Biotechnology and Crop Improvement

Plant biotechnology, a major component of agricultural biotechnology, deals with various aspects of plant tissue culture, genetic transformation, and molecular biology techniques. Tissue culture methods offer a rich scope for creation, conservation, and utilization of genetic variability for the improvement of field, fruit, vegetable, and forest crops, and medicinal/aromatic plants. Micropropagation technology ensures true to type, rapid and mass multiplication of plants that possesses special significance in vegetatively propagated plant species. This technology has witnessed a huge expansion globally, with an estimated global market of 15 billion US$/annum for tissue-culture products. Some basic techniques of tissue culture, such as anther/microspore culture, somaclonal variation, embryo culture, and somatic hybridization, are being exploited to generate useful genetic variability for obtaining incremental improvement in commercial cultivars. Production of secondary metabolites, such as food flavors, food colors, dyes, perfumes, drugs, and scented oils used in aromatherapy, through cell cultures and hairy root cultures, are leading examples of molecular farming. Cryopreservation of germplasm at the cell/tissue/organ levels, in liquid nitrogen at -196 degrees C, is highly rewarding for establishing germplasm banks, especially for vegetatively propagated crops and rare, endangered plant species. During the past 15 years, remarkable achievements have been made in the production, characterization, field evaluation, and release of transgenic varieties/hybrids in several crops. Transgenic varieties/hybrids of maize, cotton, soybean, potato, tomato, and papaya are now being commercially grown on about 134 million hectares spread across 25 countries. Research in genomics allows high-resolution genetic analysis for physical mapping and positional gene cloning of useful genes for crop improvement. Molecular (DNA) markers help in precise characterization of germplasm, construction of saturated linkage maps, and DNA fingerprinting of crop varieties. Molecular markers are now increasingly being used for marker-assisted gene pyramiding and alien gene introgression. Current research, involving large-scale DNA sequencing, microarrays, and robotics, is heading towards gene revolution and nanobiotechnology.