Insect resistant and herbicide tolerant cotton with stacked events
derived by crossing MON-15985-7 and MON-Ø1445-2.
Insect-resistance was derived from parent 15985 (tradename Bollgard
II®) which contained the cry1Ac and cry2Ab genes originally
isolated from Bacillus thuringiensis subsp. kurstaki. As a result,
event 15985 expresses both the Cry1Ac and Cry2Ab insecticidal
proteins. This protects cotton from feeding by a range of
Lepidopteran species including tobacco budworm (Heliothis
virescens), pink bollworm (Pectinophora gossypiella), cotton
bollworm (Helicoverpa zea), cabbage looper (Trichoplusia ni),
saltmarsh caterpillar (Estigmene acrea), cotton leaf perforator
(Bucculatrix thurbeiella), soybean looper (Pseudoplusia includens),
beet armyworm (Spodoptera exigua), fall armyworm (Spodoptera
frugiperda), yellowstriped armyworm (Spodoptera ornithogolli) and
European corn borer (Ostrinia nubilalis).
As with other B. thuringiensis-derived delta-endotoxins, the Cry1Ac
and Cry2Ab proteins exert their insecticidal activity by binding to
specific receptors located on the brush border midgut epithelium of
susceptible insect species. Following binding, cation-specific
pores are formed that disrupt midgut ionic equilibrium leading to
gut paralysis and eventual death due to bacterial sepsis. Cry1Ac
and Cry2Ab are highly selective and are only active against
Lepidopteran insects. These proteins do, however, interact with
different receptor sites in the target insects and it is expected
that "stacking" these traits will result in increased protection
against insect attack and a delay in the development of resistant
insect populations.
Herbicide tolerance was derived from parental line 1445 which was
transformed to express resistance to glyphosate, the active
ingredient in the herbicide Roundup®, allowing for its use as a
weed control option. In order to obtain field tolerance to
glyphosate herbicide, a bacterial gene encoding a
glyphosate-tolerant form of the enzyme
5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) was introduced
into the cotton genome.
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