Transcript ENVI 30 Environmental Issues

I.
Genetic Engineering
G.
Benefits and Risks
1.
Benefits
•
a.
b.
Accelerated improvement of crop strains
Elevated yields, either per plant or per acre
•
Usually involves inserting growth factor
•
Plants grow larger, faster or both
•
Con – Accelerated growth may alter chemical
composition  Allergies, digestive problems, etc.
Accelerated maturation process
•
Increased yield per acre, more crops per year
•
Con – Plants produce different compounds at
different life stages
•
Young plants tend to produce more irritants and
toxins (self defense)
•
Potential to cause digestive or allergic problems
I.
Genetic Engineering
G.
Benefits and Risks
1.
Benefits
c.
d.
Increased resistance to disease, pests, toxins
•
Reduced losses  Greater yield
•
Reduced application of chemicals
•
Con – Potential transfer of resistance genes to
weedy plant species through pollination
•
Less problematic in areas where crop plants don’t
have wild relatives
•
Con – Development of resistance in pests
Increased longevity of harvested produce
•
Resistance to spoilage
•
Ex – Potato engineered with bacterial gene for
antifungal properties
•
Helps potatoes to stay in storage without rotting
•
Con – Chemicals that resist decomposition likely to
be more difficult to digest
I.
Genetic Engineering
G.
Benefits and Risks
1.
Benefits
e.
f.
Increased resistance to cultural extremes
•
Ex – Insertion of Arctic flounder antifreeze protein
genes into strawberry
•
Confers greater frost resistance and better fruit
storage properties
•
Con – Potential transfer of antifreeze genes to weedy
plant species
Increased nutritional value
•
Ex – High starch potato that absorbs less oil when
cooking (low fat potato chips)
•
Ex – Canola oil (Laurical®) with healthier
composition
•
Con – Unknown effects of eating modified foods
•
Ex – Insertion of Brazil nut gene into soybeans to
increase protein content
•
Many people allergic to Brazil nuts
I.
Genetic Engineering
G. Benefits and Risks
1.
Benefits
g.
Reduced dependence on chemical fertilizers
•
More efficient growth  lower use of fertilizer
•
American farmers spend >$12 billion a year on
chemical fertilizers
•
50% or more of fertilizer applied to crops is not
absorbed and enters runoff  water pollution
•
Con – Transfer of genes for greater growth
efficiency to weeds could be disastrous
•
Con – Substitution of dependence on big
western agribusiness
I.
Genetic Engineering
G.
Benefits and Risks
2.
Risks
a.
Unexpected effects
•
May or may not be beneficial
•
Ex – Klebsiella planticola (soil bacterium) engineered
to transform plant residue into ethyl alcohol (fuel)
•
GM strain in soils produced EtOH, leading to
poisoning of grasses and decrease in populations of
beneficial mycorrhizal fungi
•
Ex – Pseudomonas putida (bacterium) engineered to
degrade 2,4-D (herbicide)
•
Breakdown products highly toxic to fungi, including
mycorrhizae
•
Ex – Bacillus thuringiensis (Bt) toxin may bind to soil
particles, slowing degradation and maintaining
toxicity for longer than expected