MadSci Network: Agricultural Sciences |
Whenever you are dealing with living organisms, genetics is of central importance. Farmers and nurserymen also need to be concerned about genetics of insect pests and disease organisms. Animal farmers have created problems by overuse of antibiotics, which leads to antibiotic resistant bacterial strains. Plant breeding has long been important to increases in crop yield and development of new and better cultivated varieties (cultivars) of food and ornamental plants. More recently, genetic engineering has become widespread in food crops and may become more important in farm animals. Cornell University estimates that about 60 to 70% of processed foods in U.S. supermarkets contain genetically engineered crops, mainly from genetically engineered corn, soybeans, canola and cotton. Canola and cottonseed oils are used in many products. Outside the U.S., use of genetic engineered crops have often been banned. Genetic engineering has a lot of potential to improve both food and ornamental plants. There is interest in trying to introduce apomixis and parthenocarpy genes into more crops. Apomixis is the production of asexual seeds. Parthenocarpy is production of fruits without pollination and fertiliation. Parthenocarpic fruits are seedless. Other improvements possible with genetic engineering include crops with resistance to diseases, insects and herbicides, crops with higher vitamin content and new flower colors such as blue carnations, blue roses and blue chrysanthemums. More traditional breeding has resulted in many new cultivars. Seedless grapes have become much more available because of many new cultivars. Breeding of several of these new seedless grape cultivars used a tissue culture technique, known as embryo rescue. Plant farmers have similar problems with pesticide use resulting in pesticide resistant insects and diseases. Grain and vegetable producers use new cultivars as one method to deal with diseases, insects and increase yield. Fruit tree growers often use cultivars that are a century or more old so depend less on breeding. For example, 'Granny Smith' apple is a relatively new cultivar in the U.S. but originated in the mid-1800s. A major problem in plant agriculture is lack of genetic diversity in crops grown. The second website indicates there are over 17,000 known apple cultivars but most supermarkets offer fewer than a dozen kinds. Animal farmers often use artificial insemination for farm animals including cattle, sheep, goats and horses. It is a breeding technique to select the male parent with the best genes. Embryo transfer is also used in breeding of some farm animals. It implants eggs from female animals with superior genes in the wombs of other animals. Dolly the sheep brought a lot of attention to the possibility of cloning farm animals. However, there are technical problems that have to be overcome before cloning of farm animals becomes a commercial process. Cloning is very widely used in plant agriculture. Most fruit and nut crops are cloned by grafting. Most nursery plants are cloned by grafting or rooting of cuttings. Cuttings also used for many greenhouse flowers such as chrysanthemum, poinsettia and carnation. Tissue culture propagation is used to clone many greenhouse plants, such as many houseplants and orchids. References GE Foods in the Market “A” is for antique apples Glimpses into sexual plant reproduction: the pursuit of apomixis The quest to create the blue rose New Summer Seedless Black Grape Developed Animal Genetics Artificial Insemination Dolly the sheep clone dies young Re: What are some good things and bad things about plant cloning?
Try the links in the MadSci Library for more information on Agricultural Sciences.