Weed Test 3 Flashcards
3 biochemical mechanisms for natural herbicide selectivity
detoxification of herbicide by crop plant
insensitivity of the target enzyme
lack of uptake and trans location of herbicide
Round up ready technology
glyphosate- generic
binds to and blocks EPSPS in shikimate pathway interrupting plant growth and metabolism
Shikimate pathway
found in chloroplasts or plastids of plants
responsible for production of phenylalanine, tyrosine, and tryptophan
required for plant functions such as UV protection, electron transport, plant defense, and wound response
glyphosate resistant crops
insensitive EPSPS strain CP4 having high glyphosate tolerance
most commerical seed contains bacteria EPSPS enzyme that occurs naturally
substrate and glyphosate binding site identical to that of sensitive EPSPS found in most plants why it works so well
has high affinity for PEP with high tolerance for glyphosate and bypasses endogenous EPSPS system that allows shikimate pathway to function as in absense of glyphosate
Liberty Link technology
glufosinate- generic
broad spectrum contact herbicide
inhibits glutamine synthetase
ammonium level increases rapidly literally burning up the plant
BAR and PAT homologous enzymes inactivate glufosinate
isolated genes from soil microorganisms
can give resistance to whole plants or as a selectable marker
glutamine synthesase
enzyme that catalyzes conversion of glutamate plus ammonium to glutamine through nitrogen metabolism
Clearfield technology
tolerance to imidazolinone herbicides developed from a single rice plant that survived mutation
resisitance to ALS herbicides occurs by point mutations in ALS genes
ALS herbicides inhibits production of the enzyme
ALS enzyme becomes insensitive to some or all ALS herbicides
round up ready 2 xtend
soybeans
genuity rr 2 yield trait (glyphosate) stacked with trait with tolerance to dicamba
bollgard II xtendflex
cotton
biotech-stacked trait herbicide tolerance to dicamba, glyphosate, glufosinate
Dicamba
benzoic acid herbicide
mimics plant hormone indole acetic acid (IAA) causing nucleic acid metabolism and cell wall plasticity
Enlist-Duo
combines 2,4-D choline and glyphosate
2,4-D tolerance
synthetic auxin that mimics plant hormone IAA causing nucleic acid metabolism and cell wall plasticity
absorbed through leaves and translocated to meristems of plant
herbicide resistance
inherited ability of a plant to survive and reproduce following exposure to a dose of herbicide normally lethal to wild type
what used to kill it doesn’t work now
tolerance
inherent ability of a plant to survive and reproduce with a herbicide treatment at a normal use rate
herbicide never did kill that weed species
cross-resistance
resistance to 2 or more herbicides resulting from a single resistance mechanism
multiple-resistance
resistance to several herbicides resulting from more than one resistance mechanism
what causes resistance
selection pressure
mutations
selection pressure caused by
initial frequency of the resistant individuals
weed seed residue in soil seed bank
hypersensitivity of weeds to a particular herbicide
lack of rotation of herbicide
herbicide with long residue period
herbicide with highly specific mode of action
