Mutant Plants: Teacher Resources
Mutant Plants: Using BrachyBio! to Demonstrate Random Mutation
Synopsis:
This activity is designed to use mutated Brachypodium plants to illustrate the
evolutionary concepts of random mutation, variety, and the adaptive value of new traits. By
directly observing new traits, students can relate how the appearance of random mutations may
be of adaptive value. It should be taught AFTER students already have been exposed to the
topics of Genetics, Gene Expression, and Mutation. Ideally it should be started early on in the
Evolution Unit, to allow time for the plants to grow as students explore the concepts of
Evolution, Classification, and the Diversity of Life.
Target: Regents Living Environment Students
Content Focus:
NYS Living Environment Core Curriculum Standard 4:
Key Idea 2:
- 2a: For thousands of years, new varieties of cultivated plants and domestic animals
have resulted from selective breeding for particular traits.
- 2b: In recent years new varieties of farm plants and animals have been engineered
by manipulating their genetic instructions to produce new characteristics.
Key Idea 3:
- 1b: New inheritable characteristics can result from new combinations of existing
genes or from mutations of genes in reproductive cells.
- 1c: Mutations occur as random chance events. Gene mutations can also be caused
by such agents as radiation and chemicals.
- 1f: Species evolve over time. Evolution is the consequence of the interactions of
(the genetic variability of offspring due to mutation and recombination of genes)
- 1g: Some characteristics give individuals an advantage over others in surviving and
reproducing. The proportion of individuals that have advantageous characteristics
will increase
National STEM (draft):
H.C.2.C: Changes in DNA (mutations) occur spontaneously at low rates. Some of
these changes make no difference to the organism, whereas others can change cells
and organisms. Only mutations in germ cells can create the variation that changes
an organism's offspring.
Time Frame
The activity should take a total of 240 minutes of class time over 7-8 weeks
Stratification (done 48-72 hours prior to lab) –Week 1
30 min-Pre-Lab Activity (in class or as homework)
20 min- Background information, introduction to Brachy and BTI’s goals
60 min- Planting –Week 2
40 min- Screen 1 –Week 3
40 min- Screen 2 –Week 5
40 min- Screen 3, Seed collection & Conclusion–Week 7
40 min- Conclusions & Discussion
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Mutant Plants: Teacher Resources
Teacher Information
Background:
The Living Environment:
Students in Living Environment classes are expected to understand the source of
mutations, the random nature of mutations, the concept of variety as being ultimately caused
by mutations, and the role of mutations in evolution. Examples of observable evolution often
referred to in class include resistance in species exposed to antibiotics or pesticides.
Unfortunately, these are not actually observed by the student, and they often do not convey the
random occurrence of mutations in a natural setting. Students often have a misconception of
the meaning of the word “mutant”, generally believing it connotes something inherently bad or
undesirable.
This laboratory activity is meant to illustrate to students the random nature of
mutations, the production of new traits as a result of those mutations, and the possibility that a
new trait may have some positive attributes. New traits have provided breeders of both plants
and animals with the material they need to cultivate organisms that are in some way beneficial
to humans.
The BrachyBio! Project:
Challenges facing us in the future include feeding an ever growing population, climate
change that may lead to new conditions for traditionally agricultural areas, and a need to
replace petroleum products with cleaner, renewable fuels. As scientists work to meet these
challenges, they often enlist “model organisms”. These organisms’ characteristics make them
ideal study subjects, while their close relationship to commercially valuable organisms make
information gleaned from them easily transferred to larger applications.
Scientists at the Boyce Thompson Institute (BTI) are working with one such model
organism, the grass Brachypodium Distachyon (Brachy). This easy to grow plant’s short
generation time, readily observable characteristics, small mapped genome, and close
relationship to commercially valuable crops such as wheat and rice make it an ideal study tool.
Scientists at BTI have been treating Brachy with Ethyl Methanesulfonate (EMS) to produce
random, single nucleotide mutations. The challenge is now to discover what, if any, new
phenotypic traits are generated by this random mutation process; as well as to determine if any
of these new traits may prove valuable in combating the many problems facing our society.
BTI has initiated an educational outreach program entitled “BrachyBio!” that hopes to
enlist students in the documentation of as many of these new traits as possible. After training,
BTI will furnish your classroom with all the materials necessary to follow a standardized
procedure to grow Brachys from mutated seeds. Students will experience first hand the
discovery of new traits, collaborate with scientists on the forefront of agricultural science, and
participate in solving some of the very serious problems. For details regarding the BrachyBio!
Project through BTI, including video tutorials, visit the BrachyBio! website:
http://bti.cornell.edu/home.php?page=Brachypodium
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Mutant Plants: Teacher Resources
Objectives:
-Students will observe plant development from germination to seed production.
-Students will compare their samples with wild type samples to determine if any observable
mutations have occurred.
-Students will calculate the frequency of mutant appearance in their population.
-Students will assess the adaptive value of the new trait by comparing the number of seeds
produced by the mutated plants when compared to the average of wild type plants.
-Students will theorize the change in frequency of this trait in future populations.
-Students will report back to the scientists at BTI their findings, including photos of any
evidence of mutations.
Resources:
Brachypodium distachyon Wikipedia Page:
http://en.wikipedia.org/wiki/Brachypodium_distachyon
Food Shortages And Global Economic Riots In 2011: YouTube Video:
http://www.youtube.com/watch?v=Ss8fkiDu5lo
Susan McCouch talks about research on the wild ancestors of cultivated rice: YouTube Video:
http://www.youtube.com/watch?v=L2yJLKQ4R3U
Los Angeles Times Article: “A ‘time bomb’ for world wheat crop:
http://articles.latimes.com/print/2009/jun/14/science/sci-wheat-rust14
British Society of Plant Breeders booklet:
Plant Breeding: The business and science of Crop Improvement:
http://www.bspb.co.uk/BSPB%20Handbook.pdf
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Mutant Plants: Teacher Resources
Teacher Lab Procedure
Materials:
Student handout
Grow trays with 54 wells total
Soil: Miracle Grow Potting Mix with Micromax
Petri dishes
Sharpie pens
Parafilm
Tweezers
Water
Camera to photograph mutants
Rulers
Light rack*
Plant tags*
Seed packets*
Thermometer/Light meter/Humidity meter*
*Will be supplied by BTI as part of the BrachyBio! Kit to maintain consistency among groups
Safety:
-
Any students with potential allergies to grass should notify the teacher and should
avoid contact with the plants.
All students should wash their hands before and after handling the plants or seeds.
Any injuries while working with the laboratory materials should be reported to the
teacher immediately.
Students should not manipulate the light set-up while experiment is in progress.
Pre Lab Teacher Preparation:
Stratification: Simulating Winter
-Thoroughly wash or sanitize your hands before and after working with seeds.
-Place each family of seeds (12) in a sterile petri dish.
-Add 20 ml of water to each dish, and seal the edges with parafilm.
-Label each dish with the seed family number
-Place all dishes in the refrigerator for 48-72 hours
Each student is to be given one petri dish (family) of seeds to work with…this should minimize
confusion and help maintain consistency in reporting.
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Mutant Plants: Teacher Resources
Pre-Laboratory Activity (30 minutes)
Assigned either in class or as homework, the Pre-Lab activity will introduce students to
ideas such as the need to increase crop yield, the growing global population, and model
organisms.
Introduction: Motivating the Students (20 minutes)
-Use the Power Point presentation “Brachy Intro” provided, or create your own
-Expose students to some of the issues plant scientists are dealing with through current
event articles or online videos.
(again, some of these are provided)
Lab Day 1: Planting the Seeds. (60 minutes)
You will receive from BTI several packets of seeds with each packet containing 12 seeds. This
represents one family. The soil (Miracle Grow Potting Mix) you will be using must be purchased
from a local home or garden center. A 16 quart bag should be enough to plant 3 full trays. Soil
should be moist prior to planting. Each tray liner has 3 soil filled containers. The 12 seeds you
receive in each packet will be planted in these 3 areas with 4 seeds per container.
-You should plant one family of “wild type” Brachyo to serve as a reference.
-Be sure to place the correct tag with the family number / date and teacher written on it
into the soil liner as shown. The integrity of this experiment depends on getting the correct
family number associated with the correct seeds.
-Seeds are pushed using a forceps gently just below the surface. Leaving a little of the awn
(the long thread like stalk on top of the seed) exposed helps you see where you have
planted them. Water the seeds thoroughly by adding water to the open area in the tray.
-Add water to just cover the BOTTOM of the tray (~ 200 – 300 ml of water). Keep adding
water as needed to keep the soil moist. DO NOT OVER-WATER! Make sure you account for
weekends and holidays when you are develop your watering schedule. Brachypodium plants
are tough and like most weeds require very little except sufficient water to grow.
Lab Day 2: Screen 1, at about 1 week (40 minutes)
By now, the seeds have germinated. Students should be able to determine not only which
plants are growing, but they may see minute differences in a few of them. Always have Wild
Type plants on hand for student reference, as well as a computer in the room open to the BTI
BrachyBio! Website:
http://bti.cornell.edu/home.php?page=Brachypodium .
-Encourage students to make as detailed observations as possible.
-Be sure to record the environmental conditions in the classroom.
Lab Day 3: Screen 2, at about 3 weeks (40 minutes)
Plants are now mature and branching of control plants has occurred. Students should pay
careful attention to those plants that appeared to be different during Screen 1. They should
also be looking for new traits, that may not manifest themselves until further along in the plants
development. In addition to wild type plants and the website, have hand lenses available.
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Mutant Plants: Teacher Resources
Lab Day 4: Screen 3, about 6 weeks after planting (40 minutes)
By now, wild type plants should have produced seeds. You must carefully remove the seeds
from EACH WILD TYPE PLANT, and count how many seeds it produced. Find the average
number of seeds produced by Brachy wild type plants in your classroom environment. This will
serve as a reference for the reproductive success of any mutations that may have appeared in
your class.
-Students should make their final observations (again, in as much detail as possible).
-Take digital photos to be sent to BTI for inclusion in their “Mutant Library”:
-Any Mutant, ruler, and Tag with Family Number in photo
-One Wild Type grown under your conditions, ruler in photo
-Have students remove and count seeds from each plant.
-If no mutant appears in a student’s family, they should find the average of their wild
type plants to create a more reliable average seed count for wild type in this
environment.
Compiling Class Data:
On display in the classroom (either projected onto a Smartboard or on a computer) have
open the “Teacher Data Summary Sheet” Excel file available at:
http://bti.cornell.edu/home.php?page=Brachypodium&section=TeacherResources
If mutants have been identified in a student’s family, they should enter all the appropriate
data into this file. Use a digital camera to photograph each mutant (include the tag with the
Family # and a ruler for scale), and upload an image for each mutant.
Conclusion & Discussion:
After students have completed the activity, host a class discussion where students share
their results. Any unique traits that appeared should be displayed, and a discussion should
ensue as to its adaptive value. Questions should be raised regarding the new trait’s qualities,
and its value either in nature or as a commercially viable quality.
Any unique traits must be reported back to BTI. You may choose to compile the
information and send away the data along with the mutant plants’ seeds. Depending on your
circumstances, you may want to compile the data and enter it yourself; or you may want the
students to enter their results individually. The BTI website contains the EXCEL spreadsheet
for entering a class set of data
*PROCEDURE PENDING FOR REPORTING DATA TO A BTI DATA BASE*
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Mutant Plants: Teacher Resources
Optional Extensions
The following activities are only some of the many extensions the BrachyBio! Project
may be used for a starting point. Inquiry based experiments ranging in topics from abiotic
effects on plants, genetics, nutritional analysis, selective breeding, and population genetics can
all be derived from the information and protocols students master as a result of BrachyBio!.
Reporting:
Students can develop speaking skills, process and communicate ideas, and receive
feedback from peers by preparing a presentation regarding their findings. Reports can be
presented to the class, posters can be generated, and a class summary of findings can be
produced by compiling student’s slides. An ‘in house’ library of Brachy mutants can be added to
with each additional class’ data.
Heredity & Evolution:
By saving the seeds produced from known mutant plants (either new varieties observed
directly by the student or those provided in the Mutant Garden), students can grow subsequent
generation and track the frequency of the known mutation’s appearance. Students may then
determine if the new gene is dominant or recessive; modeling the work done by Gregor Mendel.
The same approach that may lead students to study the subsequent generations of
Brachy mutants can be applied as a model for selective breeding. Students may select for a
particularly desirable trait, and design a protocol for developing a reliable line of that mutation.
Students can develop a research plan to test the viability of one of the mutant varieties
under specific growing conditions. Hypotheses can be made as to the conditions a particular
trait might grow well under (less water, less light, different soil etc.). An experiment can then
be designed using the wild type seeds as a control.
This by no means exhausts the list of possible extensions BrachyBio! may provide.
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Mutant Plants: Teacher Resources
Vocabulary
Mutation: A change in DNA base pairs
Mutagenic Agent: Any substance that can change DNA, including UV radiation, asbestos, and certain
chemicals.
Variation: The amount of diversity within a species or population.
Model Organism: An organism chosen by scientists for study, usually based on characteristics such as
short generation time, high reproductive rates, easily observed characteristics, and close relative
relationship to other organisms.
Genotype: The two specific alleles an individual has for a trait.
Phenotype: The physical appearance of a genes of an individual.
Silent Mutation: A change in DNA that does not produce a change in the phenotype.
Wild Type: Considered the typical phenotype for the species, considered “normal” when compared to
new, possibly mutant traits.
Adaptive Value: The ability of a new trait to add to an individual or species’ chances of survival.
Gene Frequency: How often a gene appears within a population.
Variegated: Plants with a variety of colors on the same leaf.
Virescent: Not fully green as compared to the wild type.
Albino: No color: white
Necrosis: Death of tissue.
Plant Architecture: Structures of the plant, leaves, stems roots, and the patterns they take.
Spikelet: A flowering structure common to grasses, where a reduced flower is encased in several
protective structures.
Serrated: Having notched or jagged edges.
Selective Breeding: The process where humans control the reproduction of a species to favor certain
desirable traits.
Genetic Engineering: Technology where DNA from one organism is placed into a different organism.
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Mutant Plants: Teacher Resources
Vocabulary
Mutation:
Mutagenic Agent:
Variation:
Model Organism:
Genotype:
Phenotype:
Silent Mutation:
Wild Type:
Adaptive Value:
Gene Frequency:
Variegated:
Virescent:
Albino:
Necrosis:
Plant Architecture:
Spikelet:
Serrated:
Selective Breeding:
Genetic Engineering:
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