Agriculture Reference
In-Depth Information
c
ulture
S
yStemS
Somatic.embryogenesis.is.well.documented.for.grapevine.
7-9
.Most.successful.exam-
ples. of. transformation. have. utilized. such. embryogenic. culture. systems. because.
embryogenic.cells.are.capable.of.being.genetically.transformed.and.can.be.induced.
to.regenerate.into.plants.
1,2
.Thus,.once.a.cell.is.stably.transformed,.a.transgenic.plant.
can.be.produced..A.drawback.to.use.of.embryogenic.cultures.is.that.they.have.been.
dificult. to. obtain. for. many. varieties.. However,. this. obstacle. is. slowly.being. over-
come.through.experimentation.and.reinement.of.culture.techniques.
7,10
Cells. of. the. shoot. apical. meristem. obtained. through. in. vitro. micropropagation.
were. considered. as. a. potential. alternative. to. embryogenic. cells. for. transformation..
The. ease. of. producing. and. maintaining. in. vitro. micropropagation. cultures. from. a.
large.number.of.cultivars
11,12
.makes.development.of.a.shoot.tip-based.transformation.
system.attractive..However,.use.of.shoot.apical.meristems.for.transformation.has.met.
with.limited.success.in.grapevine.
13
.Problems.that.inhibit.their.use.likely.include.a.rel-
atively.low.number.of.totipotent.cells.in.the.shoot.apex.to.be.transformed,.when.com-
pared.to.embryogenic.cultures,.and.the.propensity.for.chimeric.plants.to.be.recovered.
m
ethodS
of
G
ene
I
nSertIon
As.reviewed.by.Gray.et.al.,
1
.the.two.commonly.used.methods.of.gene.insertion,.biolistic-
mediated.and.
Agrobacterium
-mediated.transformation,.have.been.successfully.utilized.
for.grape..Biolistic.bombardment.resulted.in.intense.transient.beta-glucuronidase.(GUS).
expression.in.somatic.embryos.of.
V. vinifera
.'Thompson.Seedless'
14
.and.has.been.used.
to.produce.transgenic.plants.from.embryogenic.suspension.cultures.of.'Chardonnay',.
'Merlot',.and.'Chancellor'.
15,16
.However,.
Agrobacterium
-mediated. transformation.has.
been.utilized.more.frequently.and.currently.appears.to.be.the.transformation.system.of.
choice.for.grape.(see.Dhekney.et.al.
3-5
.and.Li.et.al.
6
.for.recent.examples).
m
arker
G
eneS
Development. of. transformation. protocols.for. grape. has. been. greatly.facilitated. by.
reinement.of.genetic.vectors.that.eficiently.express.various.reporter.genes..Visible.
reporter. genes. inserted. in. grape. include. GUS,
14
. green. luorescent. protein. (GFP),
17
.
and. luciferase.
18
. The. selectable. marker. genes,. phosphinothricin. acetyl. transferase.
(PAT,. or. BAR. for. Bialaphos. resistance). gene,
19
. hygromycin. B. phosphotransferase.
(HPH). gene,
19
. and. neomycin. phosphotransferase. (NPTII). gene,
17
. have. been. used,.
with.the.latter.being.most.common.
f
unctIonal
G
eneS
Establishment. of. reproducible. transformation. protocols. has. enabled. the. insertion. of.
transgenes.for.quality.trait.improvement.including.fungal,.bacterial,.and.viral.resistance.
in. elite. grapevine. varieties.. Genes. encoding. pathogenesis-related. (PR). proteins. have.
been.widely.tested.to.enhance.grapevine.fungal.resistance..'Thompson.Seedless'.grape-
vines.transformed.with.an.endogenous.thaumatin.like.protein.(
VVTL-1
).gene.exhibited.
signiicant.resistance.to.powdery.mildew.(
Uncinula necator
).and.black.rot.(
Guignardia
bidwellii
).in.greenhouse.and.ield.tests.
20,21
.Berries.of.'Shiraz'.grapevines.transformed.
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