COMPOSITIONAL ASSESSMENT OF GENETICALLYMODIFIED(GM) PLANTS USED FOR FOOD AND FEED

Thousands of evaluations over 25 years have repeatedly proven GM crops
to be as safe as their conventional counterparts. It’s time to evaluate how
food/feed safety assessments are conducted for GM crops, and focus
data requirements to address plausible risk.
The learnings and experience over thepast 25 years now suggest improvements
in how we evaluate the compositionalsafety of GM crops.
When GM crops were first commercialized over25 years ago, crop composition studies wererecommended due to uncertainty of the potential
for transgene insertion to have a greater effecton the safety and nutrition of food and feed
compared to traditional breeding methods with ahistory of safe use.
Advances in molecular biology and genetics haverevealed that the genetic changes responsible forcompositional variation are mechanistically thesame in traditionally bred crops and GM crops, but
those in GM crops are generally less frequent andless substantial.
Empirical evidence from all studies to dateshows that development of a GM crop induces
less compositional variation than developmentof traditionally bred varieties, and that thebackground genetics of the variety and theenvironment in which it is grown have a muchlarger impact on the composition of the crop.
Compositional changes produced through theinsertion of a GM trait are predictable and no
unexpected unsafe compositional changes havemanifested in GM crops or commercial breeding
stacks of GM events.
A greater understanding of both the genetics andmechanism for achieving a GM trait increase theability to predict compositional changes in GM
crops compared to traditional breeding.
The mechanism of action for the transgene can beused to determine potential effects on metabolic
pathways and the potential resulting effects oncrop composition that could affect safety ornutrition.

Scientific advances in molecular biology
and genetics allow for a more focusedand streamlined approach to theevaluation of GM crop compositionalsafety.
Example Assessment:

1) Determine what metabolites/components
could be affected:
Trait affecting hydroxyphenylpyruvate dioxygenase (HPPD) insoybean
Plastoquinone/Tocopherol
Synthesis

Carotenoid Synthesis

Tyrosine

Glyceraldehyde-3-phosphate + Pyruvate

4-Hydroxyphenylpyruvate
GM trait affecting HPPD

p-HPPD(Intermediates)

Homogentisate
2-Demethylphytolplastoquinone

2-Demethylplastoquinone

Vitamin EPlastoquinone

Phytoene
Cofactor
For PDS

Phytoene
Desaturase(PDS)
Phytofluene
Vitamin A precursors

HPPD = hydroxyphenylpyruvate dioxygenase

Inside blue circles: metabolites that are hypothesized to be affected by the GM trait

2) Determine what nutritional components
should be quantified:

Crude protein
FibersAmino acids
Fatty acids
Minerals
Etc.

2-Demethylplastoquinone
2Vitamin E DemethylphytolVitamin A plastoquinoneprecursors

Homogentisate
Phytofluene

Plastoquinone

All compositional
components ofsoybean

Blue circle: components considered to be important for nutrition orsafety
Orange circle: components hypothesized to be affected by the GM
trait(s) of interest
Circle overlap area: those components to be included in the nutritional
assessment3) Evaluate safety implications of any observedchangeThe learnings and experience over the past 25 years now suggest a hypothesis
driven step-wise approach to evaluate the compositional safety of GM crops