The purpose of this activity is to demonstrate the effect of changes in the environment on the growth and fertility of landscape grasses and crop grasses such as wheat and rice. You will place the plants in environments such as high salinity, cold, heat, or drought and observe the different reactions of the plants to these conditions. Students will compare the growth of treated plants to that of the control plants which are grown under optimal conditions. You will then discuss the desirability of breeding new types of plants that are better able to withstand these changes if they occur in the general environment.
Breeding plants that are able to survive in different environmental conditions or when attacked by diseases or pests has occurred for thousands of years as people gradually domesticated the plants that they needed to use for food or as ornamentals. Generally this breeding involved identifying a trait in another related species that could then be used as the donor of this trait to the domestic plant they wished to improve. In traditional plant breeding, the two species would be crossed either naturally or artificially to produce a hybrid plant that contained genes from both parents. These hybrids were screened to see which of them contained the gene for the trait of interest. The selected hybrids were backcrossed to the domestic parent over many generations with selection at each step for the trait of interest. This ultimately results in a new plant that contains DNA mainly from the original domestic parent but also a small amount of DNA from the donor that encompasses the gene that we desired to transfer. As you can imagine this procedure is very expensive and time consuming and it is many years before a new plant is ready to be released to the general population. A second drawback with this procedure is that there is inevitably some DNA present in the new plant that arose from the donor parent that may not be desirable.
A second method of breeding involves the use of biotechnology. Some of the laboratory techniques that you have learned in this program in the activities DNA extraction, restriction digestion, plant tissue culture, transformation and PCR are utilized in this type of breeding. The gene for the trait that we are interested in may be identified in either a related species or even a totally different genus or family. For instance a gene from a fish that is able to survive in very cold conditions has been bred into soybean so that the plants are now able to survive in much colder environments than the original soybean. The specific DNA that contains just the gene of interest can be cut out of the donor organism's DNA, cloned and prepared for insertion into the recipient plant. Transformation procedures are utilized to move the gene into the recipient and new plants are grown in tissue culture before moving into the greenhouse and the field. Selection methods are used during tissue culture to select only plants that have the new gene in their cells and thus these are the only ones that continue through the whole procedure. Once plants are mature enough to be planted in the field or greenhouse some of the more traditional methods of plant breeding are used to increase the number of plants, to test that the gene functions correctly under the relevant conditions, to determine if the new gene is stably inherited and, most importantly, to check that the new plants do not have a detrimental effect on either the environment or other plants and organisms.
Note: The seeds must be germinated and planted at least 5 weeks before beginning the experiment. If you only want your students to see the results of the treatments, then you should begin at least 7 weeks before the class period is to occur.
Treat as follows:
+You can have the class work out how to make this solution as part of a chemistry or mathematics lesson. A 1Molar solution contains 1 mole of the solute dissolved into 1 liter of water. 1 mole of NaCl contains 58.44 grams i.e. number of grams equivalent to the formula weight of NaCl. So, to make 100 mM we need to take 58.44/10 grams of NaCl. (100mM = 1M/10 or 1000mM/10). So you need to dissolve 5.844 grams of NaCl in water and then make the volume up to 1 liter for each liter of saline solution that your container will hold.
Examples of expected results:
Some other questions to have students consider:
What do you think are important tools for improving our ability to feed the world?
Are there technologies that you think should not be used?
Find out how you could become a scientist who has the power to change children’s lives by providing growers with the tools to grow nutritious food necessary for the healthy development of our children.
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