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The History of Plant Breeding–Improving on Nature? – Agweb Powered by Farm Journal

Posted: November 28, 2020 at 11:56 am

The existence of human life on this planet relies entirely on a biochemical process called photosynthesis, which enables green plants to convert sunlight, water, and carbon dioxide into chemical energy in the form of carbohydrates and plant proteins, which humans and and other animals consume in order to sustain their lives. Even among peoples who rely almost entirely on animal foods in their diets due to the extreme climates they live in, such as the Inuit (Eskimo) tribes in Alaska, who live on seal, walrus, and whale meat, survive because those mammals consume small fish, which in turn feed on plankton, algae, and other fish and their eggs. Without plants, there would be no life on this planet.

As I described in a blog in March of 2019, humans are believed to have raised the first domesticated plant species called emmer, an ancestor of modern wheat and barley varieties, about 10,000 years ago in the Middle East. Squash was the first crop domesticated in the Western hemisphere, in ancient Mexico, during the same period. Maize (corn) followed about 2,000 years later, also in meso-America, and rice was first cultivated in the Indus valley in Asia about 4,500 years ago. The youngest of the major food crops which dominate consumption and trade worldwide is soybeans, which was first cultivated in north China more than 3,000 years ago. Combined, corn, wheat, and rice account for about 60 percent of all calories and protein obtained by humans from plants.

When humans migrated across the globe in search of new places to live, they took their staple crops with them, but some of them also found and eventually adopted other crops being raised by the native populations, some of which over time became staple crops to them. As I described in my recently published book on the history of U.S. agricultural policy (co-authored with Dr. Steve Halbrook), many of the new arrivals from Great Britain who had farmed previously, especially those settling in the colonies in the middle Atlantic area such as Pennsylvania and Maryland, insisted on cultivating food crops they were familiar with, such as wheat, rye, and barley. In the northern colonies such as Massachusetts, where most of the new arrivals had not farmed previously, they adopted the crops their native neighbors had farmed for millennia--beans, squash, pumpkins, and maize (corn), using those crops in 3-5 year rotations. In the southern colonies, two of the most important crops were not produced for food--tobacco and cotton, both of which were first grown in the Jamestown settlement in Virginia in the 1610s with seeds brought from Caribbean islands.

While throughout history, farmers have sought to identify and preserve good performing seeds for their crops, the first scientifically based crop breeding work did not occur until after the groundbreaking work of Gregor Mendel in the middle of the 19th century. Mendel was an Austrian monk who demonstrated the rules of heredity by systematically cross-breeding pea plants and studying the traits which appeared in the offspring plants. However, the full significance of Mendel's work was not recognized until nearly the turn of the 20th century (more than three decades later) with the rediscovery and application of his laws to commercial plant breeding efforts. John Garton, an English agriculturalist, was one of the first to cross-pollinate agricultural plants and commercialize the newly created varieties. He began experimenting with the artificial cross pollination initially of cereal plants in the 1890s, then branched out to herbage species and root crops and developed far reaching techniques in plant breeding

The next major breakthrough came with the shuttle breeding approach developed by Dr. Norman Borlaug in his work on wheat at the institute that eventually became CIMMYT (International Wheat and Maize Research) outside of Mexico City, starting in the late 1940s. Working in a mild climate that allowed for multiple crops in a year in different growing conditions, he was able to relatively quickly identify and refine traits that led to high-yielding, disease resistant varieties of wheat that were eventually adopted in many parts of the world. This work earned him the Nobel Peace Prize in 1970, for for having given a well-founded hope - the green revolution.

The emergence of genetic engineering techniques led to the first genetically modified organisms (GMO's) to be developed and released for commercial use in the mid-1990s. The first wave of such crops, mainly utilizing popular row crops such as corn, soybeans, and cotton, to add new traits such as insect resistance and pesticide resistance through the insertion of genetic material from other organisms, most commonly the bacillus thuringiensis (BT) bacterium. More recently, new techniques have been developed to enable editing DNA segments of individual crops themselves, by turning on or shutting off certain genes that already exist within specific organisms. These techniques, known as CRISPR or CAS9, recently won recognition through the awarding of the 2020 Nobel Prize for chemistry to their developers, Dr. Emmanuelle Charpentier from the Max Planck institute in Germany and Dr. Jennifer Doudna from U.C.-Berkeley.

For the last decade or so, plant scientists around the world have been working on ways to improve the photosynthetic process itself, by improving the efficiency with which plants convert water, sunlight, and carbon dioxide into plant growth. Much of that work is taking place through the RIPE project (Realizing Increased Photosynthetic Efficiency) headquartered at the University of Illinois, funded primarily by the Bill and Melinda Gates Foundation, the Foundation for Food and Agriculture Research (FFAR), and the U.K.s Foreign Commonwealth and Development Office (formerly the Department for International Development, or DFID). In research published in 2019, efforts to engineer alternate pathways to refine the photosynthesis process were found to drastically shorten the trip and save enough resources to boost plant growth by 40 percent. This is the first time that an engineered photorespiration fix has been tested in real-world agronomic conditions. Other work is underway at a consortium of universities to develop rice varieties that use the more efficient C4 photosynthesis pathway such as is found in corn and sugarcane, eschewing the less efficient C3 pathway that rice plants currently utilize. A November 2020 article described their current work, which involved assembling five genes from maize that code for five enzymes in the C4 photosynthetic pathway into a single gene construct and installing it into rice plants.

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The History of Plant Breeding--Improving on Nature? - Agweb Powered by Farm Journal

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