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Since man first started raising crops, we have quested for stable varieties with high yield, no matter what the conditions may be. Our early ancestors developed many techniques such as cross breeding to develop some of our earliest crops. Humans have been seeking out plants that produced high yield fruit and grains, and nurturing specific varieties through selective breeding, until we developed the very crops we know today. Corn was once a small plant, which is today considered a weed, teosinte. Teosinte had very few grains on each fruiting body, and all grains had very hard outer seed cases that would protect the nutrition to be found inside. Through humans selecting varieties from the wild and cross breeding them by hand, we developed the many maize varieties we have built our civilization on. Today, we face an ever increasing challenge of producing more and more food for a growing human population. We must go back to our roots and continue to develop varieties, just as our ancestors before us, to meet this demand. Through the expanded biological understandings of genetics and new techniques of genetic modification we have to create varieties that increase yield, decrease herbicide and pesticide use, and ultimately grow more food. In this exercise students will learn more about the origins of plant varieties, and how we continue to develop new varieties by utilizing new technologies.
Science
Ag Competencies: 018.Agriscience in Our World
• Paper Plasmid Cloning (pg. S1-S5)
(30-45 minutes)
Classroom Discussion Introduce the topic and assess students for prior understanding. Let students discuss their ideas, and guide the discussion without telling them if they are right or wrong.
Potential Crossover Points
Explain to the class that domestication of plants and animals has always been about trying to meet the needs of humans based on our available resources. This is how civilization as we know it developed. We have used domestication methods of breeding and hybridization in the past with great success. Now we are growing our population more and more, so the demand for food is larger. These traditional methods of breeding are no longer able to provide the large amount of food needed to support our civilization. However, biotechnology allows us to do the same things we did with traditional breeding techniques, with higher success rates and more direct trait selection.
(45-60 minutes)
Background Information What is a plasmid? A plasmid is a small circular piece of DNA, which is often passed between bacteria. This allows genetic traits to move from one bacteria to another. A great example of this is the growing number of bacterial infections that are developing antibiotic resistance. The DNA that codes for this antibiotic resistance can sometimes be found on plasmids; once this plasmid has been developed it is passed from bacteria to bacteria taking with it the ability to resist certain antibiotics. The plasmid DNA is incorporated into the new bacterial DNA and all of the future offspring of that one bacteria (which is an asexual producing organism) now possess the gene for this antibiotic resistance. Scientists have used these plasmids to intentionally transmit genes that code for specific traits from one host organism, where the advantageous genes have been found, into a new organism (this process is called “transformation”). This new organism is now transgenic. Transgenic organisms have genes from the new host organism and their own genes. This process has been a great tool for humanity. We have used it to create crops that contain genes that will protect themselves from pest, resist herbicides, and survive in areas where the environment is not hospitable to traditional crop varieties.
The process of making plasmids involves multiple steps:
You then have to introduce the plasmid into the crop’s DNA and carefully select the cells where the new gene has been successfully inserted into the genome. This step can be difficult to do, because of this most scientist also include marker genes into their plasmid that allows scientists to easily determine if the transformation process occurred in the cells. One such marker gene will cause bacterial cells that have been successfully transformed to glow under ultraviolet light.
Hand out the Paper Plasmid student sheets. These contain instruction for the next the student activity portion of this lab.
Almost all new seed varieties being created today have some level of biotechnology involved in their development. From plant tissue culturing to genomic analysis and alteration, all rely on the primary skills of sterile technique and basic understanding of the genetic code. Several different careers in agriculture are fundamental in the development of new varieties of crops: botanists, horticulturalists, biochemists, biological engineers, climatologist, ecologists, food scientists, geneticist, microbiologists, plant pathologist, and an army of lab technicians are all involved in the development of each and every variety.
To learn more about agriculture careers visit https://agexplorer.ffa.org/.
Any educator electing to perform demonstrations is expected to follow NSTA Minimum Safety Practices and Regulations for Demonstrations, Experiments, and Workshops, which are available at https://static.nsta.org/pdfs/MinimumSafetyPracticesAndRegulations.pdf, as well as all school policies and rules and all state and federal laws, regulations, codes and professional standards. Educators are responsible for abiding appropriate legal standards and better professional practices under a duty of care to make laboratories and demonstrations in and out of the classroom as safe as possible. If in doubt, do not perform the demonstrations.
This lesson is the work product of the Kansas Corn Commission. Our lessons are written in collaboration with Kansas teachers for use in the classroom. Teachers may copy and share this curriculum. Use of this product for commercial or promotional use is prohibited without express permission of Kansas Corn.
As the need to produce more food with less resources grows, it is important that future generations have a better understanding of agriculture and how corn farming and agriculture fit into our daily lives. That’s why the Kansas Corn STEM program provides lessons to teach science through the lens of corn. We are committed to providing free materials and training to support educators.
