Crops, biofuels, food and the environment

Better crops. Scientists mainly improve crops for five traits: insect resistance, herbicide resistance, virus resistance, delayed ripening and better nutrition. Plants carrying genes added in the lab are genetically modified organisms (GMOs).

• Virus-resistant plants carry a gene for the virus's own coat protein, which protects them.
• Bt cotton carries a toxin gene from the bacterium Bacillus thuringiensis. The plant makes the toxin itself, which kills bollworms, so farmers spray less pesticide.
• Roundup-ready soybean tolerates the weedkiller glyphosate, so weeds can be sprayed without harming the crop.
• Flavr Savr tomato ripens slowly, so it stays fresh longer.
• Golden Rice is rich in beta-carotene, which the body turns into vitamin A.
• Chilling-tolerant tobacco survives cold.

Plant tissue culture grows plant cells or pieces in a nutrient medium. It gives many exact copies (true-to-type plants), haploid plants from anthers, and a way to store plant varieties (germplasm). Transgenic plants can also make medicines: antibiotics for animal feed, and edible vaccines in potato, which are under trial.

Biofuels are fuels made from plant or animal material (biomass): bioethanol from sugars and starch, bio-butanol, biodiesel from oils and fats (for example from Jatropha and rapeseed), and biogas. Sweet sorghum needs little water, so it suits dry lands.

The environment. Living things can act as warning signals. In biosensors, a microbe is engineered to respond to a pollutant: E. coli carrying the lux gene gives off light when mercury is present. In bioremediation, organisms clean up pollution: the enzyme biphenyl dioxygenase breaks down the toxic chemical PCB. Hyper-accumulator plants soak up heavy metals like cadmium, mercury and lead from polluted soil.