10/17/2013 The American Society of Plant Biologists · The Plant Cell, October 2013 © 2013 The American Society of Plant Biologists 10/17/2013 3

The Plant Cell, October 2013 © 2013The American Society of Plant Biologists

10/17/2013

www.plantcell.org/cgi/doi/10.1105/tpc.111.tt0511 1

© 2013 American Society of Plant Biologists

Genetic Improvements in Agriculture

From Hunter Gatherer to Green Revolution and Beyond

www.plantcell.org/cgi/doi/10.1105/tpc.111.tt0511© 2013 American Society of Plant Biologists

Image credit: Smithsonian Institution Human Origins Program

•Life on earth is about four billion years old•Homo sapiens emerged as a species about 300,000 years ago

Cro magnon skull Homo sapiens

~ 30,000 years old


•Human activities have caused vast changes in the physical, chemical, geological, atmospheric and biological realm of our planetCro magnon skull

Homo sapiens~ 30,000 years old

Image credit: Smithsonian Institution Human Origins Program


We’ve removed mountains

1984 2009

The Hobet coal mine in Boone County, West Virginia spreads over 10,000 acres (15.6 square miles)

NASA images by Robert Simmon, based on Landsat 5 data from the USGS Global Visualization Viewer.

2 km

1987

2006

Photo credit: NASA/Goddard Space Flight Center Scientific Visualization Studio United States Geological Survey and Le Grand Portage

+ View movie of the dam's

construction

Three Gorges Dam, the world's largest hydroelectric power generator. The reservoir just upstream of the dam is more than 2 miles (3 km) across

...dammed rivers...

Dodo by Edouard Poppig, 1841

The dodo (Raphus cucullatus) was a large flightless bird indigenous to Mauritius. The arrival of humans led to the dodo’s extinction by the end of the 17th century.

....caused extinctions.....


...modified other species in extraordinary ways

?


... and modified plant genomes for thousands of years......

Image credits: P. Cos, Cacaphony, USDA, CIMMYT


1850 1900 1950 20001800

Atmospheric CO2

500 1000 1500 20000

Global population

Now we face our biggest challenges

How do we feed more people without further damaging our planet?

Photo courtesy Earth Observatory NASA


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How do we feed more people with fewer resources available?

Fess et al. (2011) Crop breeding for low input agriculture: a sustainable response to feed a growing world population. Sustainability 3: 1742-1772Photo courtesy Earth Observatory NASA


What is the role of plant breeding in addressing global challenges?

Photo credits: Xochiquetzal Fonseca/CIMMYT and IRRI


• The Distant Past

• Crop plant domestication and beyond

• The Recent Past

• Hybrid seed

• The (First) Green Revolution

• Advances in breeding technologies

• Now and Into The Future

• Breeding for improved human health

• Breeding for drought tolerance

• Agricultural innovation in Africa

• The Second Green Revolution

GENETIC IMPROVEMENTS IN AGRICULTURE


The Distant Past (>10,000 years ago to 1900)

Karol Schauer

• Homo sapiens originated 400,000 –250,000 years ago

• Major crops were domesticated ~ 10,000 –5000 years ago

• The development of human civilizations is correlated with the development of agriculture


Plant domestication followed the end of the most recent glacial period

Allaby, R.G., Fuller, D.Q., and Brown, T.A. (2008) The genetic expectations of a protracted model for the origins of domesticated crops. Proc. Natl. Acad. Sci. USA 105: 13982-13986, copyright National Academy of Sciences USA

Glacial retreatGlacial advance

Wild gathering Pre-domestication cultivation

Domestication

Neolithic Revolution

thousand years ago


How did people begin to cultivate plants?

X X

X

It is thought to have been a gradual change from seeking and following food sources


X

X


It is thought to have been a gradual change from seeking and following food sources to semi settled migration


X


It is thought to have been a gradual change from seeking and following food sources to semi settled migration and finally permanent settlements.


Plants were domesticated in parallel in several regions

Reprinted by permission from Macmillan Publishers Ltd.: [Nature] Diamond, J. (2002). Evolution, consequences and future of plant and animal domestication. Nature 418: 700-707, copyright 2002.

Wheat, barley, pea, lentil~ 13,000 years ago

Rice, soybean ~ 9000 years ago

Rice, bean ~ 8500 years ago

Corn, squash, bean, potato ~ 10,000 years ago


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Genetic modification arose as a consequence of cultivation

Natural variation within population

Image courtesy of University of California Museum of Paleontology, Understanding Evolution - www.evolution.berkeley.edu

Planting seeds from “good” plants increased their representation in subsequent generations


During maize domestication cobsize increased

Photo © Robert S. Peabody Museum of Archaeology, Phillips Academy, Andover, Massachusetts. All Rights Reserved.

Cobs from archeological

sites in the Valley of Tehuacan,

Mexico

7000 years ago

500 years ago


The hard casings around many grains were eliminated

Photo by Hugh Iltis; Reprinted from Doebley, J.F., Gaut, B.S., and Smith, B.D. (2006). The Molecular Genetics of Crop Domestication. Cell 127: 1309-1321, with permission from Elsevier.

Teosinte, the wild relative of maize, has hard coverings over each grain. Humans selected against these during maize domestication.


Decrease in branching and increase in seed size were also selected for

Image credit Nicolle Rager Fuller, National Science Foundation


Seeds that don’t break off were selected

WildShattering grain“Brittle rachis”Advantage –maximizes seed dispersal

DomesticatedNon-shattering grain

“Tough rachis”Advantage –

facilitates harvesting

From Konishi, S., Izawa, T., Lin, S.Y., Ebana, K., Fukuta, Y., Sasaki, T., and Yano, M. (2006). An SNP caused loss of seed shattering during rice domestication. Science 312: 1392-1396. Reprinted with permission from AAAS.


Many of our crops are products of extensive genomic rearrangements

From Dubcovsky, J. and Dvorak, J. (2007). Genome Plasticity a Key Factor in the Success of Polyploid Wheat Under Domestication. Science. 316: 1862-1866. Reprinted with permission from AAAS. Brassica figure from Adenosine

Common wheat is the result of interspecific hybridization between

three ancestors

Polyploid (multi-genome) plants are often bigger and so

selected for propagation

The brassicas share three genomes recombined in various ways


Domestication through genome modification gave us modern crops

From Dubcovsky, J. and Dvorak, J. (2007). Genome Plasticity a Key Factor in the Success of Polyploid Wheat Under Domestication. Science. 316: 1862-1866. Reprinted with permission from AAAS.

PA CHIAMSERAUP

FORTUNA BESAR 15 M ARONG UNKNOWNPAROC

BLUE ROSE

BPI 76 REXORO SUPREM EKITCHILI SAM BA

SINAWPAGH

UNKNOWNCINA LATISAIL TEXAS RSBR GEB24

PATNA BLUE BONNETPETA

DGWG CP231 SLO 17 BENONG

IR86 CP SLO 17 SIGADIS

IR95IR127

IR8 CHOW SUNG IR262

IR1103 TADUKAN VELLAIKARIR400 TSAI YUAN CHUNG

IR1006 M UDGOTETEP

IR1163 IR238 TN1

IR1416 IR1641IR1402

IR22 TKM 6 IR746AIR1704

O. nivaraIR1870 IR1614

IR2006 IR579 IR747 IR24/ IR661 IR1721

IR773 A BPI 121 GAM PAI

IR1915 B IR1833 GAM PAI 15 IR1561 IR1737

IR1916 IR833 IR2040

IR2146 IR 2055IR2061

IR5236 IR5338 Ultimate LandracesGAM PAI TSAI YUAN CHUNG

IR5657 DEE GEO WOO GEN BENONGCINA Unknow n

IR18348 LATISAIL CHOW SUNGTADUKAN MUDGO

IR64 KITCHILI SAMBA TETEPPA CHIAM SINAWPAGHSERAUPBESAR 15 UNKNOWN (JAPANESE)NAHNG MON S 4 O. nivara (IRGC 101508)VELLAIKAR MARONG PAROC

CO 18

NAHNG M ON S4

NM S 4

IR 64

original rice genome

Mutations

Recombinations Translocations

Deletions

Inversions

One of the most widely grown crops, indica rice IR64 is the product of a complex breeding program that has caused extensive genomic modification, mutation, deletion and rearrangement

Slide courtesy of Ingo Potrykus


The myth of natural food

The food we eat comes from plants already extensively modified from their original form. Even heritage varieties are extensively genetically modified.

Credit: Nicolle Rager Fuller, National Science Foundation


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The Recent Past –Scientific Plant Breeding

The twentieth century took us from gas lamps to Google and steamships to space shuttles


6 billion

1.6 billion

1234567

1300 1400 1500 1600 1700 1800 1900 2000

World Population (billions)

The twentieth century took us from gas lamps to Google and steamships to space shuttles

And the world population

quadrupled in just over 100 years




Improvements in plant propagation and breeding were needed to keep up with population growth

Photo credits: Gartons Plant Breeders


Mendel and Darwin paved the way for scientific plant breeding


The development of hybrid corn led to a big increase in yields

A BB x A A x B

The progeny of two genetically different parents often show enhanced growth – this effect is termed “hybrid vigor” (also known as heterosis)

Shull, G.H. (1909) A pure line method in corn breeding. Am. Breed. Assoc. Rep. 5, 51–59 by permission of Oxford University Press.


Hybrid corn was rapidly adopted because of its increased yields

A BB x A A x B

Percentage of total corn acreage

Even though farmers had to purchase seed every year, increased yields more than

offset increased costs

Shull, G.H. (1909) A pure line method in corn breeding. Am. Breed. Assoc. Rep. 5, 51–59 by permission of Oxford University Press.


Norman Borlaug, “father of the green revolution”

Distinguished plant breeder and Nobel LaureateNorman Borlaug 1914-2009

One of the most significant accomplishments of 20th

century science was the development of lodging-resistant, high-yielding semi-dwarf grain varieties


Improved green-revolution plants dramatically increased crop yields

The introduction of disease-resistant,

semi-dwarf varieties turning countries from

grain importers to grain exporters

Source: FAO via Brian0918

Dwarf wheat was developed at CIMMYT – the International Maize and Wheat Improvement Center


CGIAR is an international organization of agricultural research groups


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Rice breeding at IRRI also brought huge yield increases

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

1961 20001980

World rice yield (ton/ha) (FAO)

Photo courtesy IRRI

IR8, released in 1966, “…was to tropical rices what the Model T Ford was to automobiles.” It was

known as “miracle rice” because of its high yields.


Crop productivity has kept pace with population because of increased

yields

Burney, J.A., Davis, S.J., and Lobell, D.B. (2010). Greenhouse gas mitigation by agricultural intensification. Proc. Natl. Acad. Sci. 107: 12052-12057.

Population (billions) Crop area (hectare)Crop production (gigaton)

Crop area has not increased as rapidly as crop production, because yields (food per hectare) have increased

Growing more food without using more land helps mitigate climate change and slow the loss of biodiversity

100% increase

>100% increase

~20% increase


Modern plant breeders use molecular methods including DNA

sequencing and proteomics as well as field studies

Photo credits Scott Bauer USDA; CIMMYT; IRRI; RCMI; Duke Institute for Genome Sciences and Policy


Advances in genetic technologies contribute to improved plants

• Marker assisted selection • Genome-wide association studies• Recombinant DNA technology and transgenic plants• Cisgenics and intragenics• Transgrafting• Precision genome editing

Photo credit: IRRI


Marker assisted selection (MAS)

Phenotype: physical expression of traits

Genotype: sequence of all the genes in a genome

Photo credit LemnaTec; Anderson, L.K., Lai, A., Stack, S.M., Rizzon, C. and Gaut, B.S. (2006). Uneven distribution of expressed sequence tag loci on maize pachytene chromosomes. Genome Research. 16: 115-122.


Marker assisted selection (MAS)

Phenotype: physical expression of traits

Genotype: sequence of all the genes in a genome

Selecting for DNA markers is faster than

selecting for phenotype

Photo credit LemnaTec; Anderson, L.K., Lai, A., Stack, S.M., Rizzon, C. and Gaut, B.S. (2006). Uneven distribution of expressed sequence tag loci on maize pachytene chromosomes. Genome Research. 16: 115-122.


How markers work: Each generation, genes reassort or shuffle

Markers let us “see” which genes each

individual has inherited


Example: Introgression of a disease resistance gene

Elite tomato Poor tomato but disease resistant (resistance gene indicated)

We want to add a disease resistance trait to an “elite” tomato plant.



We cross the two plants. Some of their progeny inherit the disease resistance trait, some don’t – how can we tell the difference?

Photo by Stephen Ausmus USDA


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We can use markers to look at their DNA and identify those with the resistance gene.It’s faster and easier than infecting them to see the phenotype



Is this an elite, disease-resistant tomato? No, half of its genes are from the poor tomato



We have to repeatedly cross back to the elite tomato, using markers to identify plants with the disease resistance gene



After several generations, elite, disease resistant tomato

Markers greatly accelerate breeding

programs


MAS as a tool in production of submergence tolerant rice (Sub1)

Many rice-growing regions are prone to flooding. In Pakistan a 2010 a huge, deadly, flood submerged 17 million acres (69,000 km2) and destroyed much of the harvest

Photo credits: Abdul Majeed Goraya / IRIN; NASA Goddard

July 2010

Sept. 2010

50 km


Submergence-tolerant rice can survive floods as long as 17 days

Sensitive rice – cannot survive prolonged flooding

Submergence-tolerant Sub1 rice – growth arrests during flooding, enhancing survival

FLOODING Water retreats


Production of Swarna–Sub1:Cross Swarna with Sub1 donor

After several generations, Swarna-Sub1

Swarna

Sub1

Swarna is a high-yielding rice variety but sensitive to flooding


Reprinted by permission from Macmillan Publishers Ltd. (NATURE) Xu, K., Xu, X., Fukao, T., Canlas, P., Maghirang-Rodriguez, R., Heuer, S., Ismail, A.M., Bailey-Serres, J., Ronald, P.C., and Mackill, D.J. (2006). Sub1A is an ethylene-response-factor-like gene that confers submergence tolerance to rice. Nature 442: 705-708. Photo couresy of Adam Barclay CPS, IRRI Photo.

Swarna –high yielding,flooding sensitive

Submergence tolerant parent

Swarna-Sub1

MAS allowed the Sub-1 trait to be rapidly introgressed into Swarna. The Swarna-Sub1 rice accounted for over ¼ of the rice planted in India in 2010.


Advances in genomics technologies facilitate breeding for complex traits

•Genome sequence data are available for more than 20 plant species•Molecular breeding and mapping tools are developed for many species•Genome-wide association studies help match genes to traits

Anderson, L.K., Lai, A., Stack, S.M., Rizzon, C. and Gaut, B.S. (2006). Uneven distribution of expressed sequence tag loci on maize pachytene chromosomes. Genome Research. 16: 115-122.


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Genome sequence data are available for many important plants

Maize


Phenotype analysis

Genotype analysis

Genome-wide methods make it possible to identify genes associated with complex traits, like yield or water use efficiency

Association analysis

Gene discovery


This approach allows hundreds of genes with small effects to be

identified

Reprinted by permission from Macmillan Publishers Ltd. Tian, F., Bradbury, P.J., Brown, P.J., Hung, H., Sun, Q., Flint-Garcia, S., Rocheford, T.R., McMullen, M.D., Holland, J.B., and Buckler, E.S. (2011). Genome-wide association study of leaf architecture in the maize nested association mapping population. Nat Genet 43: 159-162.

In maize, grain yields are correlated with leaf angle and size. A genome-wide association survey (GWAS) revealed hundreds of single-nucleotide polymorphisms (SNPs) associated with these traits, providing invaluable information for breeders.


GWAS reveals SNPs that contribute to disease resistance

Reprinted by permission from Macmillan Publishers Ltd Kump, K.L., Bradbury, P.J., Wisser, R.J., Buckler, E.S., Belcher, A.R., Oropeza-Rosas, M.A., Zwonitzer, J.C., Kresovich, S., McMullen, M.D., Ware, D., Balint-Kurti, P.J., and Holland, J.B. (2011). Genome-wide association study of quantitative resistance to southern leaf blight in the maize nested association mapping population. Nat Genet 43: 163-168.

Similar studies have led to the identification of genes contributing to other agronomicallyimportant traits including drought tolerance


Genetic Modification (GM) is another breeding method

Elite tomato Disease resistant plant (need not be same species)

Elite, disease resistant tomato

Recombinant DNA (or GM) allows a single

gene to be introduced into a genome. This

method can be faster than conventional

breeding


Source of gene (disease-resistant

plant)

Gene of interest

Isolate gene of interest using molecular biology methods

Recombine into recipient plant DNA

Once a gene is introduced into the plant genome it functions like any other gene


Molecular breeding

Why use GM methods sometimes and molecular breeding others?

1. Desired trait must be present in population

2. Genetic resources must be available

3. Plant should be propagated sexually

Photo credits: Gramene.org


Why use GM methods sometimes and molecular breeding others?

Molecular breeding

1. Desired trait must be present in population

2. Genetic resources must be available

3. Plant should be propagated sexually

GM

1. Gene can come from any source

3. Plant can be propagated vegetatively2. Genetic resources not

requiredPhoto credits: Gramene.orgPhoto credits: Gramene.org ETH Life International


GM Example: Disease resistant banana via pepper gene

Resistant SusceptibleBanana bacterial wilt (Xanthomonas campestris pv. musacearum) is destroying plants in eastern Africa. Transgenic plants carrying a resistance gene from pepper are resistant to the disease

Tripathi, L., Mwaka, H., Tripathi, J.N., and Tushemereirwe, W.K. (2010). Expression of sweet pepper Hrap gene in banana enhances resistance to Xanthomonas campestris pv. musacearum. Molecular Plant Pathology 11: 721-731.


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GM Example: Insect resistance through introduction of the Bt gene

Wild-type peanut plant Peanut plant expressing the Bt gene

Photo by Herb Pilcher USDA


Bacillus thuringiensis (Bt) bacteria produce insecticidal proteins

Bacillus thuringiensis expressing Bt toxin

Plant cell expressing Bt

toxin

Bacillus thuringiensis expressing insecticidal Bt toxin can be sprayed onto plants

Or the plants can be engineered to express the Bt gene coding for Bt toxin


The effect of Bt toxin is highly specific



toxin

Intestine

The Bt toxin affects only some insects because to be effective it has to be processed and bind to a specific receptor protein

Processing

Receptor binding

Intestinal lumen


The effect of Bt toxin is highly specific



toxin

After binding, the insecticidal proteins assemble to form a pore in the lining of the insect intestine which kills the insect

Pore assembly

Intestine


Photo credit: Doug Buhler, Bugwood.org

Plants compete with other plants for sunlight and nutrients. Many farmers use herbicides to eliminate weeds (undesired plants) from their fields.

Left – corn rows sprayed with herbicide to eliminate competing plantsRight – corn being choked by giant foxtail (Setaria faberi)

GM Example: Herbicide resistance


Herbicide tolerant plants are environmentally friendly

Cerdeira, A.L. and Duke, S.O. (2006). The Current Status and Environmental Impacts of Glyphosate-Resistant Crops. J. Environ. Qual. 35: 1633-1658. Photo credit Hunt Sanders, University of Georgia, bugwood.org.

Farmers that plant herbicide-tolerant crop plants use less herbicide, herbicides that are less toxic, and till (plow) less, saving soil and fuel.

Soybean

*

*


Gene flow through pollen movement has to be monitored and controlled

Howard F. Schwartz, Colorado State University, Bugwood.org

There have been confirmed cases of gene transfer from crops to weeds and vice versa.• What consequences are

expected from gene flow?• How can gene flow be

minimized? • How can consequences be

mitigated?


Emerging technologies circumvent some concerns about transgenics

In the conventional approach to transgenic plant production, a large piece of DNA, derived from several sources, is inserted randomly into the genome

Open Reading Frame

5′ UTR 3′ UTRPromoter

Plant genome

Transgene cassette

The promoter, 5′ and 3′ untranslated regions (UTRs) and protein coding region may all come from different sources

All the cells carry the

transgene


Cisgenics: Genes from the same or closely-related species

Schouten, H.J., Krens, F.A. and Jacobsen, E. (2006). Cisgenic plants are similar to traditionally bred plants. EMBO Rep. 7: 750-753.

Apple gene

Apple geneApple gene

That might mean that little foreign DNA is introduced (“cisgenic”)

Some traits can be modified by the introduction of a cisgene –a gene from the same or closely-related species

Or, bacterial and viral DNA may be included, but no protein-coding regions from other organisms (“intragenic”)

Small amounts of DNA from T-DNA borders may be incorporated


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Cisgenics can add or silence genes

RNA silencing

ON

OFF

Resistance gene

One application of cisgenics is to add resistance genes

Advantages: Avoids lengthy backcrossing processParticularly useful for plants propagated vegetatively, such as potato or apple

Disadvantages: Gene must exist in gene pool

Gene silencing can be induced by introduction of antisense or hairpin RNA,

or overexpression of an endogenous gene

Silencing construct

The gene that causes cut apples to turn brown can be silenced

See for example Arctic Apple


Transgrafting: Wild-type tissues grafted to transgenic tissues

Transgrafting: A non-transgenic shoot can be grafted onto transgenic root, so the food products and pollen don’t carry the transgene

Transgenes can include those conferring root-specific traits e.g., pathogen resistance or nutrient uptake

Or, the roots can produce mobile factors such as small RNAs or proteins that affect the shoot’s phenotype

See Liang, D., White, R.G. and Waterhouse, P.M. (2012). Gene silencing in Arabidopsis spreads from the root to the shoot, through a gating barrier, by template-dependent, nonvascular, cell-to-cell movement. Plant Physiol. 159: 984-1000; McGarry, R.C. and Kragler, F. (2013). Phloem-mobile signals affecting flowers: applications for crop breeding. Trends Plant Sci. 18: 198-206.


Several new methods are available for precise genome engineering

From Jinek, M., Chylinski, K., Fonfara, I., Hauer, M., Doudna, J.A. and Charpentier, E. (2012). A programmable dual-RNA–guided DNA endonuclease in adaptive bacterial immunity. Science. 337: 816-821 with permission from AAAS; see also Bhaya, D., Davison, M. and Barrangou, R. (2011). CRISPR-Cas Systems in Bacteria and Archaea: Versatile small RNAs for adaptive defense and regulation. Annu. Rev. Genet. 45: 273-297.

Zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs) are proteins that can produce double-strand DNA breaks that when repaired introduce site-specific mutations or insertions

The clustered regularly interspaced short palindromic repeats (CRISPR) / CRISPR-associated (Cas) system uses RNAs to target nucleases to specific sites; when repaired, site-specific mutations or insertions are introduced


ZFNs and TALENs can be programmed to cleave specific sites

Reprinted from Gaj, T., Gersbach, C.A. and Barbas, C.F. (2013). ZFN, TALEN, and CRISPR/Cas-based methods for genome engineering. Trends Biotech. 31: 397-405 with permission from Elsevier.

ZFNs recognize 3-basepair sequences. A series of four linked ZFNs has a 12-bp binding specificity

TALENs recognize DNA via a series of 33 – 35 amino acid domains that each recognizes a single DNA basepair

The CRISPR / Cas system used RNA for targeting: cheaper than proteins


Repair of the resulting double-strand breaks causes mutations / insertions

Reprinted by permission from Macmillan Publishers Ltd: from Nekrasov, V., Staskawicz, B., Weigel, D., Jones, J.D.G. and Kamoun, S. (2013). Targeted mutagenesis in the model plant Nicotiana benthamiana using Cas9 RNA-guided endonuclease. Nat Biotech. 31: 691-693.

Targetted cleavage

Template DNA

Repair in the presence of template DNA can lead to insertion of new sequences

Repair of the ds breaks can lead to small insertions and deletions

Wild-type sequence

Repair products showing deletions, insertions, and replacements


These and other new approaches are becoming increasingly important

Reprinted by permission from Macmillan Publishers Ltd. From Lusser, M., Parisi, C., Plan, D. and Rodriguez-Cerezo, E. (2012). Deployment of new biotechnologies in plant breeding. Nat Biotech. 30: 231-239.


Photo credit: IRRI

Future Challenges


Breeders can use more than one technology to address a challenge

PROBLEM

SOLUTIONPublic –private

partnerships

MAS breeding

Gene pyramiding

Improved agronomic practices

GM technology

Genome-wide

association


Breeding plants for β-carotene (pro-vitamin A) enrichment

Image sources: Petaholmes based on WHO data;

Vitamin A deficiency is a leading cause of blindness


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Enhanced β-carotene content in food can prevent vitamin A

deficiency

Vitamin Aβ-carotene

β-carotene is converted to vitamin A in the human body

•Many staple foods are poor sources of β-carotene so many people do not get adequate vitamin A in their diet


Synthesis, storage and breakdown all affect β-carotene content

Vitamin A

To increase beta-carotene levels in plants, you need more synthesis, more storage or less catabolism

GGPP

phytoene

lycopene

β-carotene

Synthesis

StorageCatabolism

or conversion

to other forms

Chromoplasts –organelles that store

carotenoids

Photo credit: University of Wisconsin


β-carotene makes the rice

look golden

Vitamin A

Photo credit: Golden rice humanitarian board

β-carotene

The β-carotene enriched foods

shown here have been

produced using GM and non-GM

approaches

There is no inherently right or wrong way to enhance plant

nutritional quality


Biofortified plants are improving nutrition for many

The non-profit organization HarvestPlus focuses on the development of biofortified crops for the developing world, including a provitamin A enriched sweet potato that is currently being grown by half a million families. Other biofortification projects are underway to increase levels of protein, iron, zinc, antioxidants and other beneficial components in food.

Sources: HarvestPlus; CIMMYT


Breeding for drought tolerance

Water use efficiency is a complex trait that involves hundreds of genes

Photo credit: J.S. Quick, Bugwood.org


Food production for one person for one day requires 3000 liters of water

Comprehensive Assessment of Water Management in Agriculture. 2007. Water for Food, Water for Life: A Comprehensive Assessment of Water Management in Agriculture. London: Earthscan, and Colombo: International Water Management Institute.

Global water withdrawal (km3/yr)

70% of water usage is for agriculture


The incidence of major droughts is on the rise

China experienced a major drought in 2011

Extreme

Severe

Moderate

Image credits: USDA Foreign Agricultural Service; IRRI; NASA earth observatory, USDA Farm Service Agency

Major droughts and heat waves in China, Russia, the U.S. and Australia have impacted food production and raised prices

Russia experienced heat waves, drought and wildfires in 2010


In 2011 seed companies released water-optimized corn

Both of these varieties were developed using modern molecular breeding methods

without the use of recombinant DNA


Agricultural innovation in Africa –breeding crops for sub-Saharan

Africa

0-1

1-2

2-3

3-4

4-5

5-6

6-7

7-8

Fertility rateBirth rates are high and crop yields are low so many African countries are not currently self-sufficient


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Many African countries experience a very high rate of undernourishment

Source: FAOSTAT


The challenges to food production in Africa are immense

• Lack of infrastructure, especially irrigation and access to transportation networks

• High incidence of diseases • Lack of available fertilizers• Lack of education and support for

farmers• Lack of economic supports and market

stability• Agricultural subsidies in other countries

affect market value


Maize is a staple crop in Africa but very sensitive to drought damage

Less than 10% of crop land in sub-Saharan Africa is irrigated, making agriculture production highly susceptible to drought

Photo credit: Anne Wangalachi/CIMMYT Map Source – FAO Aquastat 2005

Irrigation as percentage of cultivated area


As a consequence of climate changes, droughts are expected to increase

Image credit: United Nations Economic Commission for Africa, 2008 Africa Review Report on Drought and Desertification

In some African countries, yields from rain-fed agriculture, which is important for the poorest farmers, could be reduced by up to 50% by 2020.

-(FAO 2010)

Water-efficient maize optimized for growth in sub-Saharan Africa (WEMA) has been developed through a

combination of breeding and GM methods

WEMA is being developed as a public-private partnership that includes international

and regional plant breeding institutes,

philanthropic groups and Monsanto

Photo credits: Anne Wangalachi/CIMMYT

Water Efficient Maize for Africa (WEMA) was developed through a public-private partnership


Plant breeding can support African agriculture

African farmers need access to high yielding,

drought tolerant, disease resistant

plants. Most food is grown by small-

scale farmers with little mechanization. Cassava, cowpea and banana are

important crops and the focus of

intensive breeding programs.

Photos courtesy if IITA


African governments are working together to support agriculture

“AGRA is a dynamic, African-led partnership working across the African continent to help millions of small-scale farmers and their families lift themselves out of poverty and hunger”. A major thrust of these efforts is to develop Africa’s human capacity through education, innovation and technology transfer.

Alliance for a Green Revolution in Africa

Source: AGRA


In the next 50 years, we will have to produce as much food as we have yet produced in human history

Photo credit: © UNICEF/NYHQ1998-0891/Giacomo Pirozzi


We have many paths to follow

PROBLEMS

SOLUTIONS

Increased water use efficiency

Improved nutrient content

Higher yields

Stress tolerance

Disease resistance

Improved fertilizer uptake


10/17/2013



Breeding crops for a second green revolution

Many people are calling for a second green revolution, to develop plants that minimize environmental degradation while enhancing human health.

Advances in genetics make that possible.

Photo credit: IRRI


What risk assessments are performed on GM crops?

Before release into the environment, GM crops are subject to risk-assessment and risk-management measures to evaluate:• Risks to human health (including toxicity and allergenicity)• Risks of evolution of resistance in target pathogens or pests• Risks to non-target organisms • Risks from movement of transgenes


Will genes from GMOs contaminate wild populations?

John William Waterhouse: Pandora - 1896

When Pandora opened the forbidden box she released

evil into the world

Pollen can move DNA between plants. To minimize this possibility, GM crops have to be grown prescribed distances away from closely related plants. Technological methods to reduce this risk are being developed.


Will anti-insecticidal genes harm unintended targets?

Image credit jons2

The evidence shows that the planting of GE crops has largely resulted in less adverse or equivalent effects on the farm environment compared with the conventional non-GE systems that GE crops replaced (National Academies 2010)


Photo credit: CIMMYT.

Partnerships including national agricultural research institutions, non-government and community-

based organizations, regional research networks, and private

companies work together to develop seeds that are suited to

local conditions and are affordable for local farmers

> 45% of corn yields are often lost to insects

Will GMOs take away choice and exploit small farmers?


Are GM crops safe to eat?

YES

Photo credit: Neil Palmer/ CIAT

All GM plants are subject to extensive testing and

regulatory oversight and no detrimental health effects

have been identified

Bt corn is less prone contamination by fungi which

produce toxins linked to cancer and birth defects

GM biofortification can ensure that all children get adequate levels of protein, vitamins and mineral nutrients.

GM is a safe and beneficial tool in the

quest to sustainably feed the growing population


Scientists worldwide endorse GM as an important tool for breeding

“Both genetic improvementand better crop management

are vital and both should beresourced in parallel.” - 2009

“The ASPB believes strongly that, with continued responsible regulation and oversight, GE will bring many significant health and environmental benefits to the world and its people.” - 2006


GMOs in the newsRothamsted’s response to activists

Aphid alarm pheromone (E)-β-farnesene

At Rothamsted Research in England, wheat plants were engineered to produce a chemical alarm signal that deters aphids

Source: Rothamsted Research; Sense about Science.

Activists threatened to destroy the experimental plants

Rothamsted scientists and supporters responded with public appeal, video, debate and petition with more than 6000 signatures

Ultimately, no plants were destroyed and the experiment was completed successfully


GMOs in the newsAnti-GMO activist Lynas apologizes

In January 2013, Lynas apologized for his prior anti-GM activities, saying that he’d been “completely wrong to oppose GMOs”, and urging others to reconsider their opposition

Source: Mark Lynas

Mark Lynas is a well-known author and journalist

whose work has focused on the environmental

effects of climate change

“So my message to the anti-GM lobby … is this. You are entitled to your views. But you must know by now that they are not supported by science.”


10/17/2013



GMOs in the newsFalse claims about GMO threats

Daily Mail: “Uncovered, the 'toxic' gene hiding in GM crops: Revelation throws new doubt over safety of foods”

-(21 Jan 2013)

Reuters: “Monsanto corn study in France finds tumors and organ damage in rats”

-(19 Sept 2012)

Natural News: “GMOs may be the new thalidomide”-(19 Sept 2012)

Daily Mail: “Cancer row over GM foods as study says it did THIS to rats... and can cause organ damage and early death in humans”

-(19 Sept 2012)


Anti-GM activists intentionally propagate fear and misinformation

The more a technology is associated with “risk” in the media, the greater the public experiences it as “risky” – this is called “the social amplification of risk”

Sjoberg, L. (2004). Principles of risk perception applied to gene technology. EMBO Rep. 5: S47-S51. Frewer, L.J., Miles, S. and Marsh, R. (2002). The Media and Genetically Modified Foods: Evidence in Support of Social Amplification of Risk. Risk Analysis. 22: 701-711. Frewer, L. (2003). 10. Societal issues and public attitudes towards genetically modified foods. Trends in Food Science & Technology. 14: 319-332.


Example: A retracted study blaming vaccines for autism had a big impact

A since-retracted report that the MMR vaccine causes autism led to a dramatic decrease in children being vaccinated, leading to disease outbreaks and an increase in mortality from these diseases

Plotkin, S., Gerber, J.S. and Offit, P.A. (2009). Vaccines and Autism: A Tale of Shifting Hypotheses. Clinical Infectious Diseases. 48: 456-461; Data from Health Protection Scheme UK; Cottrell, S. and Roberts, R.J. (2011). Measles outbreak in Europe. BMJ. 342: d3724.

1996 2000 2005 2010

1500

1000

500

50000

10000

20000

30000

40000

Reported cases of measles and mumpsin England (1996 – 2010)

94

90

86

82

Percentage of children who completed their MMR vaccination course in England (1996 – 2010)

Wakefield et al., 1998


GMOs in the news “The Séralini affair”

Sept. 19, 2012 Gilles-Eric Séralini released a report that claimed rats fed GM corn died 2 – 3 times more than control rats

Sept.– Nov. 2012

The European Food Safety Authority

reports that Séralini’s study “does not meet acceptable scientific

standards”

European Food Safety Authority (2012) Final review of the Séralini et al. (2012a) publication on a 2-year rodent feeding study with glyphosate formulations and GM maize NK603 as published online on 19 September 2012 in Food and Chemical Toxicology EFSA Journal 2012;10(11):2986

Long term toxicity of a Roundup herbicide and a Roundup‐tolerantgenetically modified maizeSéralini, G.E., Clair,E., Mesnage, R., Gress, S., Defarge, N., Malatesta, M., Hennequin, D., and Spiroux de Vendômois, J.

Food Chem. Toxicol. 50: 4221–4231September 19, 2012

http://dx.doi.org/10.1016/j.fct.2012.08.005

Dozens of letters were written to the journal editor pointing out deficiencies in

the research


• Sample sizes too small to be statistically significant

• “Cherry picking”: only some data presented

• Inappropriate test organism

• A dubious non-disclosure agreement that prevented reporters from consulting other experts about the research

The Séralini affair: Major flaws in the study include:


Is a diet that contains Roundup or Roundup-tolerant corn toxic?

GM+R

GM

GM

R

Some rats had their diet supplemented with non-GM corn

Some rats had their diet supplemented with GM corn GM

Some rats had their diet supplemented with GM corn that had been sprayed with Roundup

Some rats had their diet supplemented with non-GM corn and had Roundup added to their water

To investigate toxicity, rats were given special diets for the duration of their lives (up to 680 days)

GM The proportion of corn in their diet is indicated by the size of the inner circle


Experimental design: 1 control, 9 treatments

33% of food from non-GM corn

11%, 22% or 33% of food from GM corn

CO

NT

RO

L

11%, 22% or 33% of food from GM cornsprayed in the field

with Roundup

33% of food from non-GM corn, and water supplemented with 0.1 –5 x106 ppb Roundup

0.1 ppb

9 x105

ppb5 x106

ppb

GMGMGM GM+R

GM+R

GM+R

(The maximum tolerance for Roundup in corn is 1 x 103 ppb) EPA


Experimental design: 10 male and 10 female rats in each group

♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀♂ ♀ ♂ ♀ ♂ ♀

0.1 ppb

9 x105

ppb5 x106

ppb

GMGMGM GM+R

GM+R

GM+R


Results: Survival at 600 (♂) or 680 (♀) days

♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀♂ ♀ ♂ ♀ ♂ ♀

0.1 ppb

9 x105

ppb5 x106

ppb

GMGMGMGM+R

GM+R

GM+R

What do these results indicate about toxicity of GM corn or Roundup?


10/17/2013



The mortality data show no statistically significant treatment effects

Panchin, A.Y. (2013). Toxicity of roundup-tolerant genetically modified maize is not supported by statistical tests. Food Chem. Toxicol, 53: 475; Schorsch, F. (2013). Serious inadequacies regarding the pathology data presented in the paper by Séralini et al. (2012). Food Chem. Toxicol. 53: 465 – 466.

7 heads3 tails

5 heads5 tails

4 heads6 tails

3 heads7 tails

2 heads8 tails

4 heads6 tails

5 heads5 tails

Different values do not indicate real and reproducible differences

For example, how does the color of the hat affect the outcome of the coin toss? Obviously, it has no effect; the different numbers are a result of random variation

When Séralini’s data were analyzed, no significant differences were found between control and treatment groups


“Cherry picking” means showing only a subset of data

Sanders, D., Kamoun, S., Williams, B. and Festing, M. (2013). Letter to the editor. Food and Chemical Toxicology. 53: 450-453; iPetitions.

It is unethical to exclude data that don’t fit the hypothesis

Hundreds of scientists have called on the authors to release their complete data set. The authors so far have refused to release the rest of the data

“All data cannot be shown in one report, and the most relevant are described here.”

-Séralini, 2012

Hiding conflicting data is also described as “sweeping it under the rug”


7 heads3 tails

2 heads8 tails

If only some data are shown, the inherent variability of the study is hidden and differences are exaggerated

“Cherry picking” data skews data interpretation

“Wearing a blue hat causes 3.5 more

‘heads’ than wearing a pink hat”

Is this interpretation justified?

Of course not


The authors show photos of tumors only on GM-fed rats

Look at the tumor on this rat that ate

GM corn!

Old Sprague-Dawley rats typically develop tumors no matter what they eat, and they did in the Séralini study, but showing a control rat with a tumor would dilute the association between GM and tumor formation


As a consequence, many journalists passed on the press release as legitimate news

Séralini’s paper was released with a non-

disclosure agreement, meaning no experts could be consulted

Séralini manipulated the press embargo

Many articles are released to the press under an embargo, which allows the journalists time to research their articles

This usually involves getting an opinion from an independent

expert


Scientists need to ensure that that debate, legislation and policy decisions are based on well-grounded

scientific evidence

“The majority of agricultural scientists, including myself, anticipate great benefits from biotechnology…

Genetic modification of crops is not some kind of witchcraft; rather, it is the progressive harnessing of the forces of nature to the benefit of feeding the human race…

We must be on guard against politically opportunistic, pseudo-scientists…

-Norman Borlaug, Nobel Laureate

Sanders, D., Kamoun, S., Williams, B. and Festing, M. (2013). Letter to the editor. Food and Chemical Toxicology. 53: 450-453; Borlaug, N.E. (2000). Ending World Hunger. The Promise of Biotechnology and the Threat of Antiscience Zealotry. Plant Physiol. 124: 487-490.

Most scientists support the continuing assessment of all new crops, including those developed by GM tools, and support informed public debate about their use

Documents

10/17/2013 The American Society of Plant Biologists · The Plant Cell, October 2013 © 2013 The American Society of Plant Biologists 10/17/2013 3