Transgenic Ornamental Crops - Transgenic Horticultural Crops: Challenges and Opportunities - page 67

TABLE 3.3
Publications Documenting Extended Flower Life through Genetic
Engineering Ethylene Biosynthesis or Signaling

Genetic
Modiication

Plant Effect References

Petunia .x. hybrida 35S:: Atetr1-1 [87]

Flowers.lasted.∼4×.longer.than.
controls

35S::sense. PhEIN2 [88]

Flowers.lasted.∼4×.longer.than.
controls

RNAi.PhEIN2 [88]

Flowers.lasted.∼6×.longer.than.
controls

Dianthus caryophyllus Antisense.ACO ∼1.7×.longer.vase.life [77]

Sense.ACO ∼2×.longer.vase.life [78]

Antisense.and.sense.
suppression.of.ACS

∼2×.longer.vase.life [79]

PhFbp1:: Atetr1-1 [89]

∼2.7×.longer.vase.life

35S:: Atetr1-1 [89]

∼2-3×.longer.vase.life

Etr1:: etr1-1 [89]

∼2-2.4×.longer.vase.life

DcCmb2:: Atetr1-1 [80]

∼2×.longer.vase.life

Torenia fournieri Antisense.and.sense.

suppression.of.ACO

Sense.lowers.lasted.0-3.5× longer.
than.controls

[81]

Nemesia strumosa 35S:: Cmetr1 Flowers.lasted.1-3.days.longer.

than.controls

[90]

Campanula carpatica Phfbp1:: Atetr1-1 Variable..Lines.ranging.between.

0-6×.longer.than.control.lowers

[92]

Kalanchoe blossfeldiana Phfpb1:: Atetr1-1 Variable..10×.longer.lower.

retention.for.40%-50%.of.
transgenic.lowers.in.two.lines

[93]

become. widely. used. for. blocking. ethylene. effects. in. the. ornamental. industry. for.
several.decades. 67,71-73 .Unfortunately,.STS.is.a.heavy.metal.pollutant,.and.in.recent.
years. commercial. use. has. become. more. restricted. because. of. environmental. con-
cerns..1-Methylcyclopropene.(1-MCP).is.a.more.recently.developed.chemical.found.
to.block.ethylene.perception 74 .and.has.been.commercialized.and.is.effective.in.delay-
ing.lower.senescence.in.many.ornamentals.(reviewed.by.Sisler.and.Serek 75 ).

Altering Ethylene Responses Genetically by Inhibiting Ethylene Biosynthesis
The.biosynthetic.pathway.of.ethylene.has.been.elucidated 76 .and.ethylene.biosynthetic.
genes.have.been.altered.in.transgenic.ornamental.plants.to.reduce.the.effects.of.eth-
ylene..Ethylene.biosynthesis.is.a.two-step.process.beginning.with.the.conversion.of.
S -adenosylmethionine.(SAM).to.1-aminocyclopropane-1-carboxylic.acid.(ACC).by.
the.enzyme.ACC.synthase.(ACS)..ACC.is.then.converted.to.ethylene.by.ACC.oxi-
dase.(ACO)..Reducing.expression.of.either.of.these.enzymes.through.RNAi.or.cosup-
pression.technology.decreases.ethylene.production.and.extends.vase.life..Carnation.
plants.with.silenced. ACS .or. ACO .expression.produce.less.ethylene.from.lowers.and.