Briefly describe the applications of rDNA technology in crop improvement.
Recombinant DNA technology has revolutionized crop improvement with several significant applications.
The major goal of plant transgenics has been to increase the yield of crops and also to improve the nutritional quality of crop products to cater to the needs of the ever-increasing human population.
Transgenic crops have been generated for tolerance to herbicides and resistance to biotic stress caused by pathogens like bacteria, fungi, viruses, insects, and nematodes. These traits result in significant enhancement in crop productivity by reducing losses due to diseases and pests.
rDNA technology has enabled the development of crops with tolerance to abiotic stress factors like drought, salinity, and extreme temperatures. Abiotic stress response involves the production of stress-related osmolytes like sugars (trehalose, fructans), amino acids (betaine, proline), and certain proteins that help plants perform better in harsh environmental conditions.
Strategies for increasing crop yield also include modifying the photosynthetic machinery, manipulating enzyme activity, increasing sugar to starch conversion, and improving nutritional quality. A notable example is Golden Rice, which has increased expression of vitamin A. Other applications include delayed fruit ripening and enhanced nutrient quality. Many traits have been commercialized, while others are being tested in field conditions.
Explanation
This answer is based on the textbook context which discusses applications of transgenic plants in agriculture. The key points covered include: increasing yield and nutritional quality, resistance to biotic stress (pathogens), tolerance to abiotic stress (environmental factors), specific examples like Golden Rice, and various strategies like modifying photosynthetic machinery. The answer follows the 5-mark format with 5 paragraphs and uses bold terms for key concepts.