Transgenic Fruit Crops in Europe - Transgenic Horticultural Crops: Challenges and Opportunities - page 141

ihp- CHS-RNAi Control

FIGURE 5.7 ( See color insert. ).Transient.silencing.of.the.chalcone.synthase.( CHS ).gene.in.
strawberry.fruits.(left).after.agroiniltration.using.the. ihp-CHS-RNAi .gene.construct.(accord-
ing. to. Hoffmann. et.al. 44 ).. (The. igure. was. kindly.provided. by. Wilfried. Schwab,. Technical.
University.Munich,.Biomolecular.Food.Technology,.Germany.)

health. or. to. the. environment,”. there. remains. a. reluctance. to. use. this. impor-
tant. tool. for. GM. plant. selection.. Therefore,. it. is. considered. essential. by. many.
research.groups.to.establish.methods.which.allow.the.production.of.marker-free.
plants..Clean.vector.technologies.are.the.most.promising.strategy.because.other.
methods,. which. are. based. on. sexual. outcrossing. of. the. marker. gene,. are. not.
usable. for. fruit. crops.. Self-incompatibility. and. a. high. degree. of. heterozygoz-
ity. make. such. methods. often. unsuitable.. The. irst. successes. in. the. establish-
ment.of.clean.vector.technologies.have.recently.been.reported.for.apple, 46 .sweet.
oranges, 47 . strawberry, 48 . and. apricot. 49,50 . However,. the. development. of. highly.
effective. strategies. for. the. production. of. marker-free. plants. is. still. one. of. the.
most.important.goals.in.many.countries..For.apple,.there.is.a.large.program.in.
progress.at.the.moment..Scientists.of.several.countries.have.joined.into.Working.
Group.4.“Biotechnological. Approaches.for.Pome.Fruit.Trees”.of.the.European.
COST-Action. 864. “PomeFruitHealth.”. They. evaluate. various. vector. systems.
(an. example. is. shown. in. Figure. 5.8). to. ind. the. most. usable. system. for. apple.
transformation.
Other.technologies.such.as.transformation.without.the.use.of.marker.genes.have.
also.been.tested.on.apple. 12,13 .While.the.results.are.promising,.no.molecular.evidence.
exists.to.date.conirming.these.results.
All.of.these.technologies.offer.the.possibility.to.transfer.a.gene.of.interest.from.
one. to. another. genotype.from. the. same. or. a. crossable. species. without.DNA. from.
noncrossable.organisms..In.Europe.the.irst.commercial.GM.plant.will.likely.contain.