How to Feed a Hungry World World Population

How to Feed a Hungry World

World Population Levels • 6 billion in 1999 • Will probably reach 8 billion by 2020, this will add 2 billion in 20 years • A population of 8 billion will present major problems in the production and distribution of sufficient food

Status of Hunger • Approximately 1 billion people not getting sufficient food today • Marasmus and Kwashiorkor are common in developing nations • How can we adequately feed the anticipated 2 billion that will be added to the population?

Improvements in Agriculture • Improvements in crop yields began early in 20 th century - as Mendel’s work became known • In past 50 yrs US yields continued to increase - 3 fold increase since 1940 s – 1940 s - corn yields 40 bushels/acre – 1990 s - corn yields 200 bushels/acre • High yielding varieties at the center of this accomplishment -- BUT not alone

High Yield Crops • Also known as high impact crops and high responding crops • High Impact Crops Require – Excellent growing conditions – Mechanization – Fertilizers --- may be the most important – Pesticides – Irrigation

Green Revolution • After WWII, Rockefeller Foundation and other agencies set up Agricultural Research Stations in tropical areas • Goal - improve crop production in developing nations like those in US • Most research initially focused on wheat, rice, and corn but potatoes and cassava research added later

Wheat - Principal Focus of Green Revolution • Father of Green Revolution - Dr. Norman Borlaug – Developed high yielding dwarf varieties that take heavy fertilizer without lodging – By late 1960 s food production dramatically increased in many developing nations – 1970 - Borlaug awarded Nobel Peace Prize “abolish hunger in a few years”

Disease and Pest Resistance • Another aim of the Green Revolution • 50% of the world’s crops destroyed in field or in storage due to fungi, bacteria, viruses, nematodes and insects – Insects are chief competitors for human food – Fungi right behind

Ways to Produce Healthy Plants • Chemicals • Biological Controls • Disease-Resistant Crops - cheapest and most effective method – Breeding for disease resistance must be coupled to yield, quality, climate, taste • Integrated Pest Management (IPM)

Problems with the Green Revolution: What went wrong? • Optimism of the 60 s gave way to the realities of 70 s – Cost associated with seeds, fertilizer, pesticides, irrigation, farm equipment, fuel – High energy costs - 2 barrels of oil/barrel of fertilizer – Environmental damage – Loss of genetic diversity – Whole premise wrong

Loss of Genetic Diversity • Modern agriculture based on monocultures - disadvantages • Share vulnerability to disease • Loss of genetic diversity • Native varieties are being replaced • Tropical forests being cleared • Will we have the resources to continue developing new varieties? • Seed banks may help but who owns the genes?

Solutions • Continue along present course - some researchers believe that we are near the maximum potential yields for many crops • Alternative crops • Biotechnology

Biotechnology • Use of living organisms to provide products for humanity • Today term often implies the use of genetic engineering to create plants with new and useful characteristics • Intent no different that traditional plant breeding - differs in methods, speed, and possible crosses

Cell and Tissue Culture • Plant cells can be cultured to get an undifferentiated mass of cells called a callus • When the right % of hormones are added to the culture, the callus will develop into a plant

Mutations in Cell Cultures • Although all cells in culture are clones, sometimes mutations occur • During sexual reproduction, mutations are rare - maybe 1 in 1 million • In tissue culture mutation rate much greater - called somaclonal mutants • In one experiment with tomato plants from culture 13 mutations in 230 plants

Applications of Cell Culture • Somaclonal mutants may have useful traits • Expose tissue culture to certain toxins or poisons to find resistant plants – parasite toxins to look for resistance – herbicides to look for resistance

Genetic Engineering • Genetic Engineering uses the techniques of recombinant DNA to produce transgenic plants – Recombinant DNA transfers segments of DNA from one organisms to another – Plants with foreign genes are called transgenic plants – This is possible because all organism use the same genetic code

Gene Function

Gene Transfer • • • Identify gene of interest Select a vector for transferring the gene Cut the gene from donor organism Transfer gene to vector Insert into host organism

Plasmids Used to Transfer Gene

Success of Genetic Engineering • First successful genetically engineered experiment on a plant in 1982 • First crop approved for sale in 1994 - Flavr. Savr tomato • Today dozens of genetically engineered crops on the market • Thousand of field tests

Genetically Engineered Plants • Herbicide-resistant soybean, cotton, corn, and canola • Insect-resistant corn, cotton, potato have genes for Bt (Bacillus thuringiensis) toxins • Tomatoes with delayed ripening • Canola with high lauric acid production

Checks • Lots of approval required before the crops are released in environment • Federal agency approving crops for marketing – FDA – EPA – USDA

Environmental Concerns • Can the organism pass on traits in the environment? – Can herbicide resistance spread to weeds? • Can insects become resistant to Bt toxins? • Can harmful traits be passed on accidentally? Brazil nut allergen in soy