Genetic Engineering of Grapevine and Progress toward Commercial Deployment - Transgenic Horticultural Crops: Challenges and Opportunities - page 318

INTRODUCTION
Grapevine.is.the.world's.most.valuable.fruit.crop.due.to.its.multipurpose.uses.for.
fresh. fruit,. wine,. and. other. processed. products.. While. many. species. of. grape-
vine. exist,. as. described. below,. the. predominant. species. used. in. commerce. is.
Vitis vinifera .L..This. species. originated.in.the. Middle.East. and.is.adapted. to.a.
Mediterranean. environment.. It. has. diversiied. into. hundreds. of. varieties. since.
antiquity.. Major. production. areas. in. the. world. tend. to. be. those. possessing.
Mediterranean. climatic. conditions.. Despite. widespread. consumption. of. grape.
products,.attempts.to.grow. V. vinifera .in.climates.that.are.too.cold.or,.especially,.
too. humid. have. met. with. failure.. It. would. be. advantageous. to. have. V. vinifera .
varieties.with.more.resistance.to.diseases.caused.by.bacteria,.fungi,.and.viruses.
in. order. to. foster. more. widespread. production. and. thus. address. local. market.
needs.and.opportunities.
While. V. vinifera .has.been.hybridized.with.native.species.to.create.land.races.for.
suboptimal.regions,.this.approach.has.met.with.limited.success.due.to.the.consum-
er's.strict.preference.for.the.exact.phenotypic.characteristics.of.well-known.varieties..
This.is.because.grapevine.is.genetically.self-incompatible,.making.it.impossible.to.
create.inbred.lines.needed.to.introgress.desirable.traits.from.resistant.native.species.
into.existing.elite.varieties..Although.clonal.selection.of.randomly.occurring.muta-
tions. has. been. successful. in. creating. new. varieties,. it. is. a. haphazard. process. and.
cannot.produce.grapevines.with.desirable.resistance.traits. 1
Genetic.transformation.offers.an.alternate.method.for.adding.speciic.traits.into.
otherwise.desirable.varieties..Presumably,.varieties.altered.only.by.the.addition.of.
genes. for. resistance. (or. other. traits). would. retain. their. elite. characteristics. 2 . Only.
recently.has.genetic.transformation.technology.matured.for.grapevine,.such.that.it.is.
now.commonplace.in.certain.laboratories.to.insert.genes.and.produce.transgenic.ver-
sions.of.popular.varieties. 3-6 .It.now.remains.to.study.grapevines.containing.various.
transgenes.for.their.performance,.which.includes.expression.of.new.desirable.traits.
as.well.as.whether.the.high.level.of.clonal.idelity.demanded.of.grape.is.maintained.
in.transgenic.vines.
This. chapter. will. review. the. progress. in. genetic. transformation. of. grapevine,.
including. discussion. of. the. most. recent. methods. and. procedures. that. have. led. to.
successful.transformation.. Status.of.ield.tests. and.issues. related.to.environmental.
release.of.transgenic.grapevines.will.be.presented.
GRAPE GENETIC TRANSFORMATION
Signiicant. progress. in. grapevine. transformation. has. been. made. 1-3,5,6 . Genetic.
transformation. has. become. relatively. routine. for. 'Chardonnay',. 'Merlot',.
'Superior. Seedless',. and. 'Thompson. Seedless'. (='Sultana',. 'Sultanina'),. among.
others..However,.several.fundamental. technologies.were.required.before.trans-
formation. of. grapevine. could. be. studied.. These. included. regenerative. cell. cul-
ture.systems,.methods.for.gene.delivery,.and.then.advances.in.molecular.genetic.
techniques.to.identify.useful.genes.and.place.them.into.functional.DNA.cassettes.
that.could.be.tested.