Biotechnological Application in Agriculture

• Biotechnology in agriculture is used to increase yield, improve crop quality, reduce losses, and decrease dependence on chemicals.
• Three approaches to increase food production are agrochemical-based agriculture, organic agriculture, and genetically engineered crop-based agriculture.

• Tissue culture is the growth of plant cells, tissues, or organs on a sterile nutrient medium.
• Totipotency is the ability of a plant cell or explant to develop into a complete plant.
• Nutrient medium must contain sucrose, inorganic salts, vitamins, amino acids, and growth regulators such as auxins and cytokinins.
• Micropropagation is the production of thousands of plants in a short time through tissue culture.
• Plants produced by micropropagation are genetically identical to the parent plant and are called somaclones.
• Examples: tomato, banana, apple, sugarcane, and potato.

• Meristem culture is used to obtain virus-free plants.
• Even if a plant is infected, the apical and axillary meristems are usually virus-free.
• Meristems of banana, sugarcane, and potato have been cultured successfully.

Scientists isolate single cells and remove their cell walls to obtain protoplasts. Protoplasts from two different plant varieties can be fused to form a hybrid protoplast. This process is called somatic hybridisation.

• Example: fusion of tomato and potato protoplasts produced pomato.
• Pomato was produced experimentally but was not useful commercially.

Genetically Modified Organisms (GMOs) are plants, bacteria, fungi, or animals whose genes have been altered by manipulation.

GM plants are useful because they:

• tolerate abiotic stresses such as cold, drought, salt, and heat.
• reduce dependence on chemical pesticides.
• reduce post-harvest losses.
• increase efficiency of mineral usage.
• improve nutritional value of food.

Example: golden rice is enriched with vitamin A.

• Bt toxin is produced by the bacterium Bacillus thuringiensis.
• Bt gene has been introduced into crops to provide resistance against insect pests.
• Examples of Bt crops include cotton, corn, rice, tomato, potato, and soybean.
• In Bacillus thuringiensis, the toxin exists as an inactive protoxin.
• When an insect ingests it, alkaline pH in the insect gut activates the toxin.
• The activated toxin binds to midgut epithelial cells, forms pores, causes cell lysis, and kills the insect.
• Gene cryIAc and cryIIAb control cotton bollworms, while cryIAb controls corn borer.

• The nematode Meloidogyne incognita infects tobacco roots and reduces yield.
• Protection against this pest was developed using RNA interference (RNAi).
• RNAi is a cellular defence mechanism in eukaryotes that silences specific mRNA using complementary double-stranded RNA.
• Nematode-specific genes were introduced into the host plant using Agrobacterium vectors.
• The host plant produced both sense and antisense RNA, which formed dsRNA.
• dsRNA triggered RNAi and silenced the nematode’s specific mRNA.
• As a result, the parasite could not survive in the transgenic plant.

• Totipotency is the basis of tissue culture.
• Micropropagation produces many plants rapidly.
• Somaclones are plants obtained through tissue culture.
• Meristem culture helps produce virus-free plants.
• Somatic hybridisation involves the fusion of protoplasts.
• Golden rice is an example of a nutritionally improved GM crop.
• Bt cotton protects against bollworms.
• Bt protoxin becomes active in the alkaline gut of insects.
• RNAi silences specific mRNA and helps control pests like Meloidogyne incognita.