,productivityincreasesareanecessarypreconditionforachievinglong-termfood
security.Second-generationGMcrops,suchascropswithhighermicronutrientcontents,couldalso
help reduce speciic nutritional deiciencies among the poor. Furthermore, GM crops could con-
tributetoruralincomeincreases,whichisparticularlyrelevantforpovertyreductionindeveloping
countries.Inarecentanalysisoftheeffectsofinsect-resistantBtcotton,whichhasbeenadopted
bymillionsofsmall-scalefarmers,inIndia,China,andSouthAfrica,farmersindevelopingcoun-
triesseemtobeneitfrominsecticidesavings,highereffectiveyields,andsizeableincomegains.
Insights from India, in particular, suggest that Bt cotton is employment generating and poverty
reducing.Asanexampleofasecond-generationtechnology,thelikelyimpactsofβ-carotene-rich
Search WWH ::
Custom Search