Genetic Engineering of Grapevine and Progress toward Commercial Deployment - Transgenic Horticultural Crops: Challenges and Opportunities - page 327

used.readily.to. produce.grapevines.with.a.range.of.other.nonselectable.genes.and.
may.be.adapted.for.use.in.other.vegetatively.propagated.crops.as.well.

Rootstocks
Grafting.of.scion.to.a.rootstock.is.commonly.used.for.grapevine.in.most.production.
areas..The.possibility.of.using.a.transgenic.rootstock.that.resists.soil.stresses.and/or.
transmits. a. useful. substance. into. the. scion. is. intriguing. for. several. reasons.. For.
example,.only.the.non-transgenic.scion.would.reproduce.pollen.or.seed,.so.that.there.
would.be.no.possibility.for.transgene.low.to.occur,.and.virtually.any.scion.could.be.
grafted.onto.a.transgenic.rootstock,.thus.reducing.the.number.of.transgenic.variet-
ies.to.be.developed.and.tested..Rootstocks.that.produce.lytic.peptides.to.inhibit.the.
xylem-limited.bacterium.that.caused.Pierce's.disease.of.grapevine.are.in.ield.tests. 92 .
The.direct.vascular.connection.of.rootstock.to.scion.allows.lytic.peptide.produced.
and.accumulated.in.rootstock.xylem.to.be.transported.into.the.scion. 93

CONCLUSION
Genetic.transformation.of.grape.is.no.longer.an.obstacle.to.progress.in.development.
of.improved.transgenic.grapevines..However,.it.is.dificult.to.predict.when.a.trans-
genic.grape.product.will.become.commercially.available..While.it.is.now.possible.
to.insert.virtually.any.gene.of.interest.into.an.increasingly.wide.range.of.elite.grape.
varieties,. ield. testing. has. been. insuficient. to. prove. the. expected. eficacy. of. new.
traits;.one.problem.being.the.time.required.to.evaluate.such.a.perennial.fruit.crop..
Also,.needs.to.conduct.risk.assessment.studies.and.develop.consumer.acceptance.of.
any.transgenic.crop.have.proven.to.be.costly.and.dificult..One.alternate.approach.
to.reducing.the.concerns.associated.with.transgenic.plants.is.to.adopt.the.aforemen-
tioned.cisgenics.approach.to.crop.development.wherein.only.genes.and.other.genetic.
elements. taken. directly. from. grapevine. are. used.. Such. a. green. approach. is. more.
akin.to.“precision.breeding”.inasmuch.as.it.disrupts.the.plant.genome.even.less,.and.
is. more. predictable,. than. conventional. breeding.. Similarly,. the. implementation. of.
transgenic.rootstocks.to.combat.diseases.in.the.scion.could.have.a.similar.impact..We.
believe.that.grapevines.developed.in.this.manner.to.have.improved.disease.resistance.
and.quality.attributes.will.be.desirable.to.growers.and.be.accepted.by.consumers.

REFERENCES
. 1.. Gray,.D.J.,.Jayasankar,.S.,.and.Li,.Z.,.Vitaceae.(Grape. Vitis .spp.),.in. Biotechnology of

Fruit and Nut Crops ,.Biotechnology.in.Agriculture.Series,.No..29,.Litz,.R.E.,.ed.,.CAB.
International,.Wallingford,.U.K.,.2005,.Chap..22,.pp..672-706.

. 2.. Gray,.D.J..et.al.,.Transgenic.Grapevines,.in. Transgenic Plants ,.Khachatourians,.G.G..

et.al.,.eds.,.Marcel.Dekker,.New.York,.2002,.Chap..27,.pp..397-405.

. 3.. Dhekney,.S.A..et.al.,.Factors.inluencing.genetic.transformation.and.plant.regeneration.

of. Vitis ,. Am. J. Enol. Vitic .,.60,.285,.2009.

. 4.. Dhekney,.S..A..et.al.,. Agrobacterium -mediated.transformation.of.embryogenic.cultures.

and. regeneration. of. transgenic. plants. in. Vitis rotundifolia . Michx.. (muscadine. grape),.
Plant Cell Rep .,.77,.865,.2008.