Plants are the oldest and largest things on the planet and supply the oxygen to sustain life. Besides being a link in the food chain, plants also have a remarkable range of other uses; medicinal and healing, cosmetics and fragrance, relaxation and aromatherapy, dyeing and insect repellents, as well as providing a valuable construction commodity.
Increasingly, they will be used to benefit human health by making pharmaceuticals or other products for the healthcare industry.
Many tropical plants contain enzymes with unusual medical applications. One example is pineapple juice - its use as a meat-tenderiser led to a component being used to digest human skin before skin grafts. Biotechnology can produce large, pure quantities of this "flesh-eating" enzyme in a plant from which it is more readily extractable. The enzyme can also be modified to perform better at the pH of the human body and could be used in treating gangrene.
Plants have provided some of the most important drugs used in medicine such as aspirin and morphine.
Today, 25% of all prescription drugs are derived from plants and, although largely unlicensed in the UK, herbal remedies are a popular alternative. They have been used by the Chinese for at least 4,000 years, by the ancient Greeks for the treatment of gout and were frequently associated with witchcraft in the middle ages.
Even nature's poisons have both medicinal and cosmetic roles, as well as occasionally being used in suspicious circumstances.
Deadly nightshade, or belladonna, was a favourite among women in medieval Italy as it dilated the pupils of their eyes making them "sparkly and dreamy". Until recently it was used in ophthalmology and carried by soldiers as an antidote to nerve gas attack.
Digitalis purpurea, or foxglove, combines beauty with a lethal toxicity and many of its common names recall its deadly nature: witch's glove and dead man's bells. A drug derived from foxglove, digitonin, is now used to treat heart ailments. However, the therapeutic dose is dangerously close to the lethal dose.
Fruits and vegetables contain a variety of essential minerals, vitamins and other beneficial compounds such as anti-oxidants which have anti-cancer properties. Even common garden weeds such as dandelions and clover, are a source of anti-viral, anti-bacterial and anti-inflammatory agents.
Plants are natural and clean biorefineries and their wealth of products provide many potential opportunities for the biotechnology industry. Since the dawn of agricultural practices 10 to 12 millennia ago, farmers have constantly tried to get the best yield from their crops. Biotechnology can be thought of as an evolution of traditional agricultural methods and can be used to overcome factors like drought, pests, weeds and wind which normally adversely affect plant productivity.
Conventional plant breeding involves the crossing of plants and "shuffling of genes" over many generations to improve certain qualities. However, while obtaining beneficial traits, toxins or allergenic proteins may be an unwanted side-effect that creeps in.
Genetic modification, on the other hand is an efficient way of precisely enhancing a specific quality. By combining modern technology with old practices, farmers will be able to produce crops more efficiently and cost effectively.
Plants have been genetically modified to produce drugs and edible vaccines. Vaccines in vegetables and fruit are being developed to reduce infant death from hepatitis, cholera or diarrhoeal disease in developing countries. Bananas are inexpensive to produce and can be eaten raw, they are native to many developing countries and are one of the first foods eaten by infants. Packaged inside the banana, the vaccine is easy to store and distribute without the need for refrigeration. Perhaps a banana a day will keep the doctor away.
Certain crops which are highly susceptible to plant viruses, such as melons, squash and cucumbers, can be given a genetic vaccine to help reduce the spread of crop disease and the need for chemical sprays.
Many foodstuffs contain allergens. Peanuts cause a severe and often fatal allergic response in some people. Rice is a major food in Asia but there is a high rate of rice allergy in the population. But biotechnologists have identified the part of the allergenic proteins causing the problem, allowing the creation of allergen-free products.
Some species of aquatic plants like duckweed naturally mop up heavy metal contaminants from their watery habitats. Furthermore, these tiny plants are able to convert the metal from a toxic to a more benign form. Plants can also be genetically engineered for bioremediation to take up pollutants and break them down into less hazardous by-products.
Worldwide, large amounts of soil and groundwater are contaminated with organic pollutants, such as the areas around ammunition production, processing and test-sites. As many of these compounds are toxic, this poses a significant potential health risk to humans and wildlife.
Dr Neil Bruce's group at the Institute of Biotechnology in Cambridge has engineered transgenic plants to produce a microbial enzyme that completely degrades explosives such as TNT into harmless compounds. This technique - phytoremediation - is becoming a reality.
Plants are highly adaptable to their environment and have evolved to survive extreme environments such as the desert. They can be genetically modified to withstand low-temperatures and flooding or to be more tolerant to salt and metals in the earth.
These improvements allow crops to be grown in areas where previously they could not survive. With increasing world population and loss of suitable land for farming this is a hugely beneficial application of biotechnology.
With the global population set to reach more than 8 billion people by 2050, plant biotechnology could help to alleviate hunger world-wide through the development of crop varieties with increased yields and requiring fewer fertilisers, herbicides and pesticides.
Their contribution to the development of new drugs for human and animal health is of huge importance, particularly with the rise of the antibiotic-resistant superbugs. Plants are our green gold and have the potential to be the biofactories of the future. Surely this is food for thought.
Dr Claire Cockcroft is a molecular biologist at the Institute of Biotechnology in Cambridge.
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