Biotechnology
and Climate Change
The
continuing increase in greenhouse gas emissions raises the temperature of the
earth’s atmosphere. This results to melting of glaciers, unpredictable rainfall
patterns, and extreme weather events. The accelerating pace of climate change,
combined with global population and depletion of agricultural resources threatens
food security globally.
The
over-all impact of climate change as it affects agriculture was described by
the Intergovernmental Panel on Climate Change (IPCC, 2007), and cited by the US
EPA (2011)1 to be as follows:
Increases
in average temperature will result to: i)
increased crop productivity in high latitude temperate regions due to
the lengthening of the growing season; ii)
reduced crop productivity in low latitude subtropical and tropical
regions where summer heat is already limiting productivity; and iii) reduced
productivity due to an increase in soil evaporation rates.
Change
in amount of rainfall and patterns will affect soil erosion rates and soil
moisture, which are important for crop yields. Precipitation will increase in
high latitudes, and decrease in most subtropical low latitude regions – some by
as much as about 20%, leading to long drought spells.
Rising
atmospheric concentrations of CO2 will boost and enhance the growth of some
crops but other aspects of climate change (e.g., higher temperatures and
precipitation changes) may offset any beneficial boosting effect of higher CO2
levels.
Pollution
levels of tropospheric ozone (or bad ozone that can damage living tissue and
break down certain materials) may increase due to the rise in CO2 emissions.
This may lead to higher temperatures that will offset the increased growth of
crops resulting from higher levels of CO2.
Changes
in the frequency and severity of heat waves, drought, floods and hurricanes,
remain a key uncertain factor that may potentially affect agriculture.
Climatic
changes will affect agricultural systems and may lead to emergence of new pests
and diseases.
In
2012, almost 40% of the world population of 6.7 billion, equivalent to 2.5
billion, rely on agriculture for their livelihood and will thus likely be the
most severely affected. 2
To
mitigate these effects, current agricultural approaches need to be modified and
innovative adaption strategies need to be in place to efficiently produce more
food in stressed conditions and with net reduction in greenhouse gas emissions.
Contribution
of Biotech Crops in Mitigating Effects of Climate Change
Green
biotechnology offers a solution to decrease green house gases and therefore
mitigates climate change. Biotech crops for the last 16 years of
commercialization have been contributing to the reduction of CO2 emissions.
They allow farmers to use less and environmentally friendly energy and
fertilizer, and practice soil carbon sequestration.
Herbicide
tolerant biotech crops such as soybean and canola facilitate zero or no-till,
which significantly reduces the loss of soil carbon (carbon sequestration) and
CO2 emissions, reduce fuel use, and significantly reduce soil erosion.
Insect
resistant biotech crops require fewer pesticide sprays which results in savings
of tractor/fossil fuel and thus less CO2 emissions. For 2011, there was a
reduction of 37 million kg of active ingredients, decreased rate of herbicide
and insecticide sprays and ploughing reduced CO2 emission by 23.1 billion kg of CO2 or removing 10.2 million
cars off the road.3
Biotech
Crops Adapted to Climate Change
Crops
can be modified faster through biotechnology than conventional crops, thus
hastening implementation of strategies to meet rapid and severe climatic changes.
Pest and disease resistant biotech crops have continuously developed as new
pests and diseases emerge with changes in climate. Resistant varieties will
also reduce pesticide application and hence CO2 emission. Crops tolerant to various abiotech stresses
have been developed in response to climatic changes.
Salinity
Tolerant Crops
Biotech
salt tolerant crops have been developed and some are in the final field trials
before commercialization. In Australia, field trials of 1,161 lines of
genetically modified (GM) wheat and
1,179 lines of GM barley modified to contain one of 35 genes obtained from
wheat, barley, maize, thale cress, moss or yeasts are in progress since 2010
and will run till 2015. Some of the genes are expected to enhance tolerance to
a range of abiotic stresses including drought, cold, salt and low phosphorous.
Sugarcane that contains transcription factor (OsDREB1A) is also under field
trial from 2009 to 2015.4
More
than a dozen of other genes influencing salt tolerance have been found in
various plants. Some of these candidate genes may prove feasible in developing
salt tolerance in sugarcane 4, rice5,6, barley 7, wheat 8, tomato9, and
soybean10.
Drought
Resistant Crops
Transgenic
plants carrying genes for water-stress management have been developed. Structural genes (key enzymes for osmolyte
biosynthesis, such as proline, glycine/betaine, mannitol and trehalose, redox
proteins and detoxifying enzymes, stress-induced LEA proteins) and regulatory
genes, including dehydration–responsive, element-binding (DREB) factors, zinc
finger proteins, and NAC transcription factor genes, are being used. Transgenic
crops carrying different drought tolerant genes are being developed in rice,
wheat, maize, sugarcane, tobacco, Arabidopsis, groundnut, tomato, potato and
papaya.11, 12
An
important initiative for Africa is the Water Efficient Maize for Africa (WEMA)
project of the Kenyan-based African Agricultural Technology Foundation (AATF)
and funded by the Bill and Melinda Gates Foundation (BMGF) and Howard G. Buffet
Foundations. Drought tolerant WEMA varieties developed through marker assisted
breeding could be available to farmers within the next two or three years.
Drought-tolerant and insect-protected varieties developed using both advanced
breeding and transgenic approaches could be available to farmers in the later
part of the decade.13 In 2012, a genetically modified drought tolerant maize
MON 87460 that expresses cold shock protein B has been approved in the US for
release in the market.14
Biotech
Crops for Cold Tolerance
By
using genetic and molecular approaches, a number of relevant genes have been
identified and new information continually emerges. Among which are the genes
controlling the CBF cold-responsive pathway and together with DREB1 genes,
integrate several components of the cold acclimation response to tolerance low
temperatures.15
Cold
tolerant GM crops are being developed such as GM eucalypti, which is currently
being field tested in the US by Arborgen LLC since 2010. Thale cress has been
improved to contain the DaIRIP4 from Deschapsia antarctica, a hairgrass that thrives
in frosts down to -30C, and sugarcane are being introgressed with genes from
cold tolerant wild varieties.4
Biotech
Crops for Heat Stress
Expression
of heat shock proteins (HSPs) has been associated with recovery of plants under
heat stress and sometimes, even during drought. HSPs bind and stabilize
proteins that have become denatured during stress conditions, and provide
protection to prevent protein aggregation. In GM chrysanthemum containing the
DREBIA gene from Arabidopsis thaliana, the transgene and other heat responsive
genes such as the HSP70 (heat shock proteins) were highly expressed when
exposed to heat treatment. The transgenic plants maintained higher
photosynthetic capacity and elevated levels of photosynthesis-related
enzymes.16
Forward
Looking
Improved
crops resilient to extreme environments caused by climate change are
expected in a few years to a decade.
Hence, food production during this era should be given another boost to sustain
food supply for the doubling population. Biotech research to mitigate global
warming should also be initiated to sustain the utilization of new products.
Among these are: the induction of nodular structures on the roots of
non-leguminous cereal crops to fix nitrogen. This will reduce farmers’ reliance
on inorganic fertilizers. Another is the utilization of excess CO2 in the air
by staple crop rice by converting its CO2 harnessing capability from C3 to C4
pathway. C4 plants like maize can efficiently assimilate and convert CO2 to
carbon products during photosynthesis.
References
US
EPA. 2011. Agriculture and Food Supply: Climate change, health and
environmental effects. April 14, 2011.
http://www.epa.gov/climatechange/effects/agriculture.html
IFPRI.
2009. Climate change impact on agriculture and cost adaptation.
http://www.ifpri.org/sites/default/files/publications/pr21.pdf
Brookes,
G and P Barfoot. 2012. Global economic and environmental benefits of GM crops
continue to rise. http://www.pgeconomics.co.uk/page/33/global-impact-2012
Tammisola,
J. 2010. Towards much more efficient biofuel crops – can sugarcane pave the
way? GM Crops 1:4; 181-198.
http://www.landesbioscience.com/journals/gmcrops/02TammisolaGMC1-4.pdf
http://thesecondgreenrevolution.blogspot.com/2012/02/salt-tolerant-gm-barley-trials-in.html
http://irri.org/index.php?option=com_k2&view=item&id=9952:drought-submergence-and-salinity-management&lang=en
Salt
Tolerant GM Barley Trials in Australia, Successful.
http://thesecondgreenrevolution.blogspot.com/2012/02/salt-tolerant-gm-barley-trials-in.html
http://www.grdc.com.au/director/research/prebreeding?item_id=E31810F9A59C5C8E62BAE7
518CD28067&pageNumber=1&filter1=&filter2=&filter3=&filter4=
Moghaieb
RE, A Nakamura, H Saneoka and K Fujita. 2011. Evaluation of salt tolerance in
ectoine-transgenic tomato plants (Lycopersicon esculentum) in terms of
photosynthesis, osmotic adjustment, and carbon partitioning. GM Crops.
2(1):58-65. http://www.ncbi.nlm.nih.gov/pubmed/21844699
http://www.springerlink.com/content/h51n73352374v877/.
http://bioeconomy.dk/outcome/presentations/27-march/panel-discussion-building-global-bioeconomy/zhang-yis-presentation
http://www.tandfonline.com/doi/abs/10.1080/15427520802418251#preview
http://www.monsanto.com/ourcommitments/pages/water-efficient-maize-for-africa.aspx
http://www.aphis.usda.gov/newsroom/2011/12/brs_actions.shtml
Sanghera,
GS, S H Wani, W Hussain, and N B Singh. 2011. Engineering cold stress tolerance
in crop plants. Curr Genomics 12 (1): 30-43.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3129041/?tool=pubmed
