Overview of Crop Improvement Approaches

During the past 100 years, crop improvement came to rely more and more on biology and laboratory

methods.

In developed countries, research is done by companies that sell seeds. Developing countries

rely on the International Research Institutes but their resources are limited.

Where were our crops domesticated

Mesoamerica: corn, common bean, squash, sweet potato, tomato, upland cottonAndean region: potato, common bean, peppers, cassava, pineapple, pima cottonAfrican Sahel + Ethiopia: sorghum, African rice, coffee, okra, melon, cowpeaNear East: wheat, barley, pea, lentil, chickpea, grape, Eastern India and South-East Asia: mungbean, cucumber, banana and plantain, eggplant, coconut, teaSouthern China: Asian rice, soybean, citrus, tea, cabbage

Land racesRelative reproductive isolation and

differing conditions of soil, nutrients, diseases, insects, water, day length etc created numerous

landraces of our crops. Landraces do not have a fixed complement of

genes (alleles) because subsistence farmers are always trading seeds and the conditions change over time (hundreds of

years). All land races of one species have the same genes

(unless deletions occurred), but many different alleles =

biodiversityCorn from different fields

The rise of agricultural experiment and plant breeding stations in the 19th Century

Established in 1843, Rothamsted it is the oldest agricultural experiment station in continuous existence. The Broadbalk wheat experiment has

different crop rotations, levels of fertilizer etc and yields have been measured for 160 years. Analogous fields in the US are the Morrow Plots

at the University of Illinois, established in 1876.

Lower right: Remote sensing of crop growth on the Morrow Plots. Intensities reflect the

level of plant growth/fertilizer application

University of IllinoisRothamsted Expt. Sta.

The March of Genetic Technology

1860 Mendel: making crosses, introducing genes

1920 Discovery of hybrid vigor

1950 Inducing mutations

1960 Tissue culture and embryo rescue

1980 Plant transformation and GM crops

2000 Genomics (study of all the genes)

Gregor Mendel

Lycopersiconesculentum

Lycopersiconperuvianum

Back-crossseries

Tomato Cultivar with new trait

INTER-SPECIFIC CROSS or INTRA-SPECIFIC CROSS THAT IS NORMALLY FERTILE

# 1 Introgression of a specific trait

# 2 Hybridization: To produce a hybrid strain one starts with two “inbreds” (strains that have been self-fertilized for several

generations) and then crosses these inbreds. The seeds resulting from this cross are sold to the farmers. They will produce bigger plants with larger ears. However, when the

seeds of these ears are planted again the “hybrid vigor” is lost. We do not yet understand the genetic basis of hybrid vigor.

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Inbred Hybrid Inbred

Maize is a monoecious plant with

separate male and female flowers.

This makes it much easier to produce

hybrids because it is easy to emaculate the

plants (remove the pollen producing

tassels) and control pollination

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Tassel =Male flowerProduces pollen

Silks = Female flowerBecomes the ear

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Hybrid rice, the result of controlled crossing of two varieties, is raising rice productivity in Asia and elsewhere.

Farmers cannot get the yield advantage is they save seed to replant,so the distribution of hybrid seeds is dependent on seed companies.In Africa most farmers are still too poor to buy the hybrid seeds.

# 3 Interspecific hybrids with embryo rescueTriticale, a new “synthetic” cereal,

is a cross between wheat and rye produced by embryo rescue of the product of fertilization and a chemically induced

chromosome doubling with cochicine

Wheat, triticale and ryeTriticale is now grown all over the world

Institute of Radiation BreedingIbaraki-ken, JAPAN

100m radius

89 TBqCobalt-60 source at the center

Shielding berm is 24

ft high

# 4Radiation breeding

Hundreds of crop varieties have been producedby radiation breeding. Plants or seeds are irradiated with gamma rays and their progenyexamined for agronomically useful traits.This is followed by extensive backcrossing.

-Radiation Field

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# 5 Genetic engineering of plants (creation of GMOs) relies on a natural gene transfer mechanism by

Agrobacterium tumefaciens from its Ti plasmid to the plant genomic DNA.

Discovered by Marc Van Montagu and Jeff Schell in Belgium and by Mary Dell Chilton and Eugene Nester in the USA

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http://www.ejbiotechnology.info/content/vol1/issue3/full/1/bip/

Genome SequencingImportant genes identified in one species (Arabidopsis or rice)can immediately be recognized in other species. All this information is public.Expression ProfilingDetermine the expression of thousands of genes at once on a “chip”Proteomics

# 6 Genomics, the most recent genetic technology

Where is plant breeding research done and who does it?

Developed countries1. Large agricultural biotech companies sell seeds and do research aimed at crop

improvement through genetic engineering and traditional breeding (Pioneer, Dupont, Monsanto, Bayer). They aim at the crops with big markets (corn, soybeans, potatoes,

wheat, cotton). They own many plant breeding sites.

2. Smaller seed companies produce hybrid vegetable seeds.

3. Universities and public institutions (USDA) do much less plant breeding than before, but do all the genomics research and gene discovery.

4. Small biotech companies (Mendel, Ceres etc) do gene discovery research.

Where is plant breeding done and who does it?Developing countries

1. Public domain breeding stations (NARS)2. C.G.I.A.R. Research Centers

CIMMYTMexico

IRRIPhilippines

The Consultative Group on International Agricultural Research has research centers all over the developing world and employs 8500 scientists and staff, with a $ 340 million annual budget that has to come from “donors”. The centers work with local plant agricultural institutions to improve crops and agric. practices.

Traditionally, CGIAR centers worked on major crops (rice, wheat, corn) but now they work with National Agricultural

Research Systems (NARS) and other stakeholders to release improved varieties of minor crops.

Newer is better-sorghum grain yields in 20 on-farm trails in Tanzania, 1994/95, show progressive improvements from "first generation" to "second generation" improved varieties

New pearl millet varieties consistently outperform traditional varieties in on-farm trials in Malawi and Tanzania

Pearl millet in MalawiSorghum in Tanzania

Increase in crop yields in different countriesSteady increases in the US started in 1930s with wheat breeding and

corn hybridization. Faster yield rise in India are due to double cropping.Genetics is key to raising yields in the world. Other inputs (fertilizers,

pest control, irrigation) are also needed

1. Agro-ecological system2. Resilience/fragility of the environment3. Ability to purchase inputs4. Reliability of seed distribution system5. Food preferences 6. Local food distribution system7. Export market

Genetics, a powerful tool to raise productivity, but must go hand in hand

with:

Average annual increase in yields of rice, wheat and maize in developing countries by periods.

(Nature 402, C55 - C58 (1999); Feeding the world in the twenty-first century. Gordon Conway and Gary Toenniessen)

Costs and benefits of agricultural research

Agricultural Productivity Increases

Benefits

• Improved per capita production

• Reduced unit costs and prices

• Increased incomes and purchasing power for farmers and consumers

• Restrained expansion into forests, grasslands, and wildlife habitats, helping to avert natural resource degradation

Costs• Increased soil salinity

and lowered water tables in irrigated areas

• Exacerbated health and environmental problems through inappropriate use of fertilizer and pesticides

• Displaced tenant farmers may not find employment.

New Research Agenda in the

Developing World

Production is de-emphasized.More responsive to consumer demand (organic agriculture)More emphasis on “functional foods”.More emphasis on precision farming technology. Developed technologies may not be accessible because of intellectual property rights (IPR).Higher proportion of research in biotech companies that emphasize technologies applicable at home.Smaller growth in funding than 20-30 years ago.

ImplicationsPardey, Alston and Pigott,

Intl. Food Policy Institute (IFPRI)

1. Less spillover; technologies being developed may not be appropriate for developing countries.

2. Applicable technologies may not be accessible because of intelectual property rights (patents)

3. When appropriate and accessible, technologies will require more development locally and require more sophisticated scientists.