Seed gene banks exist throughout the world. As you might guess, their purpose is to catalog, store, and protect as many varieties of plants as possible. These banks are useful to plant breeders trying to find crop species that are more drought or disease resistant, for example. They also provide a resource for countries in recovery after natural or man-made catastrophes. For example, after the tsunami in Malaysia in 2004, rice growers were able to obtain salt-tolerant varieties of rice not normally gown in that area. However, many seed banks are located in areas of the world where they are susceptible to destruction. Seed banks in Afghanistan and Iraq have been ransacked.
A consortium of organizations has collaborated in order to address this problem and provide a centralized, stable, reliable site for preserving and protecting world crop seeds. On February 28, 2008, the Svalbard Global Seed Vault began operating. The New York Times and ScienceDaily both reported the event. The Times article, Near Arctic, Seed Vault Is a Fort Knox of Food, is accompanied by numerous photographs and a map indicating the location of the vault. The ScienceDaily article, Thousands of Crop Varieties Depart For Arctic Seed Vault, contains one photograph and numerous links to related articles. Both articles describe the project, who is involved with the project, and why.
Did you know there are about 1,200 varieties of banana plants worldwide? Only about half have been preserved. Other food crops exhibit thousands of varieties as well. The Times notes that, in the United States, “eighty percent of maize types that existed in the 1930s are gone.” The rapid loss of crop plants on the planet heightens the need to preserve as many as possible at this time for their potential in serving future generations.
The Consultative Group on International Agricultural Research (CGIAR) maintains and coordinates seed gene banks around the world, encompassing 600,000 plant varieties. Its goal is to back up all known varieties of useful plant varieties in the Svalbard Global Seed Vault.
How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson
The National Science Education Standards are sometimes criticized for the lack of emphasis on plant biology. However, the Life Science Content Standard for grades 5-8 allows for elaboration on plant biology in many contexts. There are five big ideas within this content standard, none of which excludes plant biology: structure and function in living systems; reproduction and heredity; regulation and behavior; populations and ecosystems; diversity and adaptations of organisms. Teachers should strive to present instruction inclusive of all kinds of living things with respect to these five big ideas, including crop plants.
Entertain student estimates on the number of varieties of bananas, tomatoes, maize, beans, and so on. Present them with statistics reflecting the actual number of known varieties for the crops you choose. Ask what might differentiate one variety from another. Lead students to the idea of differences in optimal growing conditions and variety in tolerance with respect to things like drought, water quality, disease resistance, and yield. Ideally, you may be conducting an ongoing activity in which students grow, observe, and compare food crop varieties for some of these variables.
Can students think of any reasons to try and preserve this variety? Intended for educators, the article Plant Content in the National Science Education Standards lists several reasons for preserving plant biodiversity by virtue of the plant-derived products we depend on to maintain our lifestyle.
Students might recall the tsunami of 2004 or Hurricane Katrina. Ask them if crops that once thrived in those areas could be expected to thrive just as they did before the disasters. Lead them to the idea of salt residue left in soil. Drops of salt water on a paper towel allowed to dry will provide evidence to help students understand soil could be altered by salt water washing over it. Fresh celery or raw potato allowed to sit in salt water demonstrates the effect of salt on plants. Remind students of the Asian rice growers in the ScienceDaily article who found salt-resistant rice in the seed banks.
Imagine your students harvested 300 seeds from plants grown this year at school and you found a way to preserve them. One hundred years from now, students find those seeds and plant them in a natural setting. What do your students predict the outcomes would be? Will the seeds germinate? Will the plants thrive? Will they flower and produce seeds? What rationale do students provide to support their predictions? Lead them to understand the environment will most likely be altered from what it is now. There may be new pests, viruses, pathogens, and competitors. Tie the discussion to natural selection. Is it safe to assume that seeds preserved today can be planted 100 or 200 years from now with great confidence in their success? Then why preserve them? How should they be managed?
Recall the name “gene bank.” These banks can be conceived of as genetic repositories, not simply seed preservation sites. That means there is potential to isolate and manipulate useful genes from preserved seeds. Thus, it may not be necessary that the preserved seeds thrive but that they lend themselves to gene isolation. Periodic germination of preserved seeds followed by collection of new seeds may simulate the natural selection process and increase the probability that preserved seeds will thrive if germinated hundreds of years from now.
What about plants, such as bananas, whose seeds do not preserve well or are not reliable with respect to germination for various reasons. How can those plant species be preserved? There is no pat answer to this question; thus it is an excellent question for student inquiry. Students may propose things like cryogenics of tissues for later vegetative propagation or genomic sequencing for incorporation into some kind of surrogate seed embryo later.
Here are some additional resources from the Middle School Portal 2 related to issues of plant biodiversity and plant breeding: Thinking Green? Grow Your Own! and Seeds of the World: Journey to Forever.
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This post was originally written by Mary LeFever and published March 7, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 3/27/12 by Jessica Fries-Gaither.